Saurabh's blog

R -> output to CSV -> Latex -> pdf (CSV -> Latex -> pdf)

2011-12-11T19:19:00.000-08:00

Update: My friend pointed out that there are in fact several ways of including the output of R into a tex file. However what I'm using now is the package csvtool.

I would like to carry out data analysis in R and generate pdf files using Latex which include the results of the analysis.

The issue: For graphics, one option is to save the figures as eps files in R (for e.g. by using postscript() command) and to include them in the final pdf file through Latex. What about other numerical results ? One option is to calculate the output (for e.g. the values of some variables) then copy those values from R into the Latex file. How ever I do not want to copy-paste them. I would like to run some R script, generate some results, and then run Latex which will pick up those results and create the pdf file.

A solution: In R export the results as a csv file (for e.g. using the write.csv() command). I find it best to first put the results in a tabular form and then write it to the csv file. Then using Latex include this csv file in the final pdf output as a table with the command \DTLdisplaydb{file_name}, which is available in the datatool package(\usepackage{datatool}). If the table is large and runs out of the page (in the portrait page setting), you can consider rotating the table by 90 degrees with the \begin{sidewaystable} ... \end{sidewaystable} command available in the rotating package.

So basically something of this sort in Latex:
.
\usepackage{datatool}
\usepackage{rotating}
.
\DTLloaddb[noheader,keys={},headers={}]{}{} % Look up the documentation for command options
.
\begin{sidewaystable}[] % Look up the documentation for command options
\centering \caption{}
\DTLdisplaydb{file_name} % Look up the documentation for command options
\end{sidewaystable}
.

Note: There are macros available for MS-Excel using which you can select a table in Excel and generate the corresponding Latex commands. However for that you will have to open the csv file first in MS-Excel.

Hiking: Cascades (VA)

2011-10-15T19:09:00.000-07:00

Cascades is one place we have hiked in Summer, Winter and (now) Fall. The Fall colors seemed to be all around us and we decided to go to Cascades to make the most of the sunny (though not so warm) Saturday afternoon. The hike starts from a parking lot which is about 20 miles from Virginia Tech. The drive is nice and quick.

At the parking lot you have to pay $3.00. On a nice day the lot can be full, in which case you would park on the road side.

There is a board which will explain to you that there are two different routes you can take to the cascades. Though initially and finally they both merge. It is easier and more fun to cross the first bridge and go to the right and come the other way.

All along the trail is nice, though unlike the typical AT-trail there are no markings here.

For most part you will be walking next to the water (assuming that you crossed the first bridge).

Now with the Fall colors the trail looked even more beautiful.

I did take pictures along the way but I'm not in a mood to upload all of them to explain landmarks etc. Also, the cascades are shown in the picture at the beginning of this post. This time we also went over to a new trail which leads to the upper-falls.

Hiking - distances from Drillfield Dr to parking

2011-10-09T10:00:00.000-07:00

Approximate driving distances from War Memorial Chapel (Drillfield) Virginia Tech. to the trail parking:

Sharp Top..........................69.4 miles (1 hr 18 min)
Rock Castle Gorge................38.4 miles (1 hour)
Tinkers Cliff.......................30.3 miles (51 mins)
McAfee's Knob.....................23.1 miles (41 mins)
Angels Rest........................25 miles (35 mins)
Dragons Tooth.....................21.4 miles (39 mins)
Kelly's Knob........................16.1 miles (26 mins)

Hiking: Tinkers Cliff (VA)

2011-10-09T07:53:00.000-07:00

This weekend we went to Tinkers Cliff. The trail starts from a parking lot off Catawba Rd. (VA-799), close to the intersection of Little Catawba Creek Rd. and Catawba Rd.

Time stamps:
Photo which shows the yellow mark on the tree (almost at the start of the hike): 11:16am
Photo with the no trespassing sign: 12:10pm
Photo with wooden signs on the tree: 1:08pm
Photo showing the rocks at the top: 1:35pm

From the parking lot the trail is marked with the yellow signs on the trees.

At the beginning of the trail there are two wooden bridges and a small stretch next to a stream.

For most part the trail is shaded with lots of trees.

You will arrive at a No Trespassing sign. Right next to the sign, on a tree, there is a posted sign which points in the direction of the trail. This basically tells you to ignore the sign and go ahead in the direction which otherwise you would think the sign is warning you not to go. Just remember, follow the yellow signs.

After some nice upward climbs you will see wooden signs on a tree pointing you in the direction of Tinkers cliff. After this point you have to follow the white marks on the tree (for the AT).

From this point the Tinkers Cliff overlook is 0.5 miles. At the overlook there are numerous rocks from which you can select the one most comfortable for yourself and, sit, relax and enjoy the view.

Exposure: Part 1, Shutter speed, aperture and ISO value ~ Brightness

2011-07-30T19:56:00.000-07:00

Controlling Exposure

In case you just need the key points, they are:

You need a brighter image: use a bigger aperture i.e. smaller F-number, longer exposure time, and higher ISO.
Larger the aperture opening brighter the image.
Larger the exposure time brighter the image.
Higher the ISO value brighter the image and more the noise.
The aperture also determines the depth-of-field i.e. over what distance do the things appear to be in-focus. This can be used to blur-out the background for e.g. as in this picture. You can read more about this here.
You need to keep your hand stable for the duration of the exposure time else the final picture will be blurry. This blur caused due to camera shake can be used creatively for e.g. as in this picture. Use a tripod. Longer exposure time can be used to create silky water effect, get lovely night pictures etc.
At high ISO noise can be an issue.

Now the illustrated story

When you press the button to take a picture light falls on the sensors and it is recorded. The brightness (I will also call it the exposure) of the final image is therefore dependent on three things:

How big is the opening through which light is coming in i.e. aperture value
For how long does light fall on the sensors i.e. shutter speed or exposure time
How sensitive are the sensors to light i.e. ISO value

The aperture size also determines the distance over which everything looks sharp and in-focus. This is typically called the depth-of-field. I won't address that part here. You can read about it in one of the previous posts.

Below I will show you some pictures which will hopefully explain to you the use of the three values (aperture, shutter, ISO) in determining the final exposure or brightness of an image. Lets deal with them one at a time.

How big is the opening through which light is coming in: Aperture

The aperture is the opening through which light passes and then reaches the sensors. Obviously larger the aperture more light comes in, and smaller the aperture less light comes in. You can think of it like a window in your room. If the window is bigger more light can come in. The aperture value is typically mentioned as the F-number. What you need to remember is this:

Smaller the F-number <==> Larger is the aperture opening <==> More light comes in
Larger the F-number <==> Smaller is the aperture opening <==> Less light comes in

Also as I mentioned above, aperture also determines the depth-of-field.

Consider the six pictures shown below in Figure 1. All the six pictures were taken with a Nikon D40 mounted on a tripod. For all the six, the shutter speed or exposure time was 1/10 sec. and the ISO value was 200. However a different aperture value was used for each of them. This makes it easier to see the effect of aperture on the final exposure. The aperture values that were used are mentioned in the bottom right corner of each individual picture.

Figure 1: The effect of aperture on brightness. The aperture values for individual pictures are mentioned in the bottom right corner. The same shutter speed (1/10 sec.) and ISO value (200) were used in all the six cases.

What you will notice from the six pictures shown in Figure 1 is that as the F-number increases from 4 to 25 the pictures become darker. That is because as the F-number increases, the aperture opening becomes smaller and thus less light makes it to the sensors for the same exposure time.

