E-M1 Focus problems

Started Mar 13, 2014 | Discussions
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lnikj OP Regular Member • Posts: 190
Re: E-M1 Focus problems

Mark Chan wrote:

lnikj wrote:

Mark Chan wrote:

May I suggest overexposure, possibly implicating diffraction?

i try dialing down exposure in strong daylight. The photos I get with positive exposure compensation seem similar and indeed it may be difficult to find where u focused.

I was wondering about whether my practice of ETTR was making it worse.

I don't understand the relationship between overexposure and diffraction though. Can you explain further?

Cheers

PS I have some more test shots to share later. I'm sure now that it is not simply diffraction (though that plays a small part). I am reasonably sure now that shutter speed is the single biggest factor here.

-- hide signature --

went back and seeing your aperture it shouldn't be defraction.

by the way, another possible problem will be say shooting in broad daylight with aperture wide open but again that's not your problem.

exposing ETTR is an issue as OLY cameras tend to overexpose in daylight and underexposed indoors. What I do, for my needs, is in outdoor environs I underexpose, and overexpose indoors.

I ETTR for two reasons:

1. The E-M1 is noisy at base ISO.

2. In low contrast scenes outside the E-M1 determinedly sticks the exposure and histogram dead centre when there is often a whole stop of headroom above.

The latter gives more data to work with in the image (you can see this just by looking at the resulting file size).

None of my test shots are ETTR; they are underexposed if anything.

I do feel using ETTR maybe causing the problem.

I am happy to stop ETTRing if it is causing the problem but my (genuine) question as I stated before is: What is the relationship between overexposure and diffraction?

i don't find the focusing issue, and this is with ep-3, ep-5, em-5, em1 and epl-2...but then that's just my perspective.

i do hope you find a fix

Thanks.

-- hide signature --
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Big Ga Forum Pro • Posts: 18,404
Re: Stuff happens

DonSC wrote:

Big Ga wrote:

DonSC wrote:

If you want to rule out an equipment issue, take the shot handheld and then use a tripod at both above and below sync speed (1/250). See if there is a difference.

Why are you using the sync speed as a reference?

If it's related to vibrations, from the shutter or not, then the blur pattern will be different above and below sync speed.

I realise that if its a vibration issue, then below certain speed(s) it will diminish in effect, and similarly above, but what I am asking is: why are you using the sync speed as the reference centre point?

lnikj OP Regular Member • Posts: 190
Re: E-M1 Focus problems

Just received a PM pointing me to this:

http://www.dpreview.com/reviews/image-comparison?attr18=daylight&attr13_0=oly_em1&attr13_1=oly_em1&attr13_2=oly_em1&attr13_3=oly_em1&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=200&attr16_1=400&attr16_2=800&attr16_3=1600&normalization=full&widget=1&x=-0.5542356121036323&y=0.3080535591217879

In the above:

ISO200 1/80

ISO400 1/160

ISO800 1/320

ISO1600 1/640

High ISO but high shutter speed shots sharper than Low ISO lower shutter speed shots.

Another counterintuitive result that confirms my findings.

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DonSC Senior Member • Posts: 1,032
Re: Stuff happens

Big Ga wrote

I realise that if its a vibration issue, then below certain speed(s) it will diminish in effect, and similarly above, but what I am asking is: why are you using the sync speed as the reference centre point?

It's not that the blurring would be more or less, it's that the blurring would fit a fundamentally different pattern. This follows from the fact that above sync speed the second curtain is closing while the first curtain is opening. The top/bottom of the image has already been fully exposed before the first curtain could create any vibration.

Mark Chan Senior Member • Posts: 1,713
Re: E-M1 Focus problems

Mark Chan wrote:

lnikj wrote:

Mark Chan wrote:

May I suggest overexposure, possibly implicating diffraction?

i try dialing down exposure in strong daylight. The photos I get with positive exposure compensation seem similar and indeed it may be difficult to find where u focused.

I was wondering about whether my practice of ETTR was making it worse.

I don't understand the relationship between overexposure and diffraction though. Can you explain further?

Cheers

PS I have some more test shots to share later. I'm sure now that it is not simply diffraction (though that plays a small part). I am reasonably sure now that shutter speed is the single biggest factor here.

