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Canon 50D Defraction Test (20081024)

I preformed this experiment, as the rumours were that the pixel density on the Canon 50D would be taxing the lens' resolution, and there would be noticeable image degradation above f-8 due to defraction.

The linked files are all 1:1 crops shot with my 24-70L with a 25 mm tube on my 50D, and saved as "Medium-fine". At f-22, there is definitely defraction blurring, but it isn't that noticeable at f-18. A big bonus for the first person to recognise the image! {:-) It's pretty common.

Select image thumbnail for large WWW version


f-stop (600x500 67KB)
f-stop 3.5 (600x500 73KB)
f-stop 4.5 (600x500 77KB)
f-stop 5.6 (600x500 77KB)
f-stop 7.1 (600x500 76KB)

f-stop 9 (600x500 83KB)
f-stop 11 (600x500 81KB)
f-stop 14 (600x500 81KB)
f-stop 18 (600x500 78KB)
f-stop 22 (600x500 71KB)

This second set are all 256 x 256 pixel 1:1 crops, without any linked files, shot with my 200 2.8L with a 25 mm extension tube on my 50D, and saved as "Large-fine"

Essentially, from 4.5 to 14 posses similar clarity. It doesn't appear that defraction is a noticeable concern


f-stop 2.8 (256x256 26KB)
f-stop 3.5 (256x256 26KB)
f-stop 4.5 (256x256 26KB)
f-stop 5.6 (256x256 26KB)
f-stop 7.1 (256x256 26KB)

f-stop 9 (256x256 26KB)
f-stop 11 (256x256 26KB)
f-stop 14 (256x256 26KB)
f-stop 18 (256x256 26KB)
f-stop 22 (256x256 26KB)
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