Its fun to play with light. Light has so much color and "texture". I bought this strange looking glass bowl at an antique shop. They were selling it as an ashtray. I figured I could use it to hold candles. 

This Tuesday I finally got my driving license in the US. Well, I technically don't have the license itself yet - it will be mailed to me eventually. Since I had a rental car at my disposal, Kyle and I decided to take a little photography trip. We drove to Lake Lemon, a few miles from Bloomington.

We reached the lake a little before sunrise. It had been years since I saw a sunrise, and the quality of the light was just fascinating. Its true what professional photographers say - there is quite nothing like the morning light. Also, wild geese make lovely subjects.

I usually don't shoot in black and white. Kyle almost always does. Here is my attempt to look vaguely Ansel Adams-ish. The picture below looks a lot better in full resolution. So the hi-res version of the picture is uploaded, you just need to click on it.

Finally, to add a bit of color, here is Lake Lemon a few minutes before sunrise. This too is better hi-res, but in the interest of server space I am uploading only the little version here.

Most photographers I talk to, who are hobbyists like me, act a little strange when the topic of post processing comes up. A manner that is rather reminiscent of a stupid friend letting slip something in front of your parents. They look a little squeamish and then they start to feign innocence. "I never post process my pictures", "Oh! that's how it came out of the camera", "I want my photos to be *real*", "Only minimally, just yadda yadda yadda..." etc.

What?

What are you all uptight about? What's the big deal? Do you realize that when you take a digital photograph there is a lot of software in the camera making choices for you already? I haven't done much (if any at all) post processing so far, not because I have anything against it, but because of (1) I don't have the tools and (2) It takes too much time. I do have Picasa on my machine and every now and then I have tried boosting saturation on a picture or cropping out an annoying detail and have felt good about it.

The problem with Picasa is that it doesn't allow much control over things and I still end up wasting a lot of time if I ever start playing with it. Many many years back I had access to a copy of Photoshop and that program simply made me feel stupid - I couldn't get it to do anything. I remember Abdul Rafeeq who was in my undergrad engineering class and was a wiz with Photoshop. Rafeeq used to design all our posters and such, so I had first hand evidence of the fact that the tool was powerful in the right hands. (The only image manipulating program I felt good about was Gimp - the fact that I never installed it and that I never really used used it, made me feel really good about myself. Once in a while I'd find some poor soul struggling with it and feel a deep satisfaction that it wasn't me.)

Enter Adobe Lightroom. Lightroom is a post processing tool designed primarily with the interests of photographers in mind. The tool is designed to let you select and organize pictures, do a decent set of color corrections, tone fixing etc type operations that most photographers are interested in.

I downloaded a copy a few days back on the 30 day trial period and I like it. Its a bit slow, not as responsive as Picasa, but is otherwise rather nice. After playing around with it a bit, I must say I like the added power to fix the color settings of my pictures. Being able to boost color in your pictures (or de-saturate them) is an added dimension of power. Of course, it cant make a bad picture good, but it does compensate for the color of the light, the white balance settings, the nuances of your cameras sensor etc. As a matter of fact, once I get comfortable with this I suspect I will be able to get the look I want without much trouble as well.

Comparing the detail of someone's forehead. Which one do you think came out of the camera and which one is the post processed version? The odd looking reddish hue, the one on the right, is the version that came out the camera.

The downside? The several hundred dollar price tag. Its cheaper than Photoshop but its a bit too much for what the PhD program pays me.

Part 1 - DOF and Aperture

If you haven't read my photography disclaimer, take a look .

Before we start, here are links to one or two external DOF articles:

http://www.mir.com.my/rb/photography/fototech/htmls/depth.html

This link shows some of the math behind the graphs that I plot here. I find it useful to see the graphs plotted in this article to visualize these relationships. You may find the tables they have handy.
http://www.conent.com/ConAdv/Encyclopaedia/Photography/CNQ_CAPhotography001.asp 

Continuing from where we left of (Part 1 - DOF and Aperture), lets take a look at the relationship between DOF and distance to the object being focused on a little more closely. In the previous graphs we could get some insight into this relationship. Here we will plot distance on the x-axis and DOF on the y-axis.

The two graphs above show the DOF changes for the fixed aperture value f/4 and focal length of 50mm. The first graph shows the variation of DOF over a relatively short distances of <5m. The second graph shows how this varies over greater distances and show the non-linearities in the DOF when greater focusing distances are involved. From a distances of about 20m DOF start shooting up and by ~30m you get infinite DOF.

Lets throw in some more aperture values and see what we get. f/1/4, f/1.8, f/2.8, f/4.0, f/5.6

Nothing very interesting happening with the shorter distances. The larger distances show the larger fstop numbers curving off sooner. This is consistent with the idea that the greater the aperture (i.e. lesser the f-stop value) the lesser the DOF. If you have a lens that can provide f/1.4 you get a rather nice DOF control even upto distances of about 50m! The Canon 50mm f/1.4 prime that costs about 300$ should do that. The much cheaper Canon 50mm f/1.8 prime would be expected to follow the green curve - rather sweet for a 80$ lens.

Lets look at some larger f-stop values.

At f/22 even in distances under 5m we see the DOF curving up. From roughly 5m to 20m for the aperture range of f/5.6 to f/22 we start to get infinite DOF.

Now lets vary the focal length a bit, starting with some wide shots.

These are plotted for a f/4 aperture. Within 5m each of these DOF graphs curve upward to infinity. At 10mm, if you are focusing on something that a little over a meter away you get infinite DOF! If you are wondering how 10mm is relevant, the Rebel line of cameras support the EFS mount and currently the widest (non-fisheye) lens you can get if the Canon 10-22mm lens - its a beauty.

Lets look at some medium range lengths.

25mm curves upward at roughly 6m. The longer the focal length, the narrower the DOF. A 50mm would curve upward at about 30 meters.

At small distances all these focal length's are very well behaved. You get very narrow DOF and with a good lens, you should get a great bokeh! Each of these focal lengths only reluctantly yield to large DOFs. So if you need to zoom into something thats 50m away and need an infinite DOF, you need to stop down the aperture. :)

There you go. The graphs should show roughly the real world values that you should expect to see with your equipment. You might want to take some approximate readings off these graphs and then go out in the field and see how these values work for you.

In the next part (whenever I get down to writing it), we'll plot the remaining combination  - DOF against focal length.

Last week I watched Stanley Kubrick's 1975 classic, Barry Lyndon. What a movie! I haven't seen a movie with as gorgeous realistic photography in a while. Kubrick's composition is perfect, every single shot. The lighting and the story telling is awesome.

Barry Lyndon is the story of the life of a curios Irish character, Redmond Barry, who goes onto become the wealthy 'Barry Lyndon'. It is a 3+ hours epic, that is enjoyable right through. Its a nice tale and the way it is told is excellent. A must watch, with some wine and cheese.

As someone with an interest in photography, I am stumped by how Kubrick achieved some of the shots in this movie. The rich colors, the way the light looks... In some ways the film was a bit of a photographer's dream project. Most scenes were shot in natural light - legend has it that the film didn't use much artificial lighting at all. In fact the beautiful candle lit scenes in the movie were shot in actual candle light alone.

Quoting from http://www.visual-memory.co.uk/sk/ac/len/page1.htm:

At the very early stages of his preparation for "BARRY LYNDON", Kubrick scoured the world looking for exotic, ultra-fast lenses, because he knew he would be shooting extremely low light level scenes. It was his objective, incredible as it seemed at the time, to photograph candle-lit scenes in old English castles by only the light of the candles themselves! A former still photographer for Look magazine, Kubrick has become extremely knowledgeable with regard to lenses and, in fact, has taught himself every phase of the technical application of his filming equipment. He called one day to ask me if I thought I could fit a Zeiss lens he had procured, which had a focal length of 50mm and a maximum aperture of f/O.7. He sent me the dimensional specifications, and I reported that it was impossible to fit the lens to his BNC because of its large diameter and also because the rear element came within 4mm of the film plane. Stanley, being the meticulous craftsman that he is, would not take 'No" for an answer and persisted until I reluctantly agreed to take a hard look at the problem.

The lens that is spoken of here is one that the famous lens manufacturer Carl Zeiss made for NASA. Not many of us can get our hands on 0.7 aperture lens today, even for still photography. As a matter of fact I don't know of any that are commercially available. Canon's 50mm prime at f/1.8 is 80$ (USD), the f/1.4 version of the lens is about 300$ and there is a L class f/1.2 lens which is about 1,300$. It stops there it doesn't go any lower. Canon once had a f/1.0 lens, which I believe is now discontinued.

Now that I look around, its 2nd on the "Ten Movies Every Photographer Should See" list. The first is, of course, Baraka.

Part 2- DOF and Distance

If you haven't read my photography disclaimer, I recommend you read it now.

Photography with SLRs essentially involves navigating the multi-dimensional space created by many variables - aperture, shutter speed, ISO, exposure (ev), DOF, noise, focal length, focusing distance etc. In part, your effectiveness as a photographer depends on how well you understand this space and how well you can navigate it.

In this writeup I look at DOF. Before you read this article, I expect you already know what DOF is, and that you have some experience trying to control it. Browse around and a bit and read about DOF before you look at this article. Know what the terms mean and such. Here are two little articles that you introduce some terminology for you.

http://www.dofmaster.com/dofjs.html
http://www.dpreview.com/learn/?/key=depth_of_field

Here are some slightly more explanatory articles:

http://www.luminous-landscape.com/tutorials/understanding-series/dof.shtml 
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

Most books, like Bryan Peterson's popular "Understanding Exposure", give you a some perspective into DOF, how aperture affects DOF and how to use it creatively. I have always been a bit confused by depth of field because it never seemed to work quiet the way I expected. I always seemed to me that DOF relationships are not linear in the space of the variables that affect it. What I mean by that is that when I change a variable that affects DOF, say the aperture, it does not seem to change DOF at the same rate.

So what variables affect DOF? As best as I know they are not just aperture, but include aperture, focal length, focusing distance and camera type. Look at the URLs above, they have  DOF calculators there that accept values for these variables and give you various DOF values back. What we are going to do here is to plot some graphs between these to better visualize how one variable affects another. My graphs are based of the equations that run the DOF calculator on dpreview and are hence only as accurate as those equations are. What value you get out of this depends on how closely you look at the graphs and try to visualize what the curves mean in terms of actual photography.

This time we are going to look at the most frequently expressed relationship, that of DOF and Aperture.

The graph below shows DOF plotted against aperture for a focal length of 50mm and focusing distance of 1m (ie the object that you are focusing on is 1m away). This plot is for the Digital Rebel XT (the EOS 350d) and should hold for any 1.6x senor DSLR such as the Rebel, Rebel XTi and such.

The aperture has been varied from f/1 to f/32. Assuming we (ever) have an affordable lens at f/1. There are two lines in the picture. The lower one corresponds to the nearest point that will be in focus and the upper one corresponds to the farthest point that will be in focus. So at f/4, the region of focus starts at roughly 2.5cm in front of the point of focus and extends to about 2.5cm behind it. The total DOF at f/4 is about 5cm.

Since you are at the same position with respect to the object you are photographing and that focal length is 50mm throughout, changing the aperture will affect the depth of field and exposure time (the shutter speed) needed to maintain the same exposure value.

Notice how the graph tends to curve a bit? Lets see how the DOF curve looks when plotted at different distances. Here are the curves for some smaller distances all in the same graph.

For each focusing distance there are two lines, the lower one being the nearest point in focus and the farther one being the farthest point in focus. Some interesting things to note: 1) The DOF does not increase very much if you are focusing on close objects. 2) For short distances, of under a meter, the DOF seems to grow linearly.

Lets look at some greater distances.

Here the non linearities become very apparent. This graphs plots DOF curves at distances of 1 to 5 meters. Look at the y-axis, note that each unit corresponds to 2 meters. The pair of green lines representing the two meter focusing distance seems to increase almost linearly. At 3 meters, aperture values of 22 and above have rather large farthest points of focus.

The general trend is this: at greater focusing distances the father point of focus increases exponentially on increasing the aperture. In fact its worse than just exponential, the values hit infinity relatively quickly. So at focusing distance of 5m at f/22, the farthest point of focus has hit infinity.

Lets look at some greater distances.

At larger distances, smaller apertures lead to infinite DOF values. At 50m, f/4 already gives you infinite DOF! Even at 10m, there is a region of focus that is about 4-5m at f/4. Another way to look at this is that DOF tricks make sense only if the object in question is relatively close to you - i.e. within 2 or 3 meters. Well, that's not entirely true - we haven't heard what focal length has to say about it. But it does seem true at 50mm.

Here are some greater distances that show degenerate version of the above curves.

Now lets go back to the first graph where we were at 1m and 50mm focal length. Lets look at some graphs that show the effect of changing the focal length. Along the x-axis we still vary the aperture value and on the y-axis we plot the DOF. We are just going to draw multiple graphs based on changing the focal length (while keeping the distance fixed).

So at wider apertures, the DOF increases. The effect of going from 50mm to 60mm, visually will also be that the object occupies a larger part of your frame. This is roughly what you get were you to stay at 50mm and step closer to the object. From this can we conclude that if the object stays roughly the same size in your screen, the DOF stays the same? I don't know yet. But the graphs seem to indicate so.

Let look at some wider focal lengths. The widest non-fisheye lens one can get for the Rebel series is the 10-22mm lens. (Its an awesome lens btw.) So lets start plotting at 10.

At 10mm f/5.6, we have already hit infinite DOF even when the object is just 1m away. At 18mm we hit infinity at about f/15. At 18mm and f/4 we have a decently small area of DOF, however remember how easily this degenerates based on your distance graphs? So if you want to take advantage of DOF when you are at the wide end, you must be pretty close to the object and have a wide open aperture (the smaller the numeric value of aperture, the larger is the actual aperture i.e. more light is allowed onto the sensor).

Lets look at some longer ranges.

Notice that the units of the y-axis have changed. At longer ranges (70mm to 120mm) the DOF stays small and concise, good enough to bring out that beautiful bokeh. Greater zooms have narrower DOFs - I don't bother to plot those graphs here. Its easy enough to imagine how they'd look.

So what do we have to take away. DOF does increase with aperture, but usually only for short distances. For greater distances there is non-linear increase in DOF often hitting infinity. Similarly at wider focal lengths you get a larger DOF for the same aperture. On increasing the focal length DOF does get narrower until some point where the DOF-aperture relationship starts to look linear again.

Distance from the object and the zoom (focal length) both DOF inversely. Increasing distance increases DOF and increasing zoom decreases it. In other words, if you were to step back but zoom in tighter to compensate, the increased distances and the increased zoom might compensate for each other giving you roughly the same DOF. (I would be able to assert this with some certainty if I have equations for the size of the image on the sensor.)

That said, if you want to take a picture whose beauty depends on DOF and you are willing to vary the object size in the final image (maybe you can compensate by cropping?), understanding the relationship between distance/zoom and DOF will come in handy. In the later parts of this write-up I hope to go into that. Let me know what you think.

Part 2 - DOF and Distance

I am not a professional photographer. I am pursuing my PhD in theoretical Computer Science and I enjoy photography. Nearly all I what I have to say about photography comes with my experience with my EOS 350d that I have had for about 2 years, at the time of this writing. Hence take my opinions and suggestions with some discretion.

The art of "painting with light" has many ingredients. There are matters of spirit that each person brings - your aesthetics, your sense of beauty, your evaluation of what is worth shooting, etc. And then there are aspects of photography that involve understanding the nature of the machine and laws that govern it. To the latter part, I realized only recently, that I can apply my relatively abundant geekiness, potentially compensating part of my shortcomings in aesthetics. Hence my blog entries about photography.

Of course, some have more skill.

I got my new baby this Friday. The Canon 24-105 L:

Friday was a busy day - meeting with Dybvig, Sabry and Michael Adams, followed by attending some of the Preparing Future Faculty conference talks, followed by a talk about "Exploiting Online Games" by Gary McGraw, followed by a talk about "A Theory of Hygienic Macros" by Dave Herman. I rush home after all of this to see the Amazon package at my door. Quickly unpack, eyes gleam, say "my preciousss..." for sometime and then quickly rush out for dinner with some of the PL folk.

Initial impressions - the lens is build like a tank. Its also fairly solidly built. Its thick and relatively short, with a filter diameter of 77mm it dwarfs the camera. In fact, one of the most solidly build lenses I have seen. Had it been not such a crime to the lens, it might even be used as weapon of self defense. "He was bludgeoned to death with a 24-105'. "Quid pro quo Clarice, you indeed do have a maniac on your hands".

This is also the first lens with which I feel I can manually focus with some reliability. The little viewfinder on the 350d is indeed limiting, but a good lens seems to make a lot of difference.

All that said, I have been able to play with it much. Bloomington has been real windy this weekend at -8 degrees Celsius. One can dress for the cold, but wind at that temperature is just too much. You hands freeze into numbness in no time. This makes me say "NOESS FAIR!" in lolcat style.

Despite this, I manage to take a short walk one day. The pictures below are uploaded full size as they came out of the camera without any sort of out of camera processing. The quality of the images is impressive, take a closer look.

Sunset over the Dunn meadow, Bloomington, IN.

East wing of Swain Hall, the building that houses the joint Computer Science, Math and Physics library.
Bloomington, IN

Kyle told me about this stuff and it seems so unbelievably cool.

http://graphics.stanford.edu/papers/lfcamera/

Like Kyle says, "probably the coolest invention in photography since film".

Also, http://scpv.csail.mit.edu/levoy.htm

The video they have linked on their website is worth watching after you have had a look at the web page.  This stuff is on youtube as well, linking it in here (though the quality of the direct avi file is arguably better):

I wonder how long it will be till we have this in cameras that we can afford to buy - 15 years?

An amateur photographer's perspective.

Disclaimer: I am not a professional photographer. I am doing my PhD in theoretical Computer Science and I enjoy photography. I got my Rebel XT roughly 2 years back and that's the limited experience with which this is written. Hence take my opinions here with some discretion.

Canon EF 70-200mm f/4 L USM

Canon EF 70-300 f/4-5.6 IS USM

Why the comparison?

These lenses are worth comparing because they cost roughly the same ( Amazon: Canon 70-200 L , Amazon: Canon 70-300 IS ), about 550$ on Amazon at the time of this writing. They are not "cheap" lenses, they are both reasonably good ways to add telephoto capabilities to your arsenal. If you don't have a telephoto lens and you are tight on cash, one of these is a good choice. They differ slightly in what they offer. (If you have lots of money you may want to get the Canon EF 7-200 f/2.8 L IS USM .) Towards the end of this article are urls to reviews about both lenses.

For the past few days I have been playing with Kyle Ross's 70-200 L. I have been comparing this beauty against my 70-300 IS which I have owned for about a year.

The Canon 70-200 is an L class lens. Canon gives the "L" rating to only its very best lenses. It would seem like a no-brainer that one should get the 70-200 lens as opposed to the non-L 70-300. Well, maybe not. What is good for you largely depends on what sort of photographer you are.

These lenses differ on various aspects. The ones I'd like to talk about here are - build quality of the lens, aperture and range, image stabilization and overall image quality.

Build Quality:

The 70-200L is built like a tank in comparison to the 70-300. Its a real pleasure to hold. As a matter of fact, everytime I pick up my 70-300, after I have been shooting with the 70-200, I feel that its about to break. What that means in practical terms is that you need to carry around the 70-300 rather delicately. The 70-200 could last a lot more rough handling than the 70-300 would. Are you the sort of person who will remember to put your backpack down carefully everytime?

In its defense, this is what I have to say: I don't have a special camera bag or pouches for my lenses. I carry my lenses as is in my shoulder bag along with my text books and the camera body. I remember to not throw my shoulder bag around but to place rather carefully on the ground when I am carry lenses.The 70-300 has been fine so far with this sort of of handling, so its not exactly a flimsy lens.

The 70-200 is also much larger and heavier than the 70-300. (I tried to scale the images of the lenses above such that they roughly reflect their relative sizes in real life.) This will make a difference when you start carrying around several lenses. Most photographers end up carry around 3 lenses on the average - a wide, a medium and a zoom.

The last point about build quality I want to mention is that the 70-200 does not extend when you zoom. It is a fixed length lens. The 70-300 on the other hand extends out. So when you back in the lens you have to remember to unzoom all the way. It might be better leave the lens on manual focus when you are carrying to reduce any strain on the externally moving parts of the lens.

If you get a 70-300 you will have to be willing to take care to treat it gently. Also, it does not come with a lens pouch - that will be extra. The 70-200 on the other hand does come with a pouch and a hood.

Aperture and Range:

Having a constant aperture across the full range of the is a big deal. At 300mm the 70-300 can only provide a 5.6. At 200mm it can provide 5.0. The 70-200 can provide an aperture of 4.0 throughout. In practice this makes a nice difference. Going down from 4.0 to 5.0/5.6 make a difference in the DOF/bokeh quality and in the exposure time that you have to endure when shooting indoors in low light.

The 70-300mm on the other hand can provide an extra 100mm of zoom. In practice the difference between zooming from 150mm to 200mm seems to be a much greater difference than zooming from 200mm to 300mm difference. Hence though the extra 100mm may seem to be a big deal, its not that much.

While the loss of aperture and the loss of range are not really comparable, if I had to comment on it I would say that they are roughly comparable. Getting that little extra range is roughly equal to getting that little extra aperture. What is better for you will depend on what sort of shots you tend to take. If you don't have a telephoto, you have no way of knowing this.

I am personally slightly biased in favor of the extra range. When shooting distant things, it does indeed give you that extra bit of detail. There isn't very much softening of the image even at 300mm as well.

Canon 70-300 at 300mm, f/5.6.

The 70-200, being an L class lens, is compatible with some of Canon's lens extenders. These increase the range of the lens with slight reduction in image quality. I have never tried one myself, so I am not sure what exactly the degradation is like. The extender are relatively inexpensive as well (under 300$). This is a way to make up for the lost range. As far as I know, the 70-300 isn't compatible with these extenders.

Image Stabilization:

In short, the IS is fantastic. Zoomed in at 200mm its nearly impossible to handhold most shots unless you are shooting in bright daylight. At 300mm things are even worse. This is where the 70-300IS wins hands down over the 70-200L which has no IS. The only way you can shoot handheld with the 70-200 is under ideal lighting conditions or by jacking up the ISO as high as it will go. Even then the lighting is sometimes not enough for the typical indoor evening scene.

I am disappointed with a large number of my 70-200 shots simply because of camera shake. At those zooms its really hard to hand hold a camera because even the slightest shakes will reflect significantly on the picture. Maybe you have super stable hands, but I doubt anyone can handhold these well enough.

The IS on the other hand enables you to shoot one or two (sometime three) f-stops below what you can without it. This is a huge difference when it comes to taking indoor or evening pictures.

The difference between having IS and no-IS largely depends on what sort of photos you are planning to take. Are you mostly going to be shooting in situations where there is enough light or where you can adjust the lighting? I like taking my camera everywhere - evening walks, friends houses, late night drives etc. Hence, this is not always an option for me. If you are going to be shooting in a studio or some such controlled environment, you don't have to worry about this.

The other alternative is to not shoot handheld at all, but to use a tripod. A good tripod is expensive - a ball head is expensive too. Secondly its heavy and a headache to carry around everywhere and setup. Thirdly, the time taken to setup and compose a shot sometimes makes all the difference between getting the shot or not at all. So, while having the tripod is a solution, its a solution that comes at a significant price in terms of time, money, effort etc.

Even with the IS, there are some shots that I just can get. I don't have a tripod and the trick I use is to set the camera down somewhere and to use a remote to take the picture, thereby avoiding camera shake while clicking. Canon makes a good simple remote for about 24$.

Sometimes despite the IS, both lenses are comparable in low light. Sometime back I was trying to take pictures of some small objects in my living room which has rather low light. I wanted to get a close to the objects as possible to take these shots. As it turns out, the minimum focusing distance for the 70-200 is lesser that that of the 70-300. Hence I could stand closer to the object and take the picture at 200mm at f/4.0 and ISO 1600. With the 70-300, I had to stand further away from the object. Hence I had to zoom in to 300mm to get the same detail, this meant that the f-stop drop to 5.6 and the IS has to struggle with the extra zoom and smaller aperture giving me roughly the same image quality (the 70-300 being sightly better). Cases like this are very much the exception and normally the IS adds great value.

