My current method to determine AF-Fine Adjust values

Started Mar 26, 2013 | Discussions thread
emem Veteran Member • Posts: 4,216
Re: My current method to determine AF-Fine Adjust values

awaldram wrote:

IMO you should always calibrate at the widest aperture and focal creep will be compensated by the increase DoF at smaller aperture.

The mistake most people make when attempting to calibrate their lens is they don't' bother/realize that that peak sharpness for a lens will not be 50-50 within the DoF but will vary depending on focal length and aperture.

Some example to show just how far people are miss-calibrating their equipment if they do not look up the correct peak placement in the DoF

16mm @f2.8 10ft target 17% in front 83% behind

16mm @f4 10ft target 3% in-front 97% behind

50mm @f2.8 10ft target 47% in-front 53% behind

Without this knowledge its impossible to calibrate a lens correctly whatever tool you use and IMO leads to many people thinking they have faulty equipment.

Hence why I'm so cynical when you see 'everyone of my lens requires calibration'

For the average shooter not willing to read up on the subject its safer to let be than fiddle without sufficient information to complete the job correctly.

Very interesting Andrew - I've looked up the DOFMaster website which provides exactly those numbers which you have mentioned. So what would the effect be if I fine tune my lens to FF, say, by 10 feet or BF by 10 feet?

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Mike McEnaney. (emem)

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