-- hide signature --

went back and seeing your aperture it shouldn't be defraction.

by the way, another possible problem will be say shooting in broad daylight with aperture wide open but again that's not your problem.

exposing ETTR is an issue as OLY cameras tend to overexpose in daylight and underexposed indoors. What I do, for my needs, is in outdoor environs I underexpose, and overexpose indoors.

I ETTR for two reasons:

1. The E-M1 is noisy at base ISO.

2. In low contrast scenes outside the E-M1 determinedly sticks the exposure and histogram dead centre when there is often a whole stop of headroom above.

The latter gives more data to work with in the image (you can see this just by looking at the resulting file size).

None of my test shots are ETTR; they are underexposed if anything.

I do feel using ETTR maybe causing the problem.

I am happy to stop ETTRing if it is causing the problem but my (genuine) question as I stated before is: What is the relationship between overexposure and diffraction?

i don't find the focusing issue, and this is with ep-3, ep-5, em-5, em1 and epl-2...but then that's just my perspective.

i do hope you find a fix

Thanks.

-- hide signature --

Hiya,

The term shouldn't be diffraction - I kinda messed that term up. It should be 'longitudinal chromatic aberration' i was referring to, but again not in your pics as I experienced this with large aperture lens shot in broad daylight wide open. This caused my images to be very 'unclear'.

Having said that, I would postulate; if diffraction occurs, wouldn't overexposure further reduce sharpness of the image hence you receive an unfocused image?

I would also note of a recent experience; using my EP-5 with 25mmf1.4, I somehow could get the camera to focus on subjects - the background would always be in focus. Ultimately I switched it off pulled batteries and it worked as normal again.

Still miss the no-nonsense cameras of the film era.

Big Ga Forum Pro • Posts: 18,404
Re: Stuff happens

DonSC wrote:

Big Ga wrote

I realise that if its a vibration issue, then below certain speed(s) it will diminish in effect, and similarly above, but what I am asking is: why are you using the sync speed as the reference centre point?

It's not that the blurring would be more or less, it's that the blurring would fit a fundamentally different pattern. This follows from the fact that above sync speed the second curtain is closing while the first curtain is opening. The top/bottom of the image has already been fully exposed before the first curtain could create any vibration.

I know what you're getting at, and you MIGHT be right, but on what basis do you state that " blurring would fit a fundamentally different pattern" ?

How do you know?

DonSC Senior Member • Posts: 1,032
Re: Stuff happens

Big Ga wrote:

I know what you're getting at, and you MIGHT be right, but on what basis do you state that " blurring would fit a fundamentally different pattern" ?

How do you know?

It would have to be. If the second curtain closes before the first curtain finishes opening then vibrations from the first curtain couldn't produce blurring. Couldn't be otherwise.

NewGirlLiz Regular Member • Posts: 423
Re: E-M1 Focus problems - a solution

Hi there. I'm not sure if you have resolved your AF problem, but I have recently discovered the exact same thing. (Second row from the bottom not focusing.) Following a suggestion from another DPreview member, I updated my camera's firmware to version 1:1, and the problem has been completely resolved! Just thought I'd let you know in case you want to try it too.

Best wishes

Liz

thxbb12 Senior Member • Posts: 1,855
My guess

I think your issue is either of these 2 things (or a mixture of both):

  1. Shutter shock
  2. Faulty AF

The last picture totally looks like shutter shock to me. Up to f/8, diffraction won't significantly affect your image quality.  I also own an E-M1 and I shoot landscapes between f/5.6 and f/8 and I can hardly tell them apart when pixel peeping.

Your last image clearly looks like shutter shock to me.  The first 2 are difficult to gauge. The thing is, DOF is so large with MFT that if you are above f/5.6, most of the image is in focus and there will always be a good portion of the scene that's very sharp.  Unfortunately it doesn't seem to be the case with your pics.  I have a hard time believing you're doing something very wrong, especially given you have a D300.

I'd send the body back to Olympus to get it checked.  Shutter shock happens, but it's a rare occurrence.  It happens to me once in a while (very annoying), but it's rare. When it happens it looks very much like your last shot. Your body may have a mechanical issue regarding the shutