Do I have focus shift? (Image attached)

Started Feb 29, 2012 | Discussions
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ProtonPump Regular Member • Posts: 205
Do I have focus shift? (Image attached)

I attached my CV 35mm f/1.2 to a micro four thirds camera and did a quick focus shift test. I don't have any clue how to asses lens focus shift. Please note that I also have very bad eye sight. Someone else with a better eye would be best at telling me what I may not be seeing.

Setting: The barcode is on a paper receipt. The barcode is about 1.25 inches in length. The m4/3 camera was set about 0.5 meter from the barcode. I didn't have a tripod, but I did stabilize the camera as best as I could while I changed the aperture.

Testing done under my bedroom's light at 8PM.

My focus was at the number "4". I realized that as I stopped the lens down, the barcode to the right quickly became more in focused than the numbers on left. However, "4" is still sharp...

Does this lens have focus shift? If so, how bad?

Would the focus shift be worse/more noticeable if I had setup the testing any other way? ie. farther camera from subject, etc?

Irakly Shanidze
Irakly Shanidze Veteran Member • Posts: 5,258
Re: Do I have focus shift? (Image attached)

No, it seems that your lens is just fine. loss of sharpness after f/11 is due to diffraction. Whatever shift is there (if any) is offset by increase in the DOF
Irakly Shanidze

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