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04-17-2017, 03:04 PM   #1
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Testing auto focus accuracy with manual lenses.

So I've determined my new K-1 and DFA 24-70 have a back focus issue. I'm getting the best results at +10 AF adjustment (which imo is beyond accectable tolarences. Hopefully B&H or Ricoh will agree)so I'm thinking either the lens, the body or both have a calibration issue or somthing worse. Before I attempt an exchange I'd like to isolate the issue to either the lens or the body. I don't have access to another AF lens but I do have a manual 50mm 1.4. My question is could a manual lens along with the cameras in focus indicator be used as a guide to determine if there is a AF problem with the body?

04-17-2017, 03:32 PM   #2
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Yes do the same tests with the manual lens.

As I understand it the -10/+10 adjustment range represents the maximum manufacturing tolerances of the camera. So if you need to use +10 that is within tolerance. I have to use somewhere between +6 to +10 on all my lenses with the K1
04-17-2017, 03:39 PM   #3
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The good news is that AF adjustments are a part of life these days, rather than a defect in the gear, so don't panic just yet

AF adjustments are meant for AF lenses only, so shouldn't use manual lenses if you want to reliably determine global AF adjustments. But you could certainly try catch in focus and see if the photos are usable- this would be a decent indicator that your camera is OK. However, since manual lens AF confirmation has a large tolerance range, a better solution would be to pick up a very cheap AF lens, like the DA L 18-55mm, for testing.

If +10 is yielding sharp photos across the board with the 24-70mm, no further action should be needed as long as the other lens doesn't also need a +10.

Otherwise, I'd recommend sending the combo in for calibration. Precision should be able to figure out to what degree the body/lens is at fault, and apply further corrections if/as needed.

Adam
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