Autofocus adjustment testing target

Started Mar 4, 2013 | Discussions thread
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(unknown member) Veteran Member • Posts: 3,985
Autofocus adjustment testing target

Presented entirely without comment.  I'm only relating what I THINK I observed.    If somebody wants to point out an error in this I would be grateful, because there is almost certainly some pilot error in here somewhere.

I decided to do some lens AF adjustment retesting today.  Bright sun.  No Wind.  Tripod.  Mirror up.  AF-S.  Wide open and 1/6000.  Regular stuff.  Used a Nikon 60mm f2.8 macro and a Nikon 28-70 f2.8 @ 70mm, both on a D800.  On a whim I decided to use the FoCal target outside.  Printed three of them and lined them up on a wall.  Noticed that my lenses would not focus on the target.  Live View focused ok, but using the viewfinder was a no-go.

Tried the Lens Align device and got better results, but still seemed to be a bit sluggish.  I guess that's too relative to quantify, but that seems to be the best way to describe my subjective impression.

On a whim, I downloaded and printed out one of the targets that are said to be similar to what Nikon shows in their service manual and uses in their shop.  Looked a lot like the one Thom Hogan has in his article on FA testing.

I trimmed the target and glued it on the Lens Align device in place of the oem target.

The focus operation seemed MUCH crisper and I got more consistent results.  I also got results closer to 0 AF fine tune than I had previously gotten.

I'm interpreting this to mean that my previous testing was faulty due to inconsistent focusing on a more difficult target.  Which is kinda distressing, because I had convinced myself that I did a pretty good job the first time around, but I believe I was mistaken.  

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One day long ago, a sorcerer and a warrior did battle, as such things were commonplace in that age. Sometimes the sorcerer won, and the sum value of human abilities was improved some trifling amount. Sometimes the warrior won, and again the human race improved by some insignificant amount, for a sorcerer who can't defeat one miserable warrior is a poor sorcerer indeed.

Nikon D800
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