How long does light fall on the sensors: shutter speed or exposure time

The light will pass through the aperture and be collected by the sensors for the duration commonly called the shutter speed or the exposure time. This is mentioned in seconds. What you need to remember is:

Shutter speed or exposure time of for e.g. say 1/10 seconds means that light will be captured for 1/10 seconds.
So with a shutter speed of 1/10 seconds you will capture more light than with 1/100 seconds.
Also, say for e.g. you use a shutter speed of 1/10 second. Then light will be captured for 1/10 second and the camera needs to be stable for that 1/10 second else the final picture will be blurred. This blur caused due to camera shake during the exposure time is typically undesirable but can also be used creatively for e.g. in this picture.

Anyway. Consider the six pictures shown below in Figure 2. All the six pictures were taken with a Nikon D40 mounted on a tripod. For all the six, the aperture value was F/5.6 and the ISO value was 200. However a different shutter speed was used for each of them. This makes it easier to see the effect of shutter speed on the final exposure. The shutter speeds that were used are mentioned in the bottom right corner of each individual picture.

Figure 2: The effect of shutter speed on brightness. The shutter speed for individual pictures are mentioned in the bottom right corner. The same aperture (F/5.6) and ISO value (200) were used in all the six cases.

What you will notice from the six pictures shown in Figure 2 is that as the shutter speed goes from 1/4 sec. to 1/250 sec. the pictures become darker. That is because as the exposure time, or the time for which light falls on the sensors, decreases the picture becomes less and less bright for the same sized aperture.

How sensitive are the sensors: ISO value

The light comes in through an opening, the size of which is the aperture value, and falls on the sensors, for duration equal to the shutter speed or exposure time value, and then falls on the sensors. So by altering the sensitivity of the sensors you can control the final brightness. The sensitivity of the sensors is mentioned in terms of the ISO value. What you need to remember is this:

Lower the ISO value <<==>> Lower is the sensitivity of the sensors <<==>> Less is the noise in the final image
Higher the ISO value <<==>> Higher is the sensitivity of the sensors <<==>> More is the noise in the final image

I will come to "noise" in a minute. First consider the four pictures shown in Figure 3. All the four pictures were taken with a Nikon D40 mounted on a tripod. For all the four, the aperture value was F/5.6 and the shutter speed was 1/8 sec. However a different ISO value was used for each of them. This makes it easier to see the effect of ISO value on the final exposure. The ISO values that were used are mentioned in the bottom right corner of each individual picture.

Figure 3: The effect of ISO value on brightness. The ISO values for individual pictures are mentioned in the bottom right corner. The same aperture (F/5.6) and shutter speed (1/8 sec) were used in all the six cases.

What you will notice by comparing the four pictures is that the one with ISO 200 is darker than the one with ISO 1600. This is because at 1600, the sensors are more sensitive and thus the picture is brighter even though the same shutter speed and aperture value were used. Actually, the sensors don't get magically more sensitive, but lets just leave that issue.

Typically you would want to use the least ISO value possible but at that value the noise is least. However for e.g. if shooting in the low-light conditions you might want to increase the ISO. Now something about noise.

Consider the four pictures shown in Figure 4 below. Only the ISO values (as mentioned in the bottom right corners) were changed and the shutter speed (1/50 sec) and aperture (F/5.6) were the same for all the four pictures.

Figure 4: The effect of ISO value on noise. Shutter speed: 1/50, F/5.6

Well, this is not a very good example but you should be able to see the "grainy" noise in the picture with ISO 1600. This picture is shown separately below in Figure 5.

Figure 5. ISO: 1600, hope that you can see the noise

Happy shooting.

In summary

You need a brighter image: use a bigger aperture i.e. smaller F-number, longer exposure time, and higher ISO.
Larger the aperture opening brighter the image.
Larger the exposure time brighter the image.
Higher the ISO value brighter the image and more the noise.
The aperture also determines the depth-of-field i.e. over what distance do the things appear to be in-focus. This can be used to blur-out the background for e.g. as in this picture. You can read more about this here.
You need to keep your hand stable for the duration of the exposure time else the final picture will be blurry. This blur caused due to camera shake can be used creatively for e.g. as in this picture. Use a tripod. Longer exposure time can be used to create silky water effect, get lovely night pictures etc.
At high ISO noise can be an issue.

War Spur Overlook (VA)

2011-06-28T20:05:00.000-07:00

If you have been to the Wind Rock overlook then most likely you would know about the War Spur (WS) overlook. The WS overlook is about 3 miles from the Mountain Lake resort. The road side parking spot is off SR-613. I will not explain the exact location but in short its: US460 --> Mountain Lake Rd. --> SR 613. The last about 1.5 miles or maybe 2 miles of the driving stretch is gravel and with lots of pot holes.

The WS overlook is a peaceful spot with lots of rocks to sit and look at the mountains. However, unlike the Wind Rock overlook I don't think you can see the lovely sunset colors from here. The mountains in front of you would block the view.

The hike for the WS overlook starts from the off-the road parking spot on SR-613. At this point you have the wooden sign indicating the loop. The hike is small, about 3 miles for the complete loop.

Its a loop so you can go either from the left side (clockwise)

or the right side (anti-clockwise). I started from the right.

The hike is through the forest area and is well shaded with lots of greenery.

There is a small stream which you will cross.

Soon you will arrive at a wooden post which will point you in the direction of the overlook.

After a small mainly down-slope stretch (so it will be up-slope while returning) you will come to the clearing of the overlook.

The overlook has lots of stones where you can sit and enjoy the scenery.

Do remember that a portion of the drive is not so good. Also, in case you haven't been there, then also visit the Wind Rock overlook.

Wind Rock overlook (VA)

2011-05-30T08:53:00.000-07:00

This is simple. You drive. You park. Walk for less than 10 minutes. You get the best view. Even great is the fact that you will be facing west (of-course you can decide to face the other way) so the view is simply great if you wait till after sunset. The pictures in the post are from two different trips to Wind Rock and thus the difference in greenery.

Where is it ?

Heard of Mountain Lake Resort in Virginia ? Heard of the movie "Dirty Dancing" ? One of the reasons why the Mountain Lake Resort is popular is that it was the location where the movie "Dirty Dancing" was shot. About 5 miles from the Mountain Lake Resort is the Appalachian Trail. That's where the Wind Rock overlook is.

Where exactly on the map ?

You can find information about it on the internet. In Google-maps search for "37.412001,-80.522675". This location is on State Route 613 or the Mountain Lake Road. Here is the link:
http://local.google.com/maps?q=37.412001,-80.522675&num=1&sll=37.0625,-95.677068&sspn=23.875,57.630033&ie=UTF8&ll=37.412105,-80.522691&spn=0.001672,0.001548&z=19

If you zoom-in and look in the "Satellite view", you will notice a clearing just off 613. That is the parking place. Depending on how you are looking at it, if the parking is on the left, then on the right is the trail where you need to go. There is a wooden board on the right and the trail is pretty obvious. Also, it has white marks on the trees. So park here and then walk.

What is the best way to get there ?

From the Virginia Tech campus there are two ways you can reach the Wind Rock parking lot. Obviously I'm assuming that you will drive and that you need a straightforward route.

One way is: US460 --> Mountain Lake Rd (613) --> Wind Rock
Another option is: US460 --> Big Stoney Creek Rd (635) (this is after you cross the road to Cascades) --> State Route 613 --> Wind Rock

This route is longer. However it is much more scenic. The pictures (with water) featuring in the post "Motion blur, silky water effect" (http://bishtss.blogspot.com/2011/05/motion-blur-silky-water-effect.html) were taken on this route.

On both these routes look out for deer's. (The picture below was taken by a friend. I tried taking pictures of deer's but they just did not like the idea)

How is the drive ?

The final stretch, my guess is the last 2 to 3 miles, on both these routes is "bad". I would say it is less bad when taking the first route. The drive is bad but not that bad really. But in case you or your car or others in the car really don't feel comfortable then there is an option of park-and-walk. When you are taking the first route, an option is to park about 2 miles from Wind Rock (about 3 miles after the Mountain Lake resort) in a parking area from where another loop trail starts. In this case you will have to walk about 2 miles (uphill) to reach the Wind Rock parking spot. I think this is the place where you can park (don't come after me if it is not) :

http://maps.google.com/maps?f=d&source=s_d&saddr=Mountain+Lake+Rd%2FState+Route+613&daddr=Mountain+Lake+Rd%2FState+Route+613&hl=en&geocode=FXyJOgIdo4oz-w%3BFaDcOgIdUlIz-w&mra=ltm&dirflg=w&sll=37.402142,-80.517254&sspn=0.053797,0.049524&ie=UTF8&ll=37.401426,-80.514464&spn=0.026762,0.024762&z=15

Anything else ?

If you make the effort to reach Wind Rock then stay there till after sunset to see some amazing views. Visit it in different weather conditions. Obviously take your safety into consideration. You can also camp there for the night.

Motion blur, silky water effect

2011-05-27T18:36:00.000-07:00

If you want to be creative with your camera then one way is to start by understanding the use of shutter speed (exposure time), aperture and ISO.

You can read about aperture in one of my previous posts:
http://bishtss.blogspot.com/2010/11/f-number-minimum-you-would-like-to-know.html

I won't talk about ISO here. All the pictures featuring in this post were taken with the ISO set to its minimum value (80 on the Panasonic ZS7, and 200 on the Nikon D40).

I have been asked several times about (a) how to take pictures of water with the silky effect and (b) how I took several "light painting" pictures (for e.g. https://picasaweb.google.com/saurabh.bisht/Year201X#5578543189702625810).
The most straight forward answer to both these questions is: I increased the shutter speed == I used a slower shutter speed == I increased the exposure time.

Shutter speed == exposure time == the duration of time for which the camera captures whatever it sees.

For e.g.: Shutter speed of 1/10 sec == faster shutter speed == less exposure time in comparison to a shutter speed of 1 sec.
For e.g.: Shutter speed of 1/10 sec == slower shutter speed == more exposure time in comparison to a shutter speed of 1/100 sec.

To get the silky effect in water you want the camera exposure time to be long enough so that during the time which the camera is capturing the image, the water moves thus creating a motion blur. There is no universal shutter speed value to use, you will have to see what value works best for the scene and for your purpose.

You can set the shutter speed (or the exposure time) in either the "shutter" mode or the "manual" mode of the camera. If you are just setting the shutter speed then one issue you might run into is that the final image might be too bright. In such situations, one option is to control the final brightness by changing the aperture value. Now since you want to set both the shutter and aperture value, you need to work in the manual mode. Another option is to take the picture when its not too brightly lit, for e.g. avoid bright sunny conditions.

Consider the pictures shown below. These were taken using a Panasonic ZS7 mounted on a tripod. I used the shutter mode. I selected the shutter speed; the camera selected the aperture value. The ISO was set to 80. Compare the ones on the left with those on the right. The shutter speeds which were used are mentioned in the pictures.

Figure 1. Pictures taken using a Panasonic ZS7 mounted on a tripod. Mode: Shutter, ISO: 80.

Don't compare the overall brightness. Compare just the water and how it looks. The pictures on the left had a faster shutter speed in comparison to their counterparts on the right. In the pictures on the left, the water seems to have been frozen in motion. In comparison there is a motion-blur in the pictures on the right. Due to this difference you can see the silky effect more in the pictures on the right.

Another example. Consider the pictures below. These were taken using a Nikon D40 mounted on a tripod. I used the manual mode. That way I selected the shutter speed and aperture. This gave me more control on the overall final brightness of the picture (I was not concerned about the depth-of-field effect of aperture). The ISO was 200. The shutter speeds and aperture values which I used are mentioned in the pictures.

Figure 2. Pictures taken using a Nikon D40 mounted on a tripod. Mode: Manual. ISO: 200.

Again note that with a slower shutter speed, the picture on the right, the silky effect is more prominent. In comparison, with a faster shutter speed, the water seems to have been frozen in motion.

Hopefully this explains how to take pictures with silky water effect and some basics about the use of shutter speed. The picture shown below was taken using a Panasonic ZS7 in the shutter mode, with a shutter speed of 1 sec. Happy Shooting.

Hiking: Angels Rest (VA)

2011-05-08T13:51:00.000-07:00

For hiking we had already been to Cascades, Dragon's tooth, McAfee's knob, Tinkers cliff and Kelly's knob. All were fun and with varying difficulty levels. So last weekend we thought of going to Angels Rest. Why ? First, we wanted to. That's a good enough reason. Second, because we had not been there. Third, it seemed to be "the hike". We wanted something which would be the toughest hike we had done recently. Checking on the internet it seemed that Angles Rest would be it. Reading about it we got the impression that it was a (about) 2.5 mile hike. The last 1.5 miles being really tough. Plus the vertical profile was pretty much a straight line with a nice positive slope. So there we had it.

Considering that it was going to be "the" hike we took special care that we had lots of water and enough food. The hike was fun. Just that it did not meet my expectations.

In short:

(1) From the starting point to the Angles Rest view rock its a 1.7 mile hike.
(2) This 1.7 mile portion is indeed a good hike. Just that we were expecting that it would be a total of 2.5+ miles.
(3) I think the view from the Angles Rest is ok, not great.
(4) If you go further, about 0.6 miles beyond the Angles Rest view rock, you will get a very good view of the Wilburn valley.
(5) Considering that its just a 1.7 miles portion which is tough, the overall hike is not as tough as I had imagined.

Time stamps:
First photo showing the AT sign: 9:12am
Photo showing the wooden sign for the view rock: 10:22am
Photo showing the view of the Wilburn valley: 11:14am

We started from the intersection of State Route 793 and the Appalachian Trail (AT). (US 460 --> VA 100 --> Johnston Ave --> Morris Ave). There is limited road side parking available. Also note that probably you can start from some location further down on the AT and then maybe its a 2.5+ miles hike. However this is the starting point mentioned on most of the websites.

The trail is shaded with lots of trees. Also since it was spring we had lots of greenery.

Its all an uphill climb for 1.7 miles. That is when you will come to the following sign which will point you towards the Angels Rest rock.

From the rock, among other landmarks, you can see the new river.

After you have rested and seen the view, you can go back to the wooden sign and proceed in the direction of "Wilburn Valley View". On the way you will cross a sign which says "Spring".

You can continue and pretty soon you will reach a portion on the left which has some rocks on which you can sit and enjoy a very good view of the valley.

U.S. Cycling Route 76 (VA)

2011-04-29T15:07:00.000-07:00

While cycling I had seen this sign on the road many times. That's the sign for the Cycling Route 76. You can get more information about it on the internet. I mapped the portion of Route 76 which passes through VA. Do remember to check the routes before you go cycling.

The Virginia portion mapped at Bikemap.net:

http://www.bikemap.net/route/930973

Bike route 930973 - powered by Bikemap

From where did I get the route info:
http://www.opencyclemap.org/

Hiking: Dragon's Tooth (VA)

2011-04-25T13:06:00.000-07:00

The temperatures were favorable and the weekend had to be utilized for outdoor activities.
Saturday: Biking. Sunday: Hiking.

For hiking we decided to revisit the Dragon's Tooth.

For some of the pictures I have mentioned the time (as given by the camera). This might give you an idea of how long it would take to complete the trail.

Picture taken at the starting point: 11:38am
Picture taken at the top (shown above, one in which you can see the tooth): 1:11pm
Picture of the wooden bridge, taken while returning and close to the starting point: 2:57pm

The Dragon's Tooth is a 4.6 miles long hike which starts off VA-311.

