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I'm shopping for a 70-200 F/4 USM IS L, and took a few test shots with it.

Here's a 100% crop with a focus point highlighted.

  • It was shot handheld with IS on at 70mm / F4 / 1/400 sec.

  • In-camera picture style was set to Sharpening (3).

  • The image is NOT sharp as far as I can tell.

Am I being unrealistic in my expectation from the lens that gets the best reviews all over the place?

crop

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    \$\begingroup\$ I don't think that's a full resolution JPEG, it's not even 2 megapixels. \$\endgroup\$ Apr 3, 2011 at 22:20
  • \$\begingroup\$ i've uploaded the full-res image to another host, i guess tinypic downsized the image \$\endgroup\$
    – roman m
    Apr 4, 2011 at 0:04
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    \$\begingroup\$ Try uploading directly from the question edit form --- you should be able to upload a full-res picture with no hassles. \$\endgroup\$
    – Evan Krall
    Apr 4, 2011 at 2:43
  • \$\begingroup\$ The sample images are now gone. Roman, can you re-upload them using the image upload form? That way, they'll be here forever. \$\endgroup\$
    – mattdm
    May 30, 2016 at 16:18
  • \$\begingroup\$ @mattdm it's been forever, I don't have those any longer \$\endgroup\$
    – roman m
    Jun 1, 2016 at 20:06

4 Answers 4

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When performing a test to determine X its best to remove all the variables you're not testing for.

If you're wondering about the sharpness of your lens:

  • Shoot on a tripod
  • Use manual focus with live view for critical focus
  • Use mirror lockup
  • Shoot in RAW
  • Use a low ISO, at a reasonable shutter speed
  • Turn IS off
  • Shoot a well lit target

The problem with your example is it looks like your focusing was off (the 'B' looks much more in focus) which could mean you focused and then moved the camera slightly, the AF mis-focused because of a myriad of reasons, in camera processing did something weird, your body has back focusing problems...

Some of those things are your fault, some of them are the camera's fault and some of them are both your faults but if you want to determine where the cause of the sharpness problem is you need to narrow down the variables and test each thing individually.

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  • \$\begingroup\$ good recommendations, to which I would add - photograph a flat surface which is square on to the lens axis. \$\endgroup\$
    – labnut
    Apr 3, 2011 at 22:51
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    \$\begingroup\$ and a remote shutter release if you can get one... \$\endgroup\$ Apr 5, 2011 at 5:06
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That lens tests very highly for sharpness, even at its widest zoom and at widest aperture.

For a regular zoom lens I'd normally say don't get too excited about its perfromance wide open at the wide end, but with this lens it really should be very good.

My thoughts are:

  • Possibly a focus issue. This is the most likely reason. Try overriding the autofocus. Choose a particular part of the image you want to be in focus, as the depth of field is fairly narrow at that focal length and aperture.

  • Might as well put it on a tripod. This will also help ensure that you can focus and shoot without moving in between. Also, it's a heavy lens, so you may as well lock it down.

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Am I being unrealistic about image quality expectations from Canon 70-200 F/4 USM IS L Lens?

You're being unrealistic that shooting handheld using AF in less than ideal light is going to reveal anything that can be attributed only to the lens rather than any of the other factors that could be affecting image sharpness.

Based on the one link that still works, you might have also been trying to shoot at a slightly shorter distance than the roughly 46 inches Minimum Focus Distance of that lens.

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If memory serves me well, this otherwise excellent lens' weakest spot is 70mm at short focusing distance (and wide open) - at least it was the case with my copy. I'd suggest that you do more tests at different focal lengths and distances to get a bigger picture. Also try with IS on and off.

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