X100V unreliable autofocus and possible cause

Started 4 months ago | Discussions thread
Alessandro63 Contributing Member • Posts: 879
AF mistery

Just for your information: I went hiking yesterday, and with your method (MF+AFL) I got plenty of crisp images (all of them, actually) instead of the usual percentage of slightly misfocused ones.
This odd behaviour (AF with stepped down aperture) has already been negated by some dpr frequenters. Happened the same some time ago, when I brought the matter to the attention. No one took me seriously. But I'm sure it works that way, as you found out. I tried many times with different bodies and lenses.
Of course, DOF is allowing for correctly focused images; but there are occasional failures, which I find more frequent in landscape "casual" photography, as I do during my hikes.
Why it works that way remains a mistery for me. If it can focus at full aperture and show the correct exposure in EVF/screen using MF+AFL, why not doing the same with AF?
If anyone care to verify and guess a reason for it, I'd be glad to ear. My worst guesses: a trick to speed up focusing, gone bad; or a solution (gone bad) for the initial problems of aperture chattering.
A recap: in good light, with aperture stepped down (aperture priority), in AF, try to focus and refocus on anything, looking into the front of the lens. You should see that most of the times the aperture will not fully open up. For comparison, do the same in MF using the AFL button to focus: you should see that the aperture stays fully open.

Why it could be a problem: quite obviously, given the DOF with a stepped down aperture, there's a range of focusing distances to choose among. The problem with landscape is that DOF at a distance is deeper, and sometimes the camera choses a slightly off one, and you end up with a less than crisp horizon, for instance (far mountains and such).
Seriously: for me it stopped happening yesterday, after having learned the MF+AFL solution, which is going to become my preferred focusing method.

Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow