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Archive 2012 · OM-D out of focus infrequently.
  
 
WillWeb
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p.2 #1 · p.2 #1 · OM-D out of focus infrequently.


My OM-D is on the kitchen table laughing at me - I'm not allowed to play with it until Christmas.

One thing I don't understand about the focus problem: If I understand correctly, it occurs with the 12mm f/2 at distances over 5m. I checked a couple of online DOF calculators, and hyperfocal distance for 12mm f/2 on 4/3 is a touch over 4.5m, so in low light at >5m why not just set MF a hair short of infinity and forget about AF? Since I've only ever shot APS-C and -H (and once upon a time film), there may be something I'm missing here...



Dec 01, 2012 at 07:42 PM
Jonas B
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p.2 #2 · p.2 #2 · OM-D out of focus infrequently.


What we have this far is one report (from Makten) telling us about a problem. As the E-M5 has been available since April and the 12/2 for several months we should have seen numerous reports about the problem if it had been common. I have the same combination and never noticed anything (and my quick test above also didn't reveal anything).

If anyone want to focus using the hyperfocal method and estimated shooting distances or want to take more control over the exact focus plane is a personal thing. I usually focus manually using the viewfinder in enlarged view if not in a hurry. YMMV.

The only thing you've missed this far is the lack of reports about the problem. There may be something with some cameras or lenses. We don't know and as I see it there is no reason to worry.




Dec 01, 2012 at 08:15 PM
Makten
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p.2 #3 · p.2 #3 · OM-D out of focus infrequently.


Jonas B wrote:
I understand what you mean. Now I don't think 3 seconds at ISO 200 and 1/4 or so at at ISO 1600 is very different, and especially not so at 5meters.


I was refering to your second test, which was with better light, right?

The Zuiko 12/2 is a weird animal. You can focus it just fine manually if you avoid switching to the scale letting the focus ring stay in the AF position. Then there are no discrete steps but the lens instead acts as any other AF lens. Try it.

I certainly will! I had no idea that MF worked at all with the ring in its normal position.

I hear you about the green light signal though. There is obviously something Olympus should have done better. In the end I also understand it as you sell the camera mainly for other reasons. I see the 12/2 as a good lens (optically) but a nice try only (mechanics) to make a hybrid focusing lens. That lens itself will never be a reason for me to sell the camera though.

I like the lens when it does what it should and this problem is most likely due to the camera, since I can get it with the 20/1.7 as well. My other reasons are poor color (from the camera) and that I want shallower DOF, and I want one camera to do it all for me.

WillWeb wrote:
One thing I don't understand about the focus problem: If I understand correctly, it occurs with the 12mm f/2 at distances over 5m.


It also occurs with the 20/1.7 and at various distances. But it seems that it happens more often at larger distances than say ~3 meters. So, this is not something connected to the 12/2.0.

I checked a couple of online DOF calculators, and hyperfocal distance for 12mm f/2 on 4/3 is a touch over 4.5m, so in low light at >5m why not just set MF a hair short of infinity and forget about AF? Since I've only ever shot APS-C and -H (and once upon a time film), there may be something I'm missing here...

#1: Hyperfocal distance calculators are mostly nonsense, since they don't take account for viewing distance, resolution or anything. It's better just to look at some real images and develop a feeling for what aperture you need.

#2: Yes, MF probably works fine if it is like Jonas said, but I didn't know that until now. When you pull the focus ring for MF, you only have like 3 or 4 discrete distances to choose from, and they are all terribly wrong compared to what the scale says.



Dec 01, 2012 at 08:18 PM
 

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Makten
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p.2 #4 · p.2 #4 · OM-D out of focus infrequently.


Jonas B wrote:
What we have this far is one report (from Makten) telling us about a problem.


Umm, I didn't start the thread.

Edit: I seem to always find problems that no one else encounters. There are several explanations, and the two major ones would be that I'm very, very picky and that I don't use cameras like most other photographers do. I almost never shoot anything closer than 2 meters away for example, and 9 out of 10 lens test reports are dead wrong compared to what I see in my own images because of that.