The trail is well marked.

At the beginning you will cross a couple of wooden bridges and small streams of water.

The trail is clean and nice with lots of trees.

You will come across a camping area (at-least a flat small clearing area) where the wodden signs will point you towards the trail.

After this, the path will become rocky. Just follow the marking.

A couple of times you will go rock climbing.

Soon after climbing the rocks shown in the above picture, you will get the first clear view of the valley.

Just keep on going. At the very top the wooden sign will again point you towards the tooth.

Do climb the tooth. The view from the top is nice. This time I forgot to make a video. But the pictures serve the purpose.

Hiking: Kelly's Knob (VA)

2011-03-19T21:29:00.000-07:00

Kelly's Knob is a total 6.6 miles hike. I did not measure the distance but that is what is mentioned somewhere on the internet and after the hike it seemed reasonable. It took us a total of about 6 hours for the round trip, from the time we parked and started on the trail till the time we were back to the starting point. Along the trail we made several stops, relaxed, took pictures, and spent a lot of time on the rocks at Kelly's Knob.

The starting point (one of them) is off Route-42. You will see the sigh saying "Appalachian" on the right (when coming from US-460 E --> Route 42), just before State Route 629 (on the right). That is where you can park.

After parking, cross the road and the trail starts. The trail is well marked and you just need to follow the white marks on the trees. In case it has rained, then parts of the trail can be messy, specially at the very beginning. Some views at the very start:

Before you enter the forest, you will cross a couple of wired fences using wooden ladders. The scenery before the entry into the forest is pretty nice.

Pretty soon the clear scenery part will end and you will cross a wired fence into the woods.

Along the trail you will pass a shelter (at about 2 miles) and soon after that you will come across Laurel Creek. You will cross the creek twice.

After you cross the creek the hike is pretty steep for the next about 0.9 miles. Once you have ascended this part, the trail will become pretty flat (relatively speaking). From there (as you have been doing till now) just keep following the white marks on the trees. Along with the white mark, look out for a blue one. The first blue mark will come on the left, on a tree which has a wooden sign board pointing towards the direction of the "view". From this point just follow the blue marks on the trees.

The "view" is a clear (flat) rocky area. You will have to jump and be a little bit adventurous to actually go on the rocks to see the view.

View from the top (video):
http://www.youtube.com/watch?v=Ulw4ZuKjowc

Focal length

2011-03-11T15:16:00.000-08:00

What is the deal with the focal length ? What is the difference between 18-55mm and 55-200mm lens ? What is zoom ? Is the focal length of my point-and-shoot camera and DSLR directly comparable ?

Short story:

So DSLR or point-and-shoot camera

smaller focal length = wider angle = greater field of view
larger focal length = narrower field of view = things look zoomed-in

Don't compare "zoom" in cameras, or just the focal lengths. Compare their field-of-view = 35 mm equivalent focal length.

Long story:

The pictures were taken using Nikon D40 (referred to as D40) and Panasonic Lumix DMC-ZS7 (referred to as ZS7).

On SLR's the lenses can be changed and we generally don't talk of zoom we talk of focal length of the lens being used.
On point-and-shoot cameras the lens is fixed and they are advertised with a zoom and not generally with the focal length.

For the D40 I have two different lenses. One has a focal length range of 18-55 mm and the other one 55-200 mm. The 55-200 mm lens is shown below.

Fig.1. The 55-200 mm focal length lens for the D40.

Using the two lenses I can take pictures at any focal length in the range 18 mm to 200 mm.The focal length changes the field-of-view (FOV) or angle-of-view of the picture you get, or the scene you see in your LCD or the view-finder, or the magnification or the zoom. I will just talk of the FOV or angle-or-view and leave the magnification and zoom.

Simply put, smaller the focal length, more is the FOV = you get a wider FOV. Larger the focal length, smaller is the FOV.Consider the four pictures shown below. All were shot using the D40 mounted on a tripod. So the position of the camera was (approximately) the same for all the pictures. The focal lengths for these four pictures were (in the order: upper-left - upper right - lower right - lower left) 18mm 55mm 100mm 200mm.

Fig. 2. Pictures taken at different focal lengths using the D40. The camera was mounted on the tripod so the position of the camera was (approximately) the same for all the pictures.

The picture taken at 18mm has a much wider view than the one taken at 200mm. However at 200mm the camera has zoomed-in on the bicycles. So, you want the bicycles along with the trees and the parking lot = you want a wide angle = use a shorter focal length. If you want just the bicycles use a larger focal length (or move close to the bicycles).

Now onto the point-and-shoot camera.

The zoom is basically the maximum focal length divided by the minimum focal length. On the lens of my ZS7 the focal length range is mentioned as 4.1 - 49.2. This corresponds to 49.2/4.1 = 12 i.e. "12x Optical Zoom". The picture below shows the front of the ZS7 where the focal length is circled in red.

Fig.3. The front of the ZS7 showing the focal length range of 4.1 - 49.2 thus the 12x optical zoom.

The focal length cannot be compared across cameras directly. This is because if I put the 55-200 mm lens for my D40 on another camera then the FOV might not be the same. The way lenses are compared (in terms of their focal lengths) is by looking at what FOV they will provided if they were mounted on a 35mm camera (basically mounted on the same camera, the 35mm camera is the standard everything is compared to).

For my D40 the "crop factor" is 1.5. This means that if I put the 55-200 mm lens on the 35 mm camera then the FOV I will observe will be the same as that provided by a lens of focal length range of 55-200 mm x 1.5 = 82.5-300 mm made for the 35mm camera. So a focal length of 200 mm for my lens for the D40 is equivalent to 300 mm on a 35 mm camera.

Now for the ZS6 the "35 mm equivalent focal length" is mentioned in its specifications as 25-300 mm. Similar as above, what this means is that if this lens on the ZS7 (4.1-49.2) were put on a 35mm camera then the FOV it will provide will be the same as a 25-300 mm lens made for the 35mm camera.

So a focal length of 200 mm on my D40, and a focal length of 49.2 mm on the ZS7 are both equivalent to 300 mm on a 35 mm camera. Thus a picture taken at a focal length of 200 mm using the D40 and one taken at 49.2 mm using the ZS7 should have the same FOV. The picture below shows a comparison. The picture on the left was taken using the D40 at 200 mm and the one on the right was taken using the ZS7 at 49.2 mm.

O yes I did make a mistake. With the ZS7 I was taking the picture using the 4:3 aspect ratio, for comparison with the D40 I should have switched to 3:2 but I forgot. But you do get the idea of the field of view comparison (compare horizontally).

Fig. 4. Field of view comparison for D40 (200 mm = 35 mm equivalent of 300 mm) and ZS7 (49.2 mm = 35 mm equivalent of 300 mm)

So DSLR or point-and-shoot cameras

smaller focal length = wider angle = greater field of view
larger focal length = narrower field of view = things look zoomed-in

Don't compare "zoom" in cameras, or just the focal lengths. Compare their field-of-view = 35 mm equivalent focal length.

Some trailers (animation)

2011-02-12T11:49:00.000-08:00

Clean using the clone tool

2011-01-28T23:56:00.000-08:00

Here is a picture I took of a dog on a beach:

Fig. 1 Original image.

I like the picture. The only problem is that it has spots. Some of these are marked with red circles in the image below.

Fig. 2 Original image with some of the spots marked in red circles.

These were caused due to dust on the lens and sensor of my DSLR. I freely change lenses on my DSLR not caring much that dust might enter the camera body, so this is expected. I did clean my lens and the camera later on, but what about this image. Well, one way to clean it up in post-processing is by using the "clone" tool. The cleaned-up image is shown below. The clean-up is not complete, but you get the idea.

Fig. 3 Cleaned up image after using the "clone" tool.

Another example is shown below. The picture on the left is the original picture and has a lot of spots. The cleaned up image (after using the clone tool is shown on the right). I think I even adjusted the "levels" because of which there is a slight difference in color. But you do get the idea of the clean-up.

Fig. 4 The original (on the left) and the cleaned-up (on the right) images.

So this is one of the situations where you can made good use of the cloning tool. How to use the tool ? You can find a lot of tutorials on the internet. Or simply check the help section of your image editing software. Or let me know and I might write about it sometime later.

McAfee's Knob hike

2011-01-01T23:05:00.000-08:00

The sun was out. The sky was not so cloudy. Temperatures were expected to reach in double digits (in degree C). It was a day for outing. Biking had been done the previous day. So I decided to go hiking to the McAfee's Knob.

It had snowed a couple of days back so there was a concern about the trail condition. However, the previous day I was told that the actual trail was fine for hiking and that the shout-cut was not. But yes, since it had snowed, parts of the trail were not dry. So I packed an extra pair of shoes and three pairs of socks. All of them were fully utilized. I took the actual trail while going up and combined part of the trail with the short-cut while coming down.

Here are some of the pictures which I took. All the pictures were taken by the Panasonic ZS7. Below some of the pictures I have noted the time at which they were taken. That might give you some idea about how far the things are and how long it might take to come across a landmark.

All these pictures (except for one) were taken during this (winter) trip. In the summer its all green and much more beautiful.

Hope you will be able to join me next time.

The starting point is from the parking lot off VA-311.

(11:51 am)

There you will see the sign for the Appalachian trail parking, and a brown board pointing (across the road) towards the trail for the McAfee's Knob.

On the other side of the road there is the board which points towards the trail.

White marks on the trees help you keep on the trail.

In the beginning, there was some snow on the trail.

Soon you will reach the start of the actual trail.

(12:02 pm)

From there on just keep going. Do remember the white marks on the trees.

There are a couple of wooden bridges, some big rocks, wooden step like portions on the trail. They will come pretty soon, at least the bridges. If not, you are going somewhere else.

(12:09 pm)

(12:17 pm)

You will come to a post which will point you to the direction of the campsite and a shelter. Keep going towards the campsites.

(12:42 pm)

Soon you will reach the campsite.

(12:44 pm)

While on the trail and looking at the campsite on the right, you will see the board on the left which mentions McAfees Knob, Tinkers Cliff and US220. Facing the board, you have to go straight (remember the white marks on the trees)

Maybe I should have made some arrows on the picture below. You will reach this place where the short-cut crosses the trail for the first time. It does so one more time, rather the second time it simply merges into the trail. The short-cut in the picture below, is running from left to right and the actual trail goes straight through.

(12:51 pm)

At one point you will cross a clearing with the wires (over your head, far above your head) and electric poles to the far left and right of the trail. Keep going straight.

(1:03 pm) Looking left, trail, looking right.

Keep walking. There was some snow on parts of the trail but it was not bad.

Finally, you will reach your destination.

(1:22 pm)

The view from the top is great. You just have to be there and see for yourself. You can find tons of pictures on the internet. A video which I made that day:

http://www.youtube.com/watch?v=7rGuMd8WR1k

The picture below is from the summers.

You can even see Tinker's Cliff from the top.

Adding a border to an image in Gimp

2010-12-30T19:40:00.000-08:00

A couple of years back I was asked how I put the borders in the images which I upload. Back then I used to do it the long-way. Soon after I had replied, explaining this long procedure, I found a much easier built-in option in Gimp, to do the same thing. Recently, I was asked the same thing again. So here is how to put a border in Gimp.

(1) Open the image in Gimp

(2) Under the "Filters" menu go to "Decor" and select "Add Border"

(3) In the "Script-Fu: Add Border" window which will show up, you can select the border size (X-size and Y-size). I always set the "Delta" value equal to 1. For an explanation of this or any other item you can click on "Help"

(4) You can click on the blue colored box to select the color you want for the border.

(5) Once you are done with all that, click on "Ok" and the border will be added. To clearly see the added border, just pull the main window of Gimp so that the complete image is contained inside the main window.

(6) Now you can save the image. I prefer using the "Save As" option in order to keep the original copy.

(7) When you try to save the image, Gimp will give a message saying "JPEG plug-in can't handle transparency" (I was saving it as a JPEG file). Click on "Export".

What does the message mean ? Well if you just want to add borders, you don't really need to know that.

(8) Finally Gimp will ask you one more question regarding "Quality". The default will be 100 (if not ,then set it to 100) and click on "Save", and you are done.

Here is the final image:

F-Number the bare minimum

2010-11-06T15:11:00.000-07:00

If you are trying to get out of the "Auto" mode and try new things here is a brief introduction on what the F number means and the use of setting the aperture value.

How well exposed your final picture is depends on primarily three things (a) aperture (b) shutter speed and (c) ISO.

Light passes through the aperture. So the size of the aperture matters.

Light will be allowed to pass and will be captured by the sensors for the duration of time set by the shutter speed. So the value of the shutter speed matters. If the shutter speed is 1/100 sec then the camera captures whatever it sees for 1/100 sec. This is even referred to as exposure time.

Light will be received by the sensors (for the duration set by the exposure time). So the sensitivity of the sensors matter. This can be set by the ISO value. Lower the ISO value lower is the sensitivity.

The size of the aperture is mentioned in terms of F number. All that you should remember is (1) larger is the F number more is the distance over which things appear to be in focus (2) larger the F number smaller is the aperture opening. This is illustrated in the picture below.

The left picture was taken at a F number of 5.6 and the right one was taken at a F number of 36. The focal length and ISO values were same for both the pictures. For the smaller F number (5.6, left) only a small strip of the ground seems to be in focus and everything else is out-of-focus. For the larger F number (36, right) a larger area is in focus and the blur is not so much. A technical term you might hear in this relation is "depth of field" that's the depth over which everything is in focus. So basically,

Smaller F number (left image) ==> Smaller area in focus and more blur = smaller depth-of-field
Larger F number (right image) ==> Larger area in focus and less blur = larger depth-of-field

But you will note that the exposure time (or the shutter speed) for the left picture is 1/125 sec which is shorter than the exposure time of the right picture 1/3 sec. This is because of the following:

Smaller F number (left image) ==> Larger aperture opening through which light can pass ==> To get a well lighted image, exposure time can be small.
Larger F number (right image) ==> Smaller aperture opening through which light can pass ==> To get a well lighted image, exposure time has to be longer.

That's all. What exactly does "F/5.6" mean ? Why does a larger aperture causes only a small area to be in focus ? etc. etc. all that for a later time.

About Panning

2010-10-23T17:04:00.000-07:00

First remember that all said and done it's all about having fun

I'm not an expert on panning, but thought that to keep this blog alive I will write something. So why not about panning.

Don't let the "right technique" "the rules" "the perfect exposure" etc. worry you too much. Experiment, click and have tons of fun.

The idea

Take a picture of a moving subject with the subject frozen and the background blurred.

Here is how it works

(1) You focus on a moving subject.
(2) Track the subject while keeping it in focus.
(3) Press the shutter while still moving the camera.

A few things you need to know

(1) If you are taking such pictures right at the road side then be prepared for some suspicious looks.
(2) If the shutter speed is too fast then nothing will be blurred and everything is simply frozen.
(3) If the shutter speed is too slow then keeping your hand steady might be a problem.
(4) Plus you need to track the subject nicely. Say you are taking a panning picture of a car. If your hand holding the camera is moving too fast it won't work. If it moves too slow it won't work. It moves up and down you will get something different. In all these cases everything will be blurred.

On my Nikon there are 3 auto-focus points which can be seen as small boxes through the view finder. When taking a panning picture of a car I typically frame the shot such that for e.g. the car window is in one of these boxes. Then when I need to move the camera for the panning picture, I try to move the camera such that the window stays right in the box. That just helps me check if I'm moving the hand too fast too slow, up or down.

Here are some hand-held panning pictures which I took today evening.

Panasonic Lumix DMC ZS7 pictures

2010-10-09T18:05:00.000-07:00

I recently bought the Lumix ZS7. When considering a point-and-shoot camera the final choice was between Canon Powershot SX210IS and Panasonic Lumix DMC ZS7. A friend of mine went for the former so my choice was made easy.

My thought: Panasonic Lumix DMC ZS7 is a good camera.

The LCD of the Panasonic Lumix is great. The downside however is that the pictures look much more bright and crisp on the LCD in comparison to what they look when viewed on my laptop. On my desktop however, for which I have a much bigger and better display the pictures look more closer to the ones displayed on the LCD. Also, the pictures displayed on the LCD are towards the saturated side.

About the pictures: All were taken at 12 Megapixels. For uploading all were resized to 1024 x 768 using Gimp. No other editing has been done. If you want to see the original sized image or want to know the EXIF information then let me know.

Do remember that ZS7 does have the aperture priority, shutter priority and the manual mode. However the pictures here are taken mostly using the auto mode and some using the program mode. Basically using it simply as a "point-and-shoot" camera.

(1) "iA" mode with flash off: simply point-and-shoot

All these pictures were taken in the "iA" (intelligent Auto mode). The only option which I set was for the flash to be off. In the iA mode the camera does seem to "blow out" the "highlights" i.e. the bright parts are too-bright. This is most visible in the outdoor pictures. But I think that is done by a lot (if not all) of the compact cameras. If you see some noise in the indoor pictures its mainly due to the ISO being higher as its selected by the camera itself. You can force the ISO to its least value in the "P" mode.

(2) "iA" and "P" modes

"iA" - intelligent-Auto mode. The camera selected all the settings I just forced the flash to be off.
"P" - Program mode. I set the ISO to 80 in order to have least noise. All the rest of the settings were selected by the camera.

"Intelligent contrast" and "intelligent resolution" option available in the "P" mode were set to "Off".

Here are the comparisons of pictures taken using the iA and the P mode. The description follows the image.

Taken using the iA mode

Taken using the P mode.

Taken using the iA mode.

Taken using the P mode.

Taken using the iA mode. Here the bright portions are kind of too bright.

Taken using the P mode. Here in addition to setting the ISO the exposure compensation was set to -1 1/3 to make the picture less bright in comparison to the one in the iA mode.

Taken using the iA mode.

Taken using the P mode. Here in addition to setting the ISO the exposure compensation was set to -1 to make the picture less bright in comparison to the one in the iA mode.

(3) Outdoor in the sun, indoor with flash and the issue of "highlight clipping" i.e. bright (white) areas being too bright

Highlight clipping = bright areas being too bright kind of blown-out is a common thing. My old Sony DSC-W1 had this issue. My Nikon D40 has that issue. How much is that an issue is, well, camera dependent. Here I'm uploading some pictures which were taken using the ZS7.

Remember:
(a) All these pictures were taken in the Auto mode.
(b) All compact cameras suffer from highlight clipping.
(c) You can easily get better results simply by switching to the "P" mode and forcing the picture to be under-exposed (EV value -ve). That is no rocket science.
(d) Mostly pictures come out best in soft lighting condition not during sunny afternoons, or when the subject is too brightly lit.
(d) In some of the pictures I think the camera did what any other compact camera will do.
(e) Do not make decisions based on just these pictures as you have nothing to compare these to.

Descriptions follow the pictures.

Taken in the iA mode, well lit conditions.

Taken in the iA mode, outside, on a sunny afternoon.

Taken using the iA mode, inside well lit conditions.

Taken in the iA mode, no flash, late in the afternoon. The blinds on the window were open. Here you see the bright window area being too bright.

Taken in the iA mode, indoor, late in the evening, flash = on.

Taken in the iA mode, indoor, late in the evening, flash = off.

Saving the Sunday morning

2010-09-12T07:42:00.000-07:00

Lets write something. Another attempt at saving the blog.

Slept rather late. When I woke up, lighted red straight lines said 7:55. Not too bad. But the Sunday morning needed to be saved. What better than to go biking. Breakfast ? Lets skip it.

Checklist: Water, Tang, raisins, glasses (Note to self: please don't loose them again)

Looked like others were up early.

The road was nice and welcoming as always.

The start of a nice down-slope. Try not to have too much fun.

The down-slope ends with an even nicer up-slope. Now why did I get off the bike here ?

It was not because of the bridge and water though.

Seems like colors are changing.

Ok now we again have a lovely down-slope which will be followed by an equally lovely up-slope followed by a couple of not so lovely up-slopes. So lets keep the camera inside and concentrate on biking.

Book list

2010-06-11T09:06:00.000-07:00

A list of seemingly interesting books which I came across while passing my time in the new-books section of our library, was told about by some friend etc. etc. Haven't read all of them. There is no specific ordering here.

J. Heine and J-P. Praderes (2005) "The golden age of hand-built bicycles"
S. Wolpert (2000) "A new history of India"
B. Russell (1968 first, 1995 revised edition) "Unpopular essays"
Greg Mortenson and David Oliver Relin (2007) "Three cups of tea".
C. K. Prahalad (2005) "Fortune at the bottom of the pyramid".
J. Diamond (1999) "Guns germs and steel - the fates of human societies"
A. Adiga (2008) "The white tiger"
M. Gladwell (2008) "Outliers - the story of success"
M. Gladwell (2005) "Blink - the power of thinking without thinking"
J. B. Taylor (2009) "My stroke of insight - a brain scientist's personal journey"
A. Levitsky (2008) "Worlds apart an anthology of Russian fantasy and science fiction"
J. Krause (2008) "Photo idea index - places"
T. Ang (2008) "Digital photography masterclass"

William Dunham (1990) "Journey through genius: the great theorems of mathematics" (This is a keeper)
J. Kakalios (2006) "The physics of superheroes" (Great for introductory physics and makes me want to read comic books)
M. Hoagland and B. Dodson (1999) "Patterns - sixteen things you should know about life"
B. Bryson (2003) "A short history of nearly everything"
C. Sagan (1997) "Billions and billions"
S. Hawking and L. Mlodinow. () "Briefer history of time"
P. Atkins (2003) "Galileo's finger : the ten great ideas of science"
George Pólya (1962) "Mathematical discovery; on understanding, learning, and teaching problem solving".
George Pólya (1954) "Mathematics and plausible reasoning".
F. Hidetoshi and T. Rothman (2008) "Sacred mathematics - Japanese temple geometry"
Martin Aigner, Günter M. Ziegler (2003) "Proofs from THE BOOK".
(2004) "Sherlock Holmes in Babylon : and other tales of mathematical history"
Frank E Burk (2007) "A Garden of Integrals"
C. Alsina and R Nelsen (2009) "When less is more: Visualizing basic inequalities"
M. Levi (2009) "The mathematical mechanic: Using physical reasoning to solve problems"
J. A. Adam (2009) "A mathematical nature walk"
J. Bryant and C. Sangwin (2008) "How round is your circle? Where engineering and mathematics meet"
S. Kalajdzievski (2008) "Math and art - an introduction to visual mathematics"
M. Hoagland and B. Dodson (1998) "The way life works - The science lover's illustrated guide to how life grows, develops, reproduces, and gets along"
D. E. Smith () "A source book in mathematics"

W. W. R. Ball (1939) "Mathematical recreations and essays"
A. H. Beiler (1966) "Recreations in the theory of numbers : the queen of mathematics entertains"
J. D. E. Konhauser, D. Velleman and S. Wagon (1996) "Which way did the bicycle go? and other intriguing mathematical mysteries"
K. Kendig (2008) "Sink or float? Thought problems in math and physics"
L. Weinstein and J. A. Adam (2008) "Guesstimation - solving the world's problems on the back of a cocktail napkin"
R. Honsberger (2004) "Mathematical delights"
R. Honsberger (2003) "Mathematical diamonds"
R. Honsberger (1991) "More mathematical morsels"
J. Havil (2008) "Impossible? surprising solutions to counter-intuitive conundrums"
J. Martineau (2002) "A little book of coincidence"

On the Gaussian assumption

2010-06-02T14:40:00.000-07:00

This had been pending for over an year now.

