D7100 AF Fine Tune VS. Sigma 18-35 USB Dock Problem

Started Mar 4, 2014 | Discussions thread
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chary zp Senior Member • Posts: 1,452
D7100 AF Fine Tune VS. Sigma 18-35 USB Dock Problem

Now, my D7100 is not the best friend with my lenses if I turn AF Fine Tune (FT) off. My eight lenses currently vary from -10 to +8 and only one works fine with FT:0. But after FT they perform great. So fine then.

Now Sigma 18-35/1,8.

I did some measurement at given focusing distances, as the dock programme can set custom values from -20 to +20 at 0,28 m 0,35 m 0,5ish m and infinity.

First, -10 in D7100's FT does not correspond to -10 in the dock software. But I tried hard and tuned the lens to the best possible outcome for focusing at 3-8 meters, as I knew I was going to need the lens to focus at those distances. Quite a lot of fiddling and it performed quite well, if it had something to catch the focus on. It was a concert-like event with changeable lighting and not good one at that, but I did choose some nice and sharp images in the end. I'll show some of them in a comprehensive D7100 + 18-35/1,8 + 85/1,8g + 50/1,8d "review".

Now I tried the lens again, trying to focus at about 15 meters, 4 meters and infinity-ish (about 500-700 meters) and the AF was absolutely off. On saturday it was OK, today it was a vat of $%^&.

Liike, on Friday I set it to work at FT-0 and now I need something from -2 to -20 and various values in the matrix, these are FT values to be set in camera:

18mm: -4 -6 -8 -2

24mm: -12 -9 -12 -8

28mm: -6 -6 -7 -2

35mm: -6 -4 -20! -16

The infinity values are actually tuned for focusing at about three meters. When I tried focusing at about 15 meters, I needed 18mm: -14 24-35mm: -12

Yesterday when I tried some really long distances, like two kilometers with good light and quite clean air I needed 18mm: -16 and 24-35mm: -14 for infinity focus.

MF via zoomed works LV great and the lens is so sharp I had to get some plasters while trying it out. But AF makes it impossible to shoot action or brings a ton of waste.

Any ideas why the AF got so un-tuned after two days? The other lenses still perform great, so I'd rule any voodoo in the camera out. It almost seems as if I needed to FT every single time I took the camera out of the bag and differently for different focal lengths and focusing distances.

Is the AF in the lens really so horrible or am I cursed?

 chary zp's gear list:chary zp's gear list
Nikon D90 Nikon D200 Nikon D7100 Nikon D500 Nikon AF-S DX Nikkor 18-105mm f/3.5-5.6G ED VR +11 more
Nikon D7100
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