Olympus 25mm problem... or Operator problem?

Started Jul 26, 2014 | Discussions
BHPhotog Contributing Member • Posts: 812
Olympus 25mm problem... or Operator problem?

These two shots were taken in the same way, same time, etc. with my new Olympus f/1.8, tripod mounted, IS off, 2 second delay, auto WB. Matrix metering, one is AF and the other is manual focus on exactly the same spot.

I'm used to the 'kit' 12-50 with a widest f/3.5 aperture, so this kind of narrow DOF is new to me and I don't know what's going on. Is the aperture causing the camera to AF somewhere else than what it shows in the VF? Do I have to always use manual focus at this wide an aperture?

Any and all comments appreciate...

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lambert4
lambert4 Senior Member • Posts: 2,287
Re: Olympus 25mm problem... or Operator problem?

It just appears to me that the AF chose slightly behind the subject, for some reason.  Probably not an issue just verify focus is on what you wish.

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OP BHPhotog Contributing Member • Posts: 812
Re: OP response

lambert4 wrote:

It just appears to me that the AF chose slightly behind the subject, for some reason.

I agree, and that's what concerns me. I'm not always going to want to double check focus manually.

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hindesite Veteran Member • Posts: 3,389
Re: Olympus 25mm problem... or Operator problem?
2

BHPhotog wrote:

These two shots were taken in the same way, same time, etc. with my new Olympus f/1.8, tripod mounted, IS off, 2 second delay, auto WB. Matrix metering, one is AF and the other is manual focus on exactly the same spot.

Yeah, but what AF scheme were you using? You haven't said, and that is probably the most important information.

(BTW, looks painful

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(unknown member) Senior Member • Posts: 3,010
Re: OP response

lambert4 wrote:

It just appears to me that the AF chose slightly behind the subject, for some reason.

I agree, and that's what concerns me. I'm not always going to want to double check focus manually.

Is this a common occurrence with this lens? I like to suggest you repeat it numerous times say 10 and then see what happens. I would focus the camera some where else each time and then refocus on the test subject.

Guy Parsons
Guy Parsons Forum Pro • Posts: 29,182
Which AF box?
1

Are you using the smallest AF box (via latest firmware), or using the smallest Magnify AF box?

If a larger AF box the camera often sees better contrast behind where you intended so focuses there instead.

Regards.... Guy

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Skeeterbytes Forum Pro • Posts: 13,480
Re: Olympus 25mm problem... or Operator problem?

hindesite wrote:

BHPhotog wrote:

These two shots were taken in the same way, same time, etc. with my new Olympus f/1.8, tripod mounted, IS off, 2 second delay, auto WB. Matrix metering, one is AF and the other is manual focus on exactly the same spot.

Yeah, but what AF scheme were you using? You haven't said, and that is probably the most important information.

(BTW, looks painful

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Yup, if you want concise focus, select small, single-dot SAF and double-check your release priority setting. This should be a piece of cake.

Cheers,

Rick

p.s. The 25 is a great little lens.

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SkiHound Veteran Member • Posts: 3,107
Re: Olympus 25mm problem... or Operator problem?

Don't know what your focal point was. I pretty much always use a small single point. You certainly need to be much more careful with a fast lens and large aperture. I can set my 17mm lens at somewhere around 10' and f/10 and get almost everything in reasonable focus. A 25mm at f/1.8 just doesn't have much depth of field. Don't know if this is user error or not since I don't know the focus point, but shooting at f/1.8 you need to be pretty precise.

OP BHPhotog Contributing Member • Posts: 812
OP response #2

SkiHound wrote:

Don't know what your focal point was.

The focus point is marked on the image...

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OP BHPhotog Contributing Member • Posts: 812
OP response #3

Skeeterbytes wrote:

Yup, if you want concise focus, select small, single-dot SAF and double-check your release priority setting. This should be a piece of cake.

Cheers,

Rick

p.s. The 25 is a great little lens.

I agree about that, but it kinda defeats the purpose of using the 25 as a general walk-around lens with matrix metering. For setup shots, the smallest single point and manual focus works with the large apertures, but if I have to go up to f/4 or f/5.6 to use it for an all purpose lens I can get 95% of the same IQ from the 12-50 @ 25mm and f/5.6 with a lot more flexibility.

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OP BHPhotog Contributing Member • Posts: 812
OP response #4

Guy Parsons wrote:

Are you using the smallest AF box (via latest firmware), or using the smallest Magnify AF box?

If a larger AF box the camera often sees better contrast behind where you intended so focuses there instead.

Regards.... Guy

Yep. I have the AF box at the smallest and same with the magnify.See response #3 for some further thoughts...

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Skeeterbytes Forum Pro • Posts: 13,480
Re: OP response #3

I use center-diamond AF pattern for general walking around but switch to single-dot when I want concise focus. Don't think I've tried this lens with CAF+Tr so can't comment on its abilities there. With such a fast lens, very high shutter speeds are accessible for action shots, which is a good thing.

E-M1 25/1.8

Cheers,

Rick

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jack Hoggard
jack Hoggard Contributing Member • Posts: 825
Re: Olympus 25mm problem... or Operator problem?

Which is which?

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jaxupra

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jack Hoggard
jack Hoggard Contributing Member • Posts: 825
Re: Olympus 25mm problem... or Operator problem?

You said one is autofocus and one is manual.  The first (left) image is fine, which I assume to be AF, and the second (right) is not - manual?

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jaxupra

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OP BHPhotog Contributing Member • Posts: 812
OP response #5

jack Hoggard wrote:

You said one is autofocus and one is manual. The first (left) image is fine, which I assume to be AF, and the second (right) is not - manual?

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jaxupra

Nope, the other way around. The AF is on the right, and it has focused on the background to the left of the mannequin; the MF (focus acquired using the lens focus ring override, but the camera is still in AF) for is on the left and that is focused on the mannequin (box area). That's the issue, the AF is picking something off-center to focus on.

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Guy Parsons
Guy Parsons Forum Pro • Posts: 29,182
Re: OP response #5

BHPhotog wrote:

jack Hoggard wrote:

You said one is autofocus and one is manual. The first (left) image is fine, which I assume to be AF, and the second (right) is not - manual?

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jaxupra

Nope, the other way around. The AF is on the right, and it has focused on the background to the left of the mannequin; the MF (focus acquired using the lens focus ring override, but the camera is still in AF) for is on the left and that is focused on the mannequin (box area). That's the issue, the AF is picking something off-center to focus on.

Earlier on in the forum there were some suspicions that the AF leaks outside the indicated focus box. Maybe it's something for me to test one rainy day when there's nothing else to do.

When things look tricky I often use the 2x DTC (assigned to Red button in my case) to give a quick check of the AF, then recover the full image from the RAW.

Regards..... Guy

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OP BHPhotog Contributing Member • Posts: 812
Re: OP response #6

I'm sorry, but I don't understand what this means:

When things look tricky I often use the 2x DTC (assigned to Red button in my case) to give a quick check of the AF, then recover the full image from the RAW.

What is "DTC" and what has RAW to do with the focus point?

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Guy Parsons
Guy Parsons Forum Pro • Posts: 29,182
Re: OP response #6

BHPhotog wrote:

I'm sorry, but I don't understand what this means:

When things look tricky I often use the 2x DTC (assigned to Red button in my case) to give a quick check of the AF, then recover the full image from the RAW.

What is "DTC" and what has RAW to do with the focus point?

Using a 2x DTC magnified view it is easier to see if the AF (or MF) worked properly.

Shooting Menu 1 - Digital Tele-Converter - On/Off, in my case assigned to the Red button.

If taking the shot with 2x on then the middle 4MP is interpolated up to 16MP to make the jpeg, meanwhile the RAW file is the full 4:3 original 16MP frame.

Regards..... Guy

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Optical1
Optical1 Senior Member • Posts: 1,096
3 Questions:

1) Were you close to the minimum focus distance for this lens (~10in)?  In some cases, when the focus cannot rack past the focus point, the camera will give up and not focus properly.

2) Can you expand on your procedure with the AF shot?  I'm struggling to think of why you would proceed with taking the picture if you didn't attain focus.  Did you fully press the shutter button to take your shot without half-pressing to attain focus?  If so, the camera will simply wait the two seconds (from your delay) and then expose.

3) Do you have "release priority" enabled?

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Bob Tullis
Bob Tullis Forum Pro • Posts: 34,780
Re: Olympus 25mm problem... or Operator problem?
2

In addition to some advice already offered, the contrast here is stronger on the b/g than on the subject, and unless you insure the AF area is solely on the subject you may well expect this result.   Not understanding this would fall under operator error.  While AF is good in general, there are times one needs to take command (or give up and blame the gear).

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