Issue:
In many cases for a random variable, given the knowledge of the first two moments (i.e. mean and variance) and faced with the need of assuming a probability density function (pdf), it is common to taken it to be Gaussian.

What I knew:
The assumption of Gaussian distribution in many cases can be justified on the basis of the central limit theorem. Also, the Gaussian pdf is completely characterized using the first two moments i.e. the mean and variance.

Another reason which I came to know while reading about estimation and filtering:
Given the mean and variance the Gaussian distribution has the maximum entropy.

Ref:
Catlin, D. E. (1988) "Estimation control and the discrete Kalman filter", Springer.
Shannon, C. E. (1948) "A mathematical theory of communication" (As available in the pdf format from: http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html).

"Which way did the bicycle go?"

2009-12-24T14:52:00.000-08:00

Problem: If you are given the plot of the tracks traced by the front and rear wheel of the bicycle, how will you tell which direction the bicycle was going? For e.g. consider these two figure

In these two figures, how would you decide which direction the bicycle was going i.e. right to left or left to right ? What would be the idea or basis behind your method ?

I came across this problem while reading the book "Which way did the bicycle go? and other intriguing mathematical mysteries" by Joseph D. E. Konhauser, Dan Velleman and Stan Wagon, published by the Mathematical Association of America. As mentioned in the preface of this book, it is a collection of some 190 problems taken from the "Konhauser collection". The problems are grouped under six main topics (plane geometry, number theory, algebra, combinatorics and graph theory, three-dimensional geometry, and miscellaneous) each of which has further sub-groups.

As for the level of mathematics needed, I have not gone through the full book but based on the problems which I have read, I think mathematics up to 12th standard might be enough. Get the book and have fun solving problems.

Making part of the image black and white in Gimp

2009-12-20T09:15:00.000-08:00

Here is a way of making a part of the image B&W in Gimp. The basic idea is to select the portion which we want to change and while keeping it selected, make the changes. In case the part which needs the change is the major portion, it might be easy to select the rest of the portion and then invert the selection. Here I will let the speed and roundabout sign in yellow remain as it is and make changes to the rest of the figure.

(1) Open the image in Gimp

(2) Select the "zoom" tool

(3) Zoom-in on the yellow sign by repeatedly clicking on it

(4) Select the "path" tool

(5) Using the path tool draw the outline of the yellow sign. You will notice that as you click, small circles will be made at the point where you click. Also, the latest point is connected to the previous one making a "path". In order to end or close the path, after you have gone all around the sign, click on the very first circle.

(6) Now from the "select" menu click on "from path"

(7) When you do so the circles and dash line made by the path tool will all be connected, and you have a dash (moving ant like) line on the outline of the yellow sign.

(8) From the "select" menu click on "invert". As of now everything inside the path is selected, with "invert" everything outside the current selection will be selected.

(9) Use the zoom tool to zoom-out to see the full image.

(10) From the "color" menu select "desaturate"

(11) In the picture everything except for the yellow sign will turn B&W. Also you will be presented with three options of how to desaturate. You can click on each and see which you like best.

(12) Now that its B&W, for a final touch we can adjust the contrast. To do so, from the "color" menu select "brightness and contrast".

(13) Use the slider to increase the contrast to the level you want.

(14) Finally, from the "select" menu click on "none" to remove any current selections.

(15) Now that its done, it may be saved in this final version.

There are other methods of doing this but for this image I think this is the simplest way.

The dust particle that occupied my mind

2009-12-08T22:56:00.000-08:00

Problem

Using my Nikon D40 I took some pictures and in all of them I could see a spot in the middle.

I could see a spot both (a) when looking through the view-finder and (b) in the final picture. Haven't found out how to get rid of the spot on the view-finder but will tell how to do that if its caused by some dust particle on the sensor.

Testing for dust particles on the sensor

This is what I read on the internet. I don't remember the exact advise and reasoning but this is essentially what I did after reading that page.

(1) Set the focal length to maximum.
(2) Set the aperture to minimum.
(3) Set the focus (manual) completely off.
(4) Take a picture of a blank white sheet.
(5) Look at the picture and check for black/grey spots.

In my case, I could anyway see the spot in the final pictures, but when I did this then the spot was more prominent.

The solution: Blow air and clean the sensor/filter

Long story short here is how the spot in the final picture was removed.

(1) Things needed - Camera, air blower, enough light to look at the sensor/filter area.
(2) Better to have a fully charged battery.
(3) Remove the lens from the camera body.
(4) Turn the camera on and from the setup menu set the "Mirror lock-up" option to "On".
(5) Set the camera mode to manual.
(6) Change the shutter speed till you reach the "Bulb" mode.
(7) Now press the shutter button and keep it pressed.
(8) The mirror will give way to the sensor/filter area.
(9) Look at the sensor/filter surface. In my case I could clearly see a speck of dust in the center of the surface.
(10) Use the air blower and blow air on the sensor/filter area while holding the camera upside down (so that dust can easily fall vertically down).
(11) Release the shutter button.
(12) Switch the camera off.
(13) Put back the lens, take some pictures and see if it helped.

Happy clicking.

Song info - 순정만화 (Hello Schoolgirl)

2009-08-07T21:49:00.000-07:00

Movie - 순정만화 (Hello Schoolgirl)

There is a song in this movie which plays in the background while Ha-kyeong and Sook are having dinner for the first time in the restaurant right after they catch the last train. The song remains in the background while Ha-kyeong and Sook are talking and comes in the foreground for maybe 10 seconds. I wanted to know which song this was and finally with the help of some friends I was able to find it. The song is "바이러스 - 이영진" or "Virus - Lee Young-Jin". It is not listed in the OST of this movie but can be found in the listing of the OST of "Crazy Waiting".

Also, some have asked about the song which plays in the trailer for this movie. That song can be found in Youtube by looking up - Minusul 100% romantic - it will be the first result.

I forgot I had opened an account here

2009-07-15T07:02:00.000-07:00

I just now realized that at some point in time I had opened an account on Blogger. As I had then suspected this blog of mine has almost died. I find it easier to upload pictures on Picasa and Flickr than to type here. Though the initial plan was to even post pictures here with some explanations as to why I took them and what was the idea I had in mind. Lets see if that can be done.

Here is the link to an article I came across on "The New Yorker" titled "How David Beats Goliath" :
http://www.newyorker.com/reporting/2009/05/11/090511fa_fact_gladwell

Hibernation option when you click "Turn Off Computer"

2009-04-15T15:01:00.000-07:00

Operating system (which I use): Windows XP Professional

Issue: When I go to the "Start" button and click on "Turn Off Computer" I see three options, "Stand By" "Turn Off" and "Restart". If I'm at this screen its always to turn the computer off, but where is the hibernation option ? I do have "Enable hibernation" checked in the power options.