Canon 70-200L at 200mm, f/4.0, ISO 1600, handheld, lowlight, Rebel XT

Canon 70-300 at 300mm, f/4, ISO 1600, handheld, lowlight, Rebel XT

Image Quality:

This is a tricky topic to discuss simply because it has so many facets. We tried to compare the lenses under ideal conditions, shooting outdoors on a slightly cloudy morning. We stopped down both lenses to f/8.0 took some test shots at various zoom settings. If there are any differences in the image quality they were really really hard to tell. In fact just casually looking at the pictures we got, its hard to make out any differences at all.

When zoomed in, there are some differences, especially towards the edges of the images. The 70-200L seemed to do marginally better in this regard. But these differences are so slight that I tend to discard them - in actually photography there are many more things that constitute to making beautiful pictures than such slight differences. If you did a lot of very controlled photography, then maybe these differences matter to you. For my relatively cavalier style of photography, these don't matter at all.

Due to the f/4.0 of the 70-200, some pictures shot at the 200mm end tend to look nicer that the those shot with the 70-300 simply because of the depth of field. I sometimes tend to think that the 70-200's picture have a bit more contrast.

On the other hand, the 70-300 delivers really good image quality even at 300mm - something that the 70-200 simply can't do. Cropping an image to the 300mm equivalent does not preserve enough detail to make them comparable. Also having the IS means that a lot of the pictures come out much sharper with the 70-300. Given a tripod the 70-200 may actually outperform it; but that's a whole other argument.

One last note about image quality is about the usage of polarizers. The 70-300 has a rotating front element. This makes using polarizes rather annoying because they keep spinning around. Polarizers are sensitive orientation and hence after you have focused you have to switch to manual and carefully correct the polarizer before each shot. If using polarisers is important to you, the 70-200 maybe a better choice.

Final thoughts:

Both lenses are fairly well balanced overall. The loss of an f-stop on aperture as opposed to 100mm on range. A better build quality as compared to IS. The take roughly the same quality pictures under ideal settings. What is better for you depends largely on what kind of photography you do. Do you have the luxury of a controlled environment or carrying a tripod? If yes, then the 70-200L is for you. Do you like to wander around and take pictures without much ado? If yes, then the 70-300 is for you.

I own the the 70-300 myself and I absolutely love it. I bought it at a time when I did not have anything to compare against. I wish it were better built and I hope it survives my irreverent handling for many years. Having played with both lenses would I still get the 70-300? Probably yes. However, I feel that in a few years when I developed more taste and style (and own a space-age tripod) my answer may change.

Here are some external reviews of these lenses:

The 70-300 IS:

http://photo.net/equipment/canon/70-300is/
http://www.bobatkins.com/photography/reviews/canon_EF_70-300.html
http://www.bobatkins.com/photography/reviews/ef_70_300is_review.html
http://www.the-digital-picture.com/Reviews/Canon-EF-70-300mm-f-4-5.6-IS-USM-Lens-Review.aspx
http://www.fredmiranda.com/reviews/showproduct.php?product=294&sort=7&cat=27&page=3

The 70-200 L:

http://www.the-digital-picture.com/Reviews/Canon-EF-70-200mm-f-4.0-L-USM-Lens-Review.aspx
http://www.bobatkins.com/photography/reviews/ef702004l.html
http://photo.net/equipment/canon/70-200
http://www.fredmiranda.com/reviews/showproduct.php?product=14&sort=7&cat=27&page=3

My first L-class lens, the Canon 24-105mm L f4.0 IS USM. In short, L-class lenses are Canon's very best lenses. For a while now I have been trying to get lenses for the wide and long end of the spectrum leaving the medium ranges to my now-pretty-much-defunct 50mm prime. I was hoping to stretch and get a real good medium range lens one day. Now it looks like its happening... yay!

This lens is a keeper. I don't think there is something I can think of buying that will replace the utility of this lens. Except maybe if I can ever afford something like the 28-300mm L (which costs 2000+ dollars and would still be clunky to carry around). It was hard deciding between this and the Canon 24-70mm L 2.8 lens, but I eventually decided in favor of the extra range and the IS. My experience with the Canon 70-300 IS USM that I have is that IS is very very handy in low light situations (being a relatively pedestrian photographer, I find myself in low light situations wanting to take pictures rather often, sans a tripod). I can always make up for the aperture by getting a few nice primes, but that can wait.

One of the things I enjoy about Windows Vista is the slideshow gadget that comes with the OS. I have pointed the slideshow at my external hdd folders where most of my photos live. Hence this keeps playing back randomly selected thumbnails from my rather large photography set. This brings back rather nice memories at times.

Bloomington is rather cold today (its reached -14 degrees Celsius as of now) and I was thinking about warmer places I have lived in. As chance would have it, the slideshow brought up a picture of the Charminar in Hyderabad. I remember squinting to take this picture in the bright afternoon sun.

The Charminar, Renovations - March, 2005.

From http://en.wikipedia.org/wiki/Charminar

The monument was built by Muhammad Quli Qutb Shah in 1591 to commemorate the eradication of plague, shortly after he had shifted his capital from Golkonda to what now is known as Hyderabad [1] . Legends has it that the emperor Quli Qutb Shah prayed for the end of plague and took the vow to build a masjid on that very place. He ordered the construction of the masjid which became popular as Charminar because of its four characteristic minarets (possibly depicting the first four khalifs of Islam). The top floor of the four-storeyed structure has a masjid which has 45 covered prayer spaces and some open space to accommodate more people in Friday prayers. Madame Blavatsky reports that each of the floors was meant for a separate branch of learning - before the structure was transformed by the imperial British administration into a warehouse for opium and liqueurs. [2]

True to the legend, the city blossomed into a synthesis of two cultures. In 1591 while laying the foundation of Charminar, Quli prayed: Oh God, bestow unto this city peace and prosperity. Let millions of men of all castes, creeds and religions make it their abode. Like fishes in the water.

I have been reading this Ansel Adams classic at a leisurely pace and have been enjoying it greatly. He uses the word "make" as opposed to "take" for the photographs he creates. And truly, what wonderful photographs he makes.

From the chapter on "Rose and Driftwood":

Most of my photographs made before 1930 were of distant grandeurs. But as I learned the inherent propperties of camera, lens, filters and exposure, I also gained the freedom to see with more sensitive eyes the full landscape of our environment, a landscape that included scissors and thread, grains of sand, leaf details, the human face and a single rose.

I am begining to see this difference in 'making' pictures, I am only begining to make mine, though I have 'taken' many.

I have been seeing this guy outside my apartment for the past 2 years now. Every once in a while I see him dart under the bushes or wait apprehensively to see what I would do. So the other day when I saw him looking rather relaxed on the grass, I decided to shoot him.

Canon 350D, Canon 70-300 4-5.6 IS at 300mm (35mm equivalent is 641mm!!), exposure 1/250, f/5.6, ISO 1600, handheld.

Btw, he is not just any rabbit, he has a name - Jack.

This is an antique shop in a little west of the Bloomington town center. I have never really seen this store open - it has been closed everytime I passed by. I have wondered about this building every time I have passed by. Its a bit of a spooky building and I was wondering if I might be able to hold our weekly Programming Languages group meetings in there, the building would lend a nice ambience to our usual topics - dependand types, syntactic abstraction, denotational semantics and such.

This is also one of my first 30 sec exposure shots. It was taken with my 350D at 10mm (Canon 10-22mm) , f/8.0, ISO 400 and exposure time 30secs. I didnt have a tripod on me that I would like to use (I really need to get another tripod, one that can support the weight of my camera and which is a ball-head instead of the maddening mutli-directional adjustment thing), so I had to set the camera on the ground with the lens facing slightly upwards. Also it was so dark when I was taking the shot that the autofocus completely failed and I could not tell if the structure was in focus or not using the manual focus. The view-finder on a Rebel XT leaves a lot to be desired.

For a long time now, I have been taking pictures without knowing the details behind many things. Of late I have been looking at some photography books to better understand the technicalities and boy, has it been fun!

Same settings as the previous shot, but with -1/3 stop exposure bias.