After reading your e-book "Secrets To The Nikon Autofocus System-Mirrorless Edition", I purchased FoCal to best tweak AF on my 600 AFS II with my D850. Prior to FoCal, I used an old USAF resolution chart to calibrate AF fine tuning at f/4 obtaining a value of -6 as seen here:
Using the FoCal AF calibration, it suggested +2 as the best value as seen here:
As you suggested it's best to check the settings and attached are my results. Picking the SKU labels on the transformer as my viewfinder's central sensor subject, the USAF chart gives me a better result when focused on the labels where the numbers and SKU lines are better focused at the -6 setting. If you look at the wooden pole supporting the transformer, the + 2 setting is better focused as expected because it is behind the transformer. My question is this, do I use the +2 setting or the -6? I didn't know if results from linear resolution in a USAF chart is equivalent to the sharpness needed in shooting the eye of birds or wildlife for tack sharp results. The sharpness difference between the -6 and +2 is a little more noticeable on my computer with LR that what I posted here.
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Using the FoCal AF calibration, it suggested +2 as the best value as seen here:
You can only see EXIF info for this image if you are logged in.
As you suggested it's best to check the settings and attached are my results. Picking the SKU labels on the transformer as my viewfinder's central sensor subject, the USAF chart gives me a better result when focused on the labels where the numbers and SKU lines are better focused at the -6 setting. If you look at the wooden pole supporting the transformer, the + 2 setting is better focused as expected because it is behind the transformer. My question is this, do I use the +2 setting or the -6? I didn't know if results from linear resolution in a USAF chart is equivalent to the sharpness needed in shooting the eye of birds or wildlife for tack sharp results. The sharpness difference between the -6 and +2 is a little more noticeable on my computer with LR that what I posted here.
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