Solution: Press the "Shift" key and the "Stand By" option will change to "Hibernate".

The international street fair 2009

2009-04-08T16:03:00.000-07:00

This weekend we had the International Street Fair. Another fun event at Virginia Tech. It gave me an opportunity to take my camera for an outing. I had in mind a particular type of picture which I wanted to take. A performer performing some dance routine and the picture taken with a shutter speed fast enough to freeze the performer but slow enough to get the motion blur in the performers dress. However the too bright sunlight did not allow me to do that. Shooting in the RAW format I ended up filling the memory card and by then it was anyway time to pack up. Some of the pictures which I took have been uploaded and can be viewed at:

http://picasaweb.google.com/saurabh.bisht/InternationalStreetFair2009#

Fallen Angels

2009-03-15T11:39:00.000-07:00

Movie: Fallen Angels

You can easily recognize the similarity in style between this movie and Chungking Express. Both are directed by Wong Kar Wei. Not much action, or talking between characters takes place in the movie. Most of the times its the characters "thinking out loud". There are several scenes of and from fast moving trains or subways. Plus the scenes where the characters are on the run have the blurry effect added to it. Overall I liked it.

One of the best things I liked about the movie was the song "Mong Gei Ta" (singer: Shirley Kwan). Loved the song, bought it on iTunes. Most likely had it not been in the movie I would not have come across it.

Happy Holi

2009-03-10T18:10:00.000-07:00

A very Happy Holi to everyone. Wanted to make this picture more realistic. But by the time I got this much done other things came up which needed attention.

Music shopping

2009-03-08T20:40:00.000-07:00

Finally I bought the song "November rain" by Guns and Roses. The next in line is most likely "Stairway to heaven" by Led Zeppelin.

movies movies movies

2009-03-08T17:50:00.000-07:00

Movie watching activities. Just now I will just list some of them. Will try to add some descriptions and my thoughts maybe next time.

Title: The Other Boleyn Girl (English)
Starring: Natalie Portman, Scarlett Johansson, Eric Bana and others
Director: Justin Chadwick
Won't call it a waste of time but won't watch it again.

Title: The visitor (English)
Starring: Richard Jenkins, Haaz Sleiman, Danai Jekesai Gurira, Hiam Abbass and others
Director: Thomas McCarthy
Ok. Kind of slow.

Title: Chungking Express (Hong-Kong)
Starring: Takeshi Kaneshiro , Brigitte Lin, Tony Leung Chiu Wai , Faye Wong and others
Director: Wong Kar-wai
This was different. I had read somewhere on the internet that the style of the movie was different and in a way the first of the kind. It is different and watch it to know what's different. Will watch it again sometime before returning the DVD.

Title: Righteous Kill (English)
Starring: Robert De Niro, Al Pacino and others
Director: Jon Avnet
This was not at all time well spent.

Title: Spring, Summer, Fall, Winter...and Spring (Korean)
Director: Kim Ki-duk
Kind of slow but some really good landscapes.

Title: God Grew Tired of Us (English, Documentary)
Director: Christopher Dillon Quinn
Liked this documentary.

Title: Priceless (French)
Director: Pierre Salvadori
A good-time-pass.

Title: The valet (French)
Director: Francis Veber
A good-time-pass.

Title: The King of Masks (Chinese)
Director: Wu Tianming
I would really like to see people perform the masks trick in real life.

Title: The Edge of Heaven (German/Turkish)
Director: Fatih Akın

Title: Caramel (Lebanese)
Director: Nadine Labaki

from Confession of a Dangerous Mind

2009-03-02T14:21:00.001-08:00

From the movie "Confession of a Dangerous Mind", wordings might not be exactly correct:

"When you are young, your potential is infinite. You might do anything, really. You might be Einstein. You might be DiMaggio. Then you get to an age where what you might be gives way to what you have been. You weren’t Einstein. You weren’t anything. That’s a bad moment."

An article and a book

2009-02-28T11:58:00.000-08:00

Was reading a friends blog and following some hyperlinks reached the article on Forbes.com titled "India Has The Brains, But Where's The Beef?". Here is the link:

http://www.forbes.com/2007/08/05/india-higher-education-oped-cx_prg_0813education.html

Also, came to know of this book "The fortune at the bottom of the pyramid" by C. K. Prahalad. Will probably get it from the library this afternoon.

Update: Installing XP on Lenovo X61s with Vista

2009-02-21T09:41:00.000-08:00

I installed Windows XP by changing the S-ATA mode from AHCI to Compatability in the Bios. Now I want to change it back to AHCI. If you do it then Windows won't boot up and shows the blue screen.

The solution can be found on Lenovo's support website:
http://www-307.ibm.com/pc/support/site.wss/document.do?lndocid=MIGR-70477

Installing XP on Lenovo X61s with Vista

2009-02-18T18:42:00.000-08:00

Objective: The Lenovo X61s laptop came with Microsoft Vista OS. Now I want to format the hard disk drive, create new partitions, and install Microsoft Windows XP.

Problem: If you try to boot from the XP installation CD it does not recognize the hard disk drive.

Why the problem? : The hard disk drive on the laptop is SATA. After reading on the internet it turns out that the SATA hard disk drive is not recognized by the XP installation CD.

Solution which worked for me: You can surely browse the internet and can find other options, for e.g. the F6 option. But here is what I did. At startup I entered the Bios settings and locate the SATA option. It has two choices, AHCI mode and compatibility mode. The AHCI mode was selected. I changed it to compatibility mode. I have no idea what AHCI or compatibility mode means or for that matter what SATA means. But switching to the compatibility mode allowed the XP installation CD to recognize the disk drive and it did the installation. Its all up and running now.

How about the drivers ? Lenovo did not send drivers or programs CD's. So the easy and fast option was to downaload the XP drivers for X61s from their website.

Got all the programs ? Well besides the DVD burning software, the other programs (ThinkVantage programs) are available through Lenovo's website. Will have to buy the DVD burning software I guess. Or maybe call Lenovo and ask them for the CD.

So what about that SATA options in Bios ? Well, I have to confirm from some reliable source but reading on the internet it seems that the AHCI mode has some advantages. But I have doubts if they really make any difference for an average PC user.

A word of caution : If after you install XP you switch the SATA setting back to AHCI mode Windows will not startup. You will receive (atleast I did) the Windows blue screen with some error message.

See also the post "Update: Installing XP on Lenovo X61s with Vista"

Chinese spring festival

2009-01-28T16:20:00.000-08:00

This past weekend the Association of Chinese Student and Scholars (ACSS) organized the Chinese Spring Festival function to celebrate the Chinese New Year. This year its the year of the Ox. The function was fun, though I did not understand most of what was being said (my Chinese is rather weak). The above picture is a collage with some of the pictures I took.

The duckpond at VirginiaTech

2009-01-10T16:03:00.000-08:00

The campus of VirginiaTech is really beautiful. One of my favorite places to visit on this campus is the duckpond. I go there regularly and since I bought my first DSLR this frequency increased. You obviously find ducks there. They are used to seeing people. Though not with cameras but rather with packets in which they have something for them to eat. Last weekend I tried to take a picture of one when it was flying and was about to touch the water in the pond. I did not get that one but did get one of a calmly swimming one.

The new year card

2009-01-04T16:00:00.000-08:00

So the new year is here. First of all a very happy new year to everyone. Lets start with a new year card I made. Initially the plan was to print it out and send it as an actual card. However that never materialized beyond the "plan" stage. Here is the card though.

The main background image is the bokeh image taken in my room. For that I hung some colored lights over my desk and took an out-of-focus image. To this I added two firework pictures and finally the text. Maybe next year I will send out actual new year cards instead of e-mails.