DotTune: Video Tutorial for AF tuning without photographs

Started Feb 18, 2013 | Discussions thread
clarnibass Senior Member • Posts: 2,044
Re: DotTune: Video Tutorial for AF tuning without photographs

OK, I tried again and used your target (which someone has claimed to be unreliable, a bit more on that later).

This time I tested my 50mm lens. I manual focused and auto focused using Live View (LV) a few times to make sure LV is focusing correctly. It was excellent and completley consistent. I found I sometimes had to wait more than 5 seconds, for example it would flicker after 6 or 7 seconds, for example. It stopped flickering for at least 10 seconds at -17 and +15, with +16 being very hard to verify, I got it to flicker once but could also get it to stay for at least 10 seconds.

So conlcusion is either -1 or 0 should be right. I know this lens has focus shift. Slight back focus at f/1.8 and then gets to a slight front focus around f/2.8, where in general with DOF being bigger it's not a real problem IME. I could see the focus shift using a 3D target.

I tested at f/1.8 so it is a little strange that if anything, it's supposed to be -1 if not 0. I'm not sure why that is. Anyway, since +16 was so solid, I'm keeping FT Off anyway since I haven't yet found a lens that really needed it (some apertures might benefit from it just slightly, but overall no FT works better).

I am guessing the 3D target, eventhough the focus point was completely inside a flat surface (by a significant amount), confused the camera... or not.

Re the target, I used relatively decent but not particularly good conditions. I could not make the outer focus points not focus on this target, let alone the center one. The outer and center points just consistently focused on the target.

Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow