How much AF fine tune does your D800 need?

Started Jun 24, 2012 | Discussions thread
itcrashed
Regular MemberPosts: 144Gear list
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Re: How much AF fine tune does your D800 need?
In reply to GMack, Jul 11, 2012

Now that you've done that work, try putting on a Nikon SB flash with the Auto-focus assist light in it turned ON and see what happens with your tuning numbers. Just learned today that my SB-900 requires me to set a -20 in it if I use the SB flash and it uses its red internal AF assist light indoors with two zooms. Someone mentioned it was a known defect in the Nikon flash. I shut if off, then the AF tuning is fine if I use more light or assist the body with a strong LED flashlight pointed on what the AF sensor is looking at. Maybe something to do with why the Nikon body uses white assist light and the strobe uses red, although the one in the body is worthless since most large diameter fast lenses block it hitting the center AF target in the viewfinder.

Aaaarrrrrgggg! I threw on my SB-910 and did some really simple tests and I'm finding that it backfocuses quite a bit when I use the AF assist light on the SB-910. And just like you experienced, when I turn the assist light off, it focuses just fine.

Next try your new AF tuning numbers above over the zoom range of your zooms and not just the midpoint focal length. Mine deviate from wide, mid, and tele in the AF tuning numbers I get from using FoCal. I carry a "Lens AF Tuning Chart" with me now. I need to add the flash's assist light and back-focus thing too.

Yah I'm familiar with the problem with tuning zooms. You have to pick the focal length that matters most to you and calibrate it from there. I just did mid focal length to make sure Nikon repaired my AF issues properly, and I also used it as a basis of comparison against the adjustments needed prior to the repair.

...but back to the AF assist light inaccuracy. It sounds like I'm going to continue to spend countless hours on this site to see if, how, and when a solution comes. Fortunately I hardly use my speedlight and if I do, it's hardly ever on the hot shoe as I use manual adjustments using CLS.

I swear I think I have more clicks on my D800 from testing rather than real shooting.

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Fujifilm X-T1 Nikon D4s Nikon AF-S Nikkor 14-24mm f/2.8G ED Nikon AF-S Nikkor 24-70mm f/2.8G ED Nikon AF-S Nikkor 50mm f/1.4G +5 more
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