Sharpness quality changes with object's distance

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shadyyx
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Sharpness quality changes with object's distance
3 months ago

I used to think there is something wrong with my setup (Canon EOS 70D and EF 100-400mm L IS USM lens) since 70% of images were too soft or blurry but after reading of book "Bird photography" I have found out that I am just using too slow shutter speed (especially since I am shooting handheld only). After going for faster shutter speeds (1/1000 and more) I am getting much better results. The backdraw is I often need to go also for higher ISO and what seemed to be a no problem for this camera (400-1200) I can often found as quite sensible amount of noise when zooming to 100% of image size (!).

The problem I am experiencing is very poor IQ when shooting objects far away (e.g. more then 50m (164 feet) away). For better imagination:

  • I had an opportunity to shoot egrets and herons from about 5m (16.5 feet) and the results are quite fine (yet I can imagine them to be extremely satisfying when shot using FF) - lot of details, sharpness is satisfying, colors are very accurate though the ISO 400-800 produced quite a lot of grain.
  • Then usually I shoot objects from 5-50m (16-164 feet) and though there is significant "softness" in the images I still can say they are quite good (especially when less then 20m (65 feet).
  • Finally when shooting objects that are more then 20m (65 feet) and farther the IQ drops rapidly. It is not the problem they are not focused at - e.g. I was shooting great cormorants sitting on a wooden pikes sticking out from the water thus there shouldn't be a problem to focus on black objects in front of light blue background. Anyway I tried few shots with different aperture settings (yes I tried even f/20) to change the DoF to no avail. Each shot contained only a completely blurry/soft cormorants. It was possible to identify them because of the basic body shape with wings wide open to dry out after fishing but that was all the "detail". The trees behind the lake looked very distorted as well.

Now I do not know whether each lens (each focal length) should be used at some distance only or whether if I focus on 200m (656 feet) distant object it should be still tick-sharp. Or is it because of the body or focusing system itself?

Thanks for the replies.

 shadyyx's gear list:shadyyx's gear list
Canon EOS 70D Canon EF 100-400mm f/4.5-5.6L IS USM Canon EF-S 18-135mm f/3.5-5.6 IS STM
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