Category Archives: Tests

Testing the Canon 5D II for Noise

From Night Photography blog by Andy Frazer: More 5D Long Exposure Tests:

Seattle-based night photographer Brian Chapman has posted another set of 5D MkII long exposure tests, this time all taken at night. Although this set was taken at ISO 400, underexposed, and then pushed during RAW conversion, the results are very interesting.

Brian Chapman’s experiments are essentially a night photographer’s torture test – shooting at high ISO, underexposing, compensating in post, adjusting the image, and including areas of uniform color and luminosity. If you aren’t familiar with real life noise issues in digital photography you might think, “Ugh! Noise.” If you have done night photography and made prints for images like those in the test you might be thinking, “Hey, that’s pretty darn impressive!”

Shooting Active Subjects With a Long Lens

Although I’m not an expert on the subjects of sports photography or bird photography (or “BIF,” as aficionados write) using really long lenses, I have had some opportunities to pick up some skills in these areas recently. Since one of my photography contacts recently wrote and asked for some advice about using a longer lens to photograph birds, I thought I’d share a bit of what I’ve found to work for me.

First, if I were specializing in these types of photography I would likely use different equipment than what I currently have. For example, I know that many folks find the big prime telephotos to be ideal for their work and some prefer the very large, heavy, and expensive large aperture versions. Great lenses for sure, but not exactly suitable for what I do – so my long lens is a Canon EF 100-400 f/4.5-5.6 L IS. I shoot a full frame Canon 5D. This is a great camera for urban and wild landscapes and other types of photography that I tend to do, but it would not typically be regarded as ideal for the type of shooting I’m writing about today. Something with a faster burst mode might be better for those focusing on this type of shooting, and in many cases the advantages of full-frame might be outweighed by other factors.

That said, what have I learned so far? In no particular order, a list:

  • Hit rates can be quite low. If you are the kind of photographer who likes to think a lot about The Shot before pressing the button, or who gets frustrated when not every shot is good – get over it. You are going to take a lot of bad photographs, but you’ll eventually start to get better and to get some good ones.
  • The Sprint, Santa Rosa - 2008 Amgen Tour of California
    Tracking moving subjects takes practice. A lot of practice. In many ways it is like learning a sport – you need to do the thing many times, fail many times, begin to succeed, and learn from the process. The first few times I tried panning with a pack of bicycle racers my success rate was terribly low – lots of shots of rear wheels, tilted way out of horizontal and so forth. Eventually I began to smooth out the panning process, reserve a part of my attention for keeping the camera more or less level. Eventually I had more success when I focused up putting the center of the subject in a certain part of the frame, rather than just aiming and hoping.
  • Turning off all focus points except the center AF point can help. I find this to be especially true with birds in flight. Unless the background is clear sky the camera will often AF on everything but the bird. With only one AF point active the trick becomes getting it on the moving bird, but if you can do this you’ll focus on the right subject.
  • 20080217_5981GDanMitchell.jpg
    Sometimes pre-focusing can be your friend. In particular with sports that follow a set path – like bicycle racing time trials – you may have more success by applying your careful analytical skills to setting up a shot. Find a good location, pre-focus on a place where the rider will likely be and turn off AF, begin tracking the rider before arrival at the pre-focus spot, and fire away. This can work with birds in flight, but in practice I find it much less reliable there since the darn birds tend to fly all over the place. However, you can sometimes determine that birds are following a particular route and position yourself accordingly. Along the California coast the birds often seem to follow particular routes relative to tops of cliffs or rocks that extend into the water. Spend a few minute studying this and you may locate invisible “sky trails” that they follow.
  • Your camera’s “servo” mode may help in some cases, but it isn’t necessarily a panacea with subjects that really move fast. Sorry, you’ll have to figure this one out on your own. :-)
  • Burst mode can be your friend. When subjects move very fast – both in terms of their motion through space and in terms of they own motion of legs, wings, etc. – it can be important to get multiple images. Even the relatively leisurely burst rate of my 5D is very useful. But you still need to think a lot about timing the shots – just holding the shutter down without thinking will result in a very low hit rate. Sometimes it is still better to take just a single well-timed frame. I’ll often put the camera in burst mode but still sometimes only shoot a single frame.
  • The longest focal length is not always best. In fact, I don’t actually shoot my 100-400mm lens at 400mm all that often. In other cases I’ll use the 70-200 instead.

A few other perspectives I’ve picked up from using the longer lens and from shooting these wildlife and sports subjects:

  • Not all sports and wildlife shots require long lenses. In fact, some of the most interesting shots in both categories can take the opposite approach and use wide lenses.
  • Fisherman, Winter Surf (2)
    I’ve also learned more about how very long lenses can be great for certain types of landscape shots. Although I’ve always tended to think in ultra-wide, wide, normal, or shot tele terms when I do landscape, the first time out with the long lens I got a series of landscape shots that I could simply not have taken with the shorter lenses.
  • Developing the high speed thinking that you must do when you photograph highly active subjects can improve your photographic work in other areas. If you are comfortable framing a composition given a few minutes to think about it, trying to apply your composition skills to an image in which everything is in flux will really sharpen your “seeing” skills.
  • Working outside of your subject comfort zone – e.g. sports for the landscape shooter – has a bunch of positive effects. Not the least of these is understanding how these other subjects can be handled in a way that is every bit as aesthetically interesting as the subjects you may be comfortable with.

Sharpness Test Updated

I have updated my Sharpness and Aperture Selection of Full-Frame DSLRs post to include the corner crops from the same photos used for the center crops that were already there. Here’s the image I added – see the link for full information.

Corner Sharpness of the Canon 17-40mm f/4 L Lens on Full Frame

Since the question of how the Canon EF 17-40 f/4 L performs across the frame for landscape photography comes up periodically, I have posted an older test photo I made last year (2007) – updated here to include a comparison corner and center sharpness.

Canon5D17_40f16CornerVsCenter.jpg

Technical data: Canon 5D. Canon EF 17-40mm f/4 L lens. Focal length: 17mm. Aperture: f/16. Shutter speed: 1/60 second. Shot on the tripod with MLU and remote release. If the full image were reproduced at this resolution the print would be about five feet wide. (Not that I’d do that – it is a really boring photograph! :-) In a more typical size print the corners would like very good, indeed.

A 100% crop would not be expected to be “razor sharp” – and we see typical results here. It is impressive to see how well the corner image quality holds up – despite the fact that grass is one of the most challenging subjects for a digital sensor and the fact that this part of the scene was much closer to the camera than the focus point in the center of the scene – i.e. the corner section showing the grass is only a few feet from the camera, and the camera is focused hundreds of feet away on the objects in the center of the frame. (On that subject, I’m convinced that a good number of the reports of “poor corner performance” in ultra wide lenses are actually due to the subjects in the corner being much closer to the camera position than the subjects in the center of the frame, especially when the “tests” are done by shooting actual landscape subjects.)

BOTTOM LINE: What does this tell us, how do we view this in the context of reports of soft corners on the EF 17-40mm f/4 lens, and what does this mean for anyone trying to choose a wide (or ultra-wide in the case of full-frame cameras) Canon zoom lens?

While this lens is soft in the corners when shot wide open, the lens is not particularly soft in the corners when stopped down. If your primary use for such a lens is, for example, shooting very low light handheld wide angle photographs the 17-40 is perhaps not your best choice. (The EF 16-35mm f/2.8 on full frame or the EFS 17-55mm f/2.8 IS on a cropped sensor body could be more appropriate zooms.) On the other hand, if you are primarily interested in subjects that are usually shot at smaller apertures (urban/wild landscapes, architecture, etc.) then the 17-40 can be an outstanding lens – though this is more true on a full frame body than on a crop body, given that you are unlikely to use the smaller apertures on a crop sensor body given the diffraction blur issues there. So, to state it very succinctly…

… the Canon EF 17-40mm f/4 lens is an excellent lens for shooting deep DOF small-aperture photography on a full-frame camera. (It is OK but not necessarily ideal for use with cropped sensor bodies, where I would prefer the EFS 17-55mm f/2.8 IS.)

G Dan Mitchell is a California photographer whose subjects include the Pacific coast, redwood forests, central California oak/grasslands, the Sierra Nevada, California deserts, urban landscapes, night photography, and more.
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Text, photographs, and other media are © Copyright G Dan Mitchell (or others when indicated) and are not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.


Canon 24-105mm f/4 IS Lens Sharpness: An Example

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Canon EF 17-40mm f/4 L: Testing a Claim About Sharpness and Focal Length

Today I read a claim in a photography forum thread that “some 17-40’s are soft on the long end.” Having not noticed that on my copy I went back to some test shots I did earlier this year to compare sharpness at 40mm and 24mm with this lens.

