Softness on the edge

Started Feb 22, 2021 | Questions thread
TrackDayLT4 Regular Member • Posts: 143
Re: Softness on the edge
3

Kendunn wrote:

MitchAlsup wrote:

Kendunn wrote:

Getting a weird, overly soft edge on rare occasions, not sure whats up. Canon 5DS with a 17-40. The example posted shows the top 20% of the frame is way too soft, but the rest of the frame is reasonably sharp, including the bottom. It was shot at 35mm, f/7.1 off of a tripod, I think it was 1/20 at ISO 100. Most of the time images are fine. Loose element?

You do realize the stuff at the top is more than twice as far away as where the tree emerges from the ground !! do you not ?

My guess is that the lens accommodation (near-focus to far-focus) is the culprit. Your choices are to push the aperture slower and get diffraction across the whole image or to widen the aperture and deliberately take the top OoF.

Thanks for the input, but a 35mm len @ 7.1 focused at 20' will have a DOF to infinity. This tree was probably 100' away and what was focused on. You can also look close at right side of the image and see trees that are sharp at their base but very soft at the top.

You have to state the assumptions for DOF calculations and the COC.   Your statement may be true for an 8x10 print viewed at 10", but not for pixel peeping a 50mp full frame sensor at 100%.

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