Re: Work-around for full-press AF error
Raist3d wrote:
Anders W wrote:
Raist3d wrote:
Anders W wrote:
Raist3d wrote:
Anders W wrote:
Raist3d wrote:
Anders W wrote:
Raist3d wrote:
Anders W wrote:
Raist3d wrote:
ahaslett wrote:
Anders W wrote:
ahaslett wrote:
Raist3d wrote:
Anders W wrote:
Raist3d wrote:
Anders W wrote:
Raist3d wrote:
Anders W wrote:
DKG wrote:
I have both versions of it and they are real workhorses for a compact setup. In my view sharper (or, at least, crisper) than the 17mm/1.8 but yes, painfully slow to focus, especially on Olympus bodies. Probably because of the latter, it doesn’t co-operate well with some Olympus bodies (those, I think, which don’t have the ability to switch on ‘focus-priority shooting’ - mainly the PEN Lite and the E-M10 lines) as the shutter seems to fire before focus is fully achieved. The workaround is to wait for focus confirmation with a half-press of the shutter release button… not ideal for fast-action where there may not be time to wait that extra fraction of a second.
Well, the 20/1.7 was not designed for AF-C and Panasonic bodies won’t even let it enter that mode. I think Oly bodies do but it’s not a good idea to try (e.g., for the reason you mention).
In AF-S mode, it is slow if you allow it to hunt (I don’t) or if you refocus from close-up to infinity or the reverse. But for my standard use case, where refocusing would be limited to the 0.75 meters to infinity range, it refocuses about as quickly as lenses with internal focus. And yes, I’ve tested that systematically (on an Oly body), using the Oly 12/2 and 45/1.8 as “competitors”.
As much as I liek the 20 mm F1.7- one outstanding issue on Oly bodies (any body I have tried). is that if you full press the shutter to get a shot, very often it will be out of focus. I find I have to half press, wait for focus, then finish- then it works.
Well, that hasn’t happened on any of the four Oly bodies I have used it with (E-M5.1, E-M1.1, PEN-F, and E-M1), provided I stay in the AF-S mode the lens is designed four. In pure AF-S mode, the camera simply won’t fire unless it has acquired focus. In AF-S with MF mode, it will eventually fire anyway but only after a long wait (several seconds)..
It looks like we have reached an impasse and can't agree.
I have used the EM5MKII, EM5MKIII, the Pen-F, the EP-7, the EM10MKIV, the EPL9. On every single one of them this behavior can be seen. And to be clear I am talking a bout AF-S.
" In pure AF-S mode, the camera simply won’t fire unless it has acquired focus."
Again, not for this Panasonic. Also I wouldn't say that's 100% for some other lenses but it's close to your observation that it should be near 100%. But for this 20mm F1.7 that's not the case for me.
I just tried this again with my PEN-F and the 20/1.7 (mark I) with the lens cap on to prevent it from acquiring focus. It simply won’t fire in pure AF-S mode. In AF-S+MF mode it will, although only if you wait for several seconds. Firmware is the latest available for both body and lens.
Same here for all my cameras. I have gotten false shots done on PenF with Oly 75mm but rate. That said with the 20mm -> try several real shots (no caps covering). Cap covering is a very obvious AF miss, so not surprised the Camera does better at refusing to lock focus vs other real world cases.
Please do the same test if you can. It would surprise me very much if you got a different result.
I did. And I have done this many times. Every single Olympus camera I get new I always try this lens to see if it's finally corrected.
I am sure what you describe can happen in AF-C mode though, especially if the camera isn’t set for focus priority.
All of the the cameras have been set for focus priority where they allow that option.
I wish Olympus/OMDS resolved this incompatibility. This doesn't happen on Lumix bodies.
In either case I still like the lens.
Full press
Half press -> instant AF lock confirmation -> Full press
You learn something new every day!
Andrew
Yeah. I have managed to reproduce the problem now too. While the camera doesn’t fire in pure AF-S when it’s obvious that it hasn’t acquired focus, it does sometimes fire without actually having acquired focus if you full-press. I wasn’t aware of this until now since I hardly ever shoot without pre-focusing with a half-press.
Hard to understand what the cause of this problem is, particularly since AF works as it should on half-press.
