How to AF fine tune?

Started Jul 7, 2011 | Discussions thread
jamesm007
Veteran MemberPosts: 5,425Gear list
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Re: How to AF fine tune?
In reply to Twilight35, Jul 10, 2011

Twilight35 wrote:

Try this method. http://www.peleng8.com/how-to-detect-back-focus.html

Fred

IMO...

This method is flawed. The target is not centered with the scale. This will produce IMO readings that are FF or just plain wrong.

Also most people know there are cross phase detect sensors and ones that are only diagonal or horizontal. However the center is a cross phase detect sensor, so its two sensors! It can give different results in landscape or portrait holding. Its OK to just take landscape test and go with it, but it would not hurt to do a vertical test and average the results as shown below.

The below is from a modern dSLR service manual. I could be wrong but I just don't see even taking into account the chart says to go off of f/stop and some tolerance that it could be accurate enough to help.

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Pentax K20D Pentax K-5 Sigma 10-20mm F4-5.6 EX DC HSM Pentax smc DA 55-300mm F4.0-5.8 ED Sigma 17-70mm F2.8-4 DC Macro OS HSM +9 more
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