Dec 01, 2012 at 08:19 PM
Jonas B
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p.2 #5 · p.2 #5 · OM-D out of focus infrequently.


Makten wrote:
I was refering to your second test, which was with better light, right?

I certainly will! I had no idea that MF worked at all with the ring in its normal position.

I like the lens when it does what it should and this problem is most likely due to the camera, since I can get it with the 20/1.7 as well. My other reasons are poor color (from the camera) and that I want shallower DOF, and I want one camera to do it all for me.

It also occurs with the 20/1.7 and at various distances. But it seems that
...Show more

Yes, it works as I said. (When pulling the focus ring making the manual focusing scale visible there are about ten discrete steps available. Still, a poor solution and more so for a "premium" lens.)

Makten wrote:
Umm, I didn't start the thread.

Edit: I seem to always find problems that no one else encounters. There are several explanations, and the two major ones would be that I'm very, very picky and that I don't use cameras like most other photographers do. I almost never shoot anything closer than 2 meters away for example, and 9 out of 10 lens test reports are dead wrong compared to what I see in my own images because of that.


Ooops. I have to admit I forgot about Sam's opening post. I'm now officially a very sloppy forum contributor. OTOH, I have made a third attempt, this time again at 5m (5.5) and at ISO200, f/2 and 1/6sec, handholding the camera standing up trying to find a problem. I took five pair of images time, first AF then MF pointing the camera towards different parts of the shelf and letting it focus on my hand between each image. Again no problems of any kind.

As you I believe you have a problem with your camera. (Unless I haven't missed about thousand threads all over the Net about the E-M5 with the 20/1.7 missing focus all the time...)

Lens reviewers very often shoot high contrast targets at short distances only. See how the serious (pretentious?) guys at Lenstip are convinced the Voigtländer 25/0.95 is the sharpest lens ever at the same time as they give us samples at long distances, lens stopped down, where the lens can't focus across the sensor to save its life. Or its place in the bag.

I hear you. If there only had been a good option I would have sold my E-M5 by now. My "problem" is that I want a FF camera with an EVF and lenses at least as good as the micro 4/3 ones. One camera doing it all is hard of course. I'm not that interested in buying/trying/buying/selling/trying/buying/selling/trying. When the Zeiss A-mount 50/1.4 comes (I have heard about the coming spring) I'll have a long hard look at the A99. Big and heavy but maybe a camera for me. In the meanwhile I'll have fun with the E-M5 despite its minimalist sensor.



Dec 01, 2012 at 08:54 PM
Jonas B
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p.2 #6 · p.2 #6 · OM-D out of focus infrequently.


I have checked with a couple of friends (one virtual, the others IRL sort of friends). My conclusion is that the problem described by Sam and Makten is not systematic but also not user error. There seem to be a number of cameras not working properly in all situations. That sounds weird and I may be wrong but that's how I interpret the testimonies.

Get your camera exchanged and/or rid of it.

What I have noticed is most cameras and Zuiko 12/2 lens work perfectly well. In low light combined with low contrast targets the camera sometimes fail to find focus. In some cases the green light lits up despite the AF just stopped working due to finding itself in a situation it can't handle. When this happens it is easily seen in the viewfinder and the cure is to focus manually. (This is best done with the camera set to AF+MF and without moving the focusing ring from its AF position. That way you'll come into the enlarged view mode (if activated) and you can focus precisely as the 10 (or so) distance zones associated with the snap focus mode aren't there.

A camera/lens giving you green light (or no light at all) being just out of focus is a camera in need of service.

The over all impression from the E-M5 and micro 4/3 lenses is that the AF is better and/or more reliable than most PDAF systems out there (unless talking about C-AF where the micro cameras lag compared to good PDAF systems).

If I'm wrong let me know. It's always good having things settled.



Dec 02, 2012 at 04:48 PM
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