I have been laid up in a chair looking out at my garden for the past week and have been doing a good deal of testing on OM-1 focus.I have previously reported that S-AF has excellent discrimination when trying to select a bird in a bush, instead of the branches.  That is still true.  It is almost 100% accurate in picking the bird using single AF area.However now I have found a problem.My chair is 4 metres from some plants, some of which have tall leafy twigs.  Behind the plants is a gap of 150 meters (the land drops away) to a bank of trees on the opposite side of an inlet.If I focus using S-AF on the distant trees and then aim the camera at the plants, the plants are so out of focus that there is only a vague blur before focusing.  Pressing half shutter does nothing, no focus change but focus confirmation square in the centre of the AF areaI does not happen every time, and is worse for small subjectsIf a bird landed on the plants I would definitely miss focus on it.If I change to C-AF things are much better, usually after a bit of trying the camera gets focus.Settings are S, 1/1250, iso auto, AF scanner on, AF area single, (same with other AF area sizes)Lens PL50-200 +1.4x (its the same without the TC)So it looks as though S-AF is best for the specific task of picking out a bird in a bush (and I could set that up as my C1 setting, and C-AF for everything else with C2 for normal perched birds and C3 for BIF.If anyone is still reading DPR, any suggestions?

Maybe check out this thread:https://www.dpreview.com/forums/post/66979845Apparently there is no issue.

I have a dirty window 10 ft away  with trees at 50 ft and a hillside at 1/4 mile. In S-AF if I initially focus on furniture maybe 3 ft away, the camera focuses fine. If I move the focus point (smallest box) to aim at the window, if focuses fine. If I move to the trees or hillside it focuses fine but if I then move the focus box back to the dirty window the camera will ignore the dirty window and look for a target beyond the window. I think this is due to the contrast detect S-AF moving the focus short distances in both directions looking for target at about the same distance as it's last focus lock distance. If it can't find any  target at the far distance than it may eventually change the focus distance to over a wide enough range to now detect the dirty window.It's sort of like using a lens with a focus limiter switch set to far instead of near.I would suggest using the manual focus touch up (S-AF+MF) to jump the focus distance back to your near subject.Dick

Pete_W wrote:Maybe check out this thread:https://www.dpreview.com/forums/post/66979845Apparently there is no issue.I am not sure how to take your comment, whether it is serous or sarcastic?I did contribute to that thread and at the time had not reliably encountered the problem.  As a result of a lot of testing I can say that it does exist with my current setup and lens.  I can try it with a different lens (or two) to see if the lens is the problem.  Unfortunately apart from my 75-300 all my long lenses are Panasonic so I may not be giving the system a fair chance.It would be helpful if anyone could reproduce this test and come up with perfect focusing behaviour.  If they can I would send the camera in for checking but I am loath to be without it.Thankstom

If I get a vote . . .It reads like mocking sarcasm to me, particularly since he explicitly linked to your post in that previous thread.And I don't like it much.

Digital Dick wrote:I have a dirty window 10 ft away with trees at 50 ft and a hillside at 1/4 mile. In S-AF if I initially focus on furniture maybe 3 ft away, the camera focuses fine. If I move the focus point (smallest box) to aim at the window, if focuses fine. If I move to the trees or hillside it focuses fine but if I then move the focus box back to the dirty window the camera will ignore the dirty window and look for a target beyond the window. I think this is due to the contrast detect S-AF moving the focus short distances in both directions looking for target at about the same distance as it's last focus lock distance. If it can't find any target at the far distance than it may eventually change the focus distance to over a wide enough range to now detect the dirty window.It's sort of like using a lens with a focus limiter switch set to far instead of near.I would suggest using the manual focus touch up (S-AF+MF) to jump the focus distance back to your near subject.DickDickThanks, that is indeed the same problem.  Thanks also for the suggestion about using S-AF+MF.  I am sure that would work but it might slow the shooting process up too much.I think it is distance as well as contrast/light related.  The problem really only shows up if the camera has racked focus out to a long distance and it is being asked to refocus to something much closer.  One quick if dirty work around would be a quick half press at something only 50m away before aiming at the close subject.More testing needed (also with other lenses)tom

I am not sure if you have already seen these two recent videos from Thomas Eisl about how OM-1 autofocus is designed and how to achieve focus in different scenarios.Maybe they will help at least explaining why the autofocus behaves like this if not offering a solution to the problem.https://youtu.be/qo9xAAjOffAhttps://youtu.be/XRriqq4PRhk

The OM1 SAF is definitely different from the E-M1s.  SAF on the EM1s was hybrid focus where it initially focused like CAF (using PDAF) and then completed focus using CDAF.The OM1 does not appear to be using PDAF for initial focus in SAF mode.  It appears to be using only CDAF.  I have noticed that it focuses well in SAF mode, as long as the somewhat target is visible in the EVF, but it can have problems if the target is completely out of focus especially if the target has low contrast.  This is more likely to be a problem with longer telephoto lenses.This hasn't been a problem for me since I always pre-focus for expected target distances with the snap ring or by zone focus.  If things are likely to move, then I use CAF, if they are stationary with twigs/branches, then I switch to SAF and single point focus.

inlight wrote:I am not sure if you have already seen these two recent videos from Thomas Eisl about how OM-1 autofocus is designed and how to achieve focus in different scenarios.Maybe they will help at least explaining why the autofocus behaves like this if not offering a solution to the problem.https://youtu.be/qo9xAAjOffAhttps://youtu.be/XRriqq4PRhkThank you.  I saw these some time ago, but have just reviewed them again.  As you say, they don't actually solve the problem, but are really good stuffTom

tomhongkong wrote:Pete_W wrote:Maybe check out this thread:https://www.dpreview.com/forums/post/66979845Apparently there is no issue.I am not sure how to take your comment, whether it is serous or sarcastic?Most definitely the latter.I'd just read that other thread and was a bit taken aback by this comment:"The OP has gone quiet.....he's probably found out what he was doing wrong and doesn't want to admit it."To be fair, that kind of response happens frequently in this forum, i.e. any perceived criticism of OM gear results in defensive comments implying the poster doesn't know what they're doing.

Caledonia wrote:If I get a vote . . .It reads like mocking sarcasm to me, particularly since he explicitly linked to your post in that previous thread.And I don't like it much.I replied as though it was meant seriously and hope it was.  Like many I am here to learn.  I am always rather sorry for people who try to score points and be clever on the forum at the expense of others (only a week to go!)thanks for the commenttom

tomhongkong wrote:Digital Dick wrote:I have a dirty window 10 ft away with trees at 50 ft and a hillside at 1/4 mile. In S-AF if I initially focus on furniture maybe 3 ft away, the camera focuses fine. If I move the focus point (smallest box) to aim at the window, if focuses fine. If I move to the trees or hillside it focuses fine but if I then move the focus box back to the dirty window the camera will ignore the dirty window and look for a target beyond the window. I think this is due to the contrast detect S-AF moving the focus short distances in both directions looking for target at about the same distance as it's last focus lock distance. If it can't find any target at the far distance than it may eventually change the focus distance to over a wide enough range to now detect the dirty window.It's sort of like using a lens with a focus limiter switch set to far instead of near.I would suggest using the manual focus touch up (S-AF+MF) to jump the focus distance back to your near subject.DickDickThanks, that is indeed the same problem. Thanks also for the suggestion about using S-AF+MF. I am sure that would work but it might slow the shooting process up too much.I think it is distance as well as contrast/light related. The problem really only shows up if the camera has racked focus out to a long distance and it is being asked to refocus to something much closer. One quick if dirty work around would be a quick half press at something only 50m away before aiming at the close subject.More testing needed (also with other lenses)tomIn the field I generally only use CAF but I usually reset focus to my main focus zone of the moment whenever I have focussed out to a long distance for a long range photo. So I sort of do that automatically, just not using SAF.Another way is to use the soft focus limiter in the camera to a short, long and off range.

While I am generally pleased with my OM-1s' AF performance, I have found this issue, and similar ones to what others describe, every so often.  I now allow manual override in all my custom settings, so if a situation like the one you describe happens, Tom, I'll re-focus manually on the bush if that speeds up the process.Not ideal, and I hope it will be remedied with future firmware updates, but I can live with it.LotharP.S.:  See you on DPRevived.com?  It more and more looks like the closest replacement to DPReview.