Autofocus adjustment testing target

Started Mar 4, 2013 | Discussions thread
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coronawithlime
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Autofocus adjustment testing target
Mar 4, 2013

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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Nikon D800
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