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Old 04-01-2013, 06:03 PM
Jorda75078 Jorda75078 is offline
Larry Jordan
 
Join Date: Apr 2011
Location: Inverness, FL
Posts: 17
Default Is it the lens or camera body that demands AF fine tuning?

While doing AF fine tuning (micro adjustment) last summer, I discovered a pattern. Actually, I discovered two patterns. I found that the AF fine tuning required for a specific lens would be an indication of what the fine tuning would be on another camera body, but I could not skip the fine tuning process because the camera body could also influence the final setting.

The attached table shows you the AF fine tuning settings that were required for all of my lenses on all three of my camera bodies. For all but one lens, the adjustment was positive which means the lenses were front focusing…or focusing closer to the camera than indicated in the viewfinder. However, the amount of the adjustment was not always the same from camera body to camera body.

If you study the table for a minute you will see the patterns that I saw. The settings for the D800 and the first D800e are pretty close to the same. In other words, it was the lens that was causing the AF fine tuning to be off (not result in a zero adjustment). The one exception to that pattern was for the 200-400mm lens with a teleconverter (TC) installed. I had a lot of difficulty getting a final adjustment with this lens and the 1.4x TC installed, and I subsequently do not use it very much because I don’t trust the combination.

Now look at the last column and compare it with the first column. For several of the lens, the adjustment is about 5 points less for the D800e than the D800 but the numbers follow the same pattern as the first two columns. This implies that it is also the camera mount that is causing the AF to shift and have to be adjusted. The exceptions to this pattern are the 70-200mm lens with the TC installed and the 200-400mm lens settings. These two sets of number show you why you cannot simply assume a pattern based on tests with two camera bodies and apply those same settings with another body. You have to tests every lens with every camera body.

(I will discuss the +20 that I got with the 70-200mm and TC and how I live with it in another posting.)
Attached Files
File Type: pdf AF Settings Table.pdf (12.3 KB, 2 views)
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Larry Jordan

www.larryjordan.smugmug.com
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