Maybe the lens accepts a PDAF command and the Olympus firmware assumes it has time to move before actuating the shutter.
thats not it this happens on CDAF or not cameras too
Without knowing a lot of detail about Olympus hybrid AF, the MFT standard and the 20mm AF hardware and firmware, it’s hard to say.
I jonsslty don’t understand either why this lens has a problem maybe something Panasonic is not letting on but I would have imagined that wouldn’t be impossible to reverse engineer
but you know - it’s supposed to be the m43 standard
Andrew
Only workaround I’ve found so far is to half-press and then full-press the instant you hear the focus motor stop or see focus confirmed in/on the EVF/LCD. Not that you should have to do this but at least the delay until shutter opens is very nearly the same as with a direct full-press.
Well that’s what I said you ha e to do to make it work what you describe is the shortest way to do it. I would ah e preferred if it could focus on full press as sometimes I can pan and track a bit with Panasonic on a full shutter press
OK. As I indicated, we would all prefer that it would work with a direct full-press too and Olympus should definitely have fixed this long ago. Just wanted to mention what the work-around for now is. And as to panning and tracking, it should be just as easy to do with a half-press followed by full press on focus acquisition as with a just a direct full-press.
No, it's not as easy to do because you have to deal with the small delay however small. At least for some of the stuff I shoot. You can get away with some of it.
What I mean is that in both cases you can follow (pan) the subject in the frame until the instant the shutter opens. No difference in that regard.
The difference is the human delay between having to wait for AF then press full vs pressing in full. There IS a difference.
I mean, what you cited is the best way to work with this, sure, though I think it's a bit straightforward to conclude once you realize the steps you have to do. I don't have focus acquired sound on, on my camera.
Neither do I. But the lens makes noise when it focuses and to the extent that I can hear it, I'd just full-press the instant it stops. If I can't hear it because the surroundings are too noise, I watch the focus acquisition indicator in/on the EVF/LCD.
Yes, but my point is, you still have the human lag in. Depending on the shot, that may be enough of a delay or not.
Sure. The total delay will be longer with the work-around. My point is that if you're sufficiently attentive, the difference is small.
And my point is that that human reaction lag is enough to miss a shot sometimes or often depending on what you are doing. In either case this is not a fast focusing lens.
Sure. That additional delay might of course be critical in some instances. All I am saying is that the extra delay is small relative to the time it takes for the lens to AF. Had the lens been able to AF faster, the extra delay would have accounted for a greater portion of the total delay.
Well ok but that's straightforwardly clinical :-). My point is that it doesn't matter how much small it is than the full AF, the issue of the human lag enough to miss some shots is still there.
The AF process takes about half a second no matter how you do it. The additional delay from the instant focus has been acquired to the instant I when I full-press the shutter button is much shorter than that.
But again, that's not the issue I am talking about. The issue is if you are doing any tracking or panning your an't just do a full press. The small delay you talk about while compared to the full AF is "short"- is enough to throw off some shots.
I have a hard time understanding your reasoning when it comes to tracking/panning.
I am merely describing one scenario this lens has a harder time on OMDS cameras.
Irrespective of whether you shoot with a direct full-press or a half-press followed by a full-press when focus has been acquired, you can keep tracking/panning the subject in/on the EVF/LCD until the shutter actually opens.
The issue is you can do some of that, but if the human lag on the shot stops you from the object move in such a way that now it's slightly out of focus, then you will face that problem. It certainly depends. One case would be say a cyclist you are tracking that at the moment your camera locked focus he decides to come closer or further away from you.
OK. I understand what you mean now. The difference between the focus distance set by AF and the actual subject distance when the shutter opens might become larger due to the extra delay. I thought you just meant panning/tracking the subject from the side to keep it framed the way you want and/or create a sense of motion by blurring the background through panning.
It really depends on what you are shooting.
So there’s no special disadvantage in that regard.
I am sorry but I still see it for some cases. This wouldn't happen if you could simply full press AF.
With the work-around, you just have to keep tracking/panning for a short instant longer than you would with a direct full-press.
As I said, depends on what you are shooting. That human lag is enough to miss focus in some situations. Certainly not all.
To me this isn't really a work around because the issue is still there - you aren't really avoiding it. And the conclusion that doing this will reduce full shot time to take seems rather straight forward- it's the same with any lens.