The two images below are 100% crops – in other words, they are very small sections of a much larger print that would be something like 5 feet wide if printed at this resolution! The crop came from an area just below the center of the frame. Both were shot on a Canon 5D a 1/125 second and f/11. The camera was on a tripod and I used mirror lockup and a remote release. Both were converted from RAW using ACR with no adjustments to the original settings. The same sharpening process was applied to both.

24mm: 40mm:
17-40at24mmf11.jpg 17-40at40mmf11.jpg

My verdict? There doesn’t seem to be a lot of difference in terms of sharpness. And if there is a difference, it would hardly be significant in even a pretty decent sized print. I don’t think a difference would be noticeable in a 12″ x 18″ inch print, and frankly I doubt that anyone would notice even at a larger print size.

What do you think?

There is one other possibility. The person who posted the original message claimed that “some” copies of this lens exhibit this problem. There is no way for me to rule that out with only one sample.

One other related idea. Any zoom lens is going to perform differently at different focal lengths, and there will likely be some focal length or focal length range in which the “quality” may be measurably “best.” But this doesn’t mean that the other focal lengths are not good – in some cases so good as to provide virtually the same quality.

G Dan Mitchell Photography
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(Basic EXIF data is available by “mousing over” large images in blog posts. Leave a comment if you want to know more.)

A Test: Correcting Lens Distortion in Post-Processing

Earlier this weekend I read a forum thread about the Canon EF 50mm f/1.4 lens, of which I have a copy. The thread lamented the barrel distortion of this lens (which I don’t really find to be that big of an issue) and continued with posts suggesting alternatives including software correction in the post-processing phase. One response to this proposal was that software correction would degrade the  image and would therefore be unacceptable.

That theory seemed sound and I have believed this to be true in the past, but I decided to test this idea for myself. Using an old photograph taken with this lens, I cropped a small section from one of the far corners – the worst part of the frame and, according to some, subject to a lot of softness and distortion on full-frame bodies like my Canon 5D. To make things a bit more challenging I used a photograph that included a bunch of dried california grasses – full of very fine details and high contrast.

I converted the original RAW file using ACR (Adobe Camera RAW) with no sharpening. In Photoshop I cropped to a section of reasonable size for web presentation, using that section from one of the corners of the image. Then I made a duplicate of the cropped section of the image.

In one of the two versions of the crop I used the LensfixCI plugin to correct for the slight barrel distortion of the EF 50mm f/1.4 lens. This $29 plugin* includes a database of many lenses, and also keeps a smaller databases of your lenses. It uses EXIF data to identify the lens (and focal length with zooms) used to take the photo and automatically applies optimum distortion corrections from its database. It takes me about 10 seconds to select the plugin and apply its changes.

* (I have left the reference to this plugin that I used when I did the test several years ago, even though I no longer use it. Today I simply use the built-in correction in Lightroom or ACR, where I apply lens- based corrections by default in virtually all cases.)

Next I used my normal sharpening methods on both images, inspecting the results and making adjustments as I applied them. In the end, as would typically be the case, I used slightly different sharpening settings for the two images – but that reflects the normal way of operating. Finally, I took the two images and placed them side by side in the single high quality jpg file that follows.

Barrel Distortion Correction
Barrel Distortion Correction

(NOTE: The version shown above on this page has been downsized for formatting purposes and limits the amount of detail that is visible. Click the image to view it at its original size, or follow this direct link to the original image.)

I have a darned hard time seeing any difference in sharpness, contrast, or color that might have been introduced by the correction process. If a difference is visible a) it is almost impossible to say which version is better, and b) the difference is almost certainly completely insignificant in an actual print. (Keep in mind that these are 100% crops of the worst part of the frame in the far corner – and that the area shown here would be a very tiny section of a full print that would be something like five feet/60″ wide.)

After doing this test, I’m not really concerned at all about any negative effects of using this method of correcting lens distortions, and today I simply allow ACR or Lightroom to automatically correct for such lens characteristics by default. And whatever the tiny negative effect on sharpness we might imagine to produce, it is far outweighed by the ability to straighten lines and so forth when necessary.

(Anyone care to guess which half contains the “corrected” version of the crop? Feel free to post a comment and an explanation of what you (think you) see… ;-)

(This 2007 post was slightly updated on 1/5/2013)

G Dan Mitchell is a California photographer and visual opportunist whose subjects include the Pacific coast, redwood forests, central California oak/grasslands, the Sierra Nevada, California deserts, urban landscapes, night photography, and more.
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Text, photographs, and other media are © Copyright G Dan Mitchell (or others when indicated) and are not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G