Canon 100-400L 4.5-5.6 - The Infamous Beer Test - Is my lens too soft at 400mm?

Hello everyone,

So after getting some rather disappointingly unsharp images of Ospreys and Bald Eagles in flight with my new 100-400L, I decided to take the advice of Reyno and try the infamous "beer test:" I found a bottle of old Budweiser in the fridge, along with a can of Shasta and a freezer thermometer, set these items on top of the grill, set the 20D and 100-400L on a tripod precisely 30 feet away, and proceeded to zoom to 400mm and take photos at various ISOs and Focal Lengths. Judging from the images here (full image and 100% crops), is my lens too soft? Should it go back to B&H, or do I just need to learn how to properly use this lens? Thanks in advance for your help.

Here are the photos at 100 ISO:

100% Crop, F5.6:

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Here are the photos at 200 ISO:

100% Crop, F5.6:

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It appears a bit soft wide open, and then nice and sharp at 7.1

hard to tell though on that lousy subject matter. Try shooting a $20 bill. Much better fine detail, and you won't have the shininess of the can to deal with.

Might also run the front-rear focus test sheet too.

Lone Wolf 75,
ISO 100 or 200 shouldn't have a difference in lens sharpness. In your 200 ISO f/5.6 the photo is sharper with better white balance but not enough light, then the 100 ISO f/5.6 which has off white balance and 1/2 (or less) the sharpness.
I would bet this is due to user error.
Of course this is just my opinion

Here are the photos at 800 ISO:

100% Crop, F5.6:

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John_B wrote in post #3615942
Lone Wolf 75,
ISO 100 or 200 shouldn't have a difference in lens sharpness. In your 200 ISO f/5.6 the photo is sharper with better white balance but not enough light, then the 100 ISO f/5.6 which has off white balance and 1/2 (or less) the sharpness.
I would bet this is due to user error.
Of course this is just my opinion

Well, I did bracket all of my images -1/3 to +1/3. I was dealing with a crappy tripod too, so I picked the sharpest looking out of the lot, hence the difference in white balance between the images.

the ones that look really bad seem to be motion blurr. Did you have the IS off? Remember, it should be off on a tripod.

Yeah those results look pretty inconsistant, and the soft shots do look a lot like motion blur. If you don't trust your tripod, handhold it at your camera's highest sync speed and use direct flash - a sharpness test doesn't have to look good, it just has to be failsafe.

Crypto wrote in post #3616074
the ones that look really bad seem to be motion blurr. Did you have the IS off? Remember, it should be off on a tripod.

*Smacks Forehead* Of all the things to forget to do... Nope, IS was left on. Looks like I need to repeat the test.

Hmm...The first photo shot at f5.6 ISO100 looks OOF.....you may want to shoot couple more static objects to determine if it is the lens fault. This time use flash.

Also, from my experience of the 100-400 lens...to get really sharp image, I need to use at less the shutter speed that is twice the focal length. eg if I'm at 400mm, the Tv would be 1/800 with IS turned on (if hand held).

I have a Velbon Sherpa tripod which as always seemed to be quite satisfactory until very recently when I got one of the large L lenses (70-200) with a 2X extender to give me 400 mm maximum and I suddenly learned that the combination of the lightweight tripod and the massive lens do not work well together even though I use a remote shutter switch. The weight of camera and lens on this tripod can result in a lightly damped low frequency oscillation. While motion may not be visible to your eyes, it is nevertheless still there and can show up as a very tiny amount of fuzziness in the image. Even the shutter operation can send a vibration through a lightweight tripod. This does not mean that the lightweight tripod is not any good -- it just means that it is overloaded.

OP - your lens looks fine. That's the reassuring part. Your tripod does not - it actually takes a heck of a solid rig to hold it steady at that focal length, especially since the 100-400 is front-heavy. I use a Gitzo GT1530 and Markins Q3 head, and even then, that's considered not steady enough (Gitzo does not recommend >300mm on a Series 1).

The reason why I think it's the tripod is that your ISO 200 crop looks fine. With sufficient shutter speed and IS, it 'masks' the inability of the tripod to hold it 100% dead steady. ISO (by itself) is not expected to affect sharpness unduly.. well, as long it's reasonably low ISO and not suffering from excess noise. If your images sharpen up at higher ISO's it's probably due to the increased shutter speed.

I recommend what you do is put the lens on the sturdiest table you have, maybe something that can support your own weight and doesn't shake. Put a book underneath it to support the front end, then repeat the tests. Try using the self-timer (10 seconds) if you are concerned about shake.

I didn't see anyone mention IS(maybe I missed it). Did you give the IS time to settle? When I was micro-adjusting my 100-400 I saw soft images if I didn't give the IS a second to settle, or make sure it's off on a tri-pod.

Mine is also new, and from B&H. I'm very happy with its sharpness, and I've handheld all but my focus test shots, at rather low shutter speeds(200ish). You could have a bad one, but make sure your test is good first.

JohnC

Digital cameras have what is known as an anti-aliasing filter in front of the image sensor. It's put there to prevent moire and staircase distortion.. These filters introduce a degree of softness... The camera sharpens the captured image to compensate for the AA filter..

Usually the default camera sharpening isn't quite enough to overcome the softness introduced by the filter.. It's not uncommon to have to do sharpening after the fact... Most of the super tack sharp images you see on this forum have had some sharpening done during post processing.

FWIW, I've had my 100-400 for a couple of years now. I've found that at 400mm, an aperture of f9.5 is the sweet spot. It gives the sharpest images and the best bokeh.

Also.. Make sure you use the supplied hood. If you have bright light shining on the front lens, you may not see bright flare spots, but you will lose some contrast in the images. I get noticeably better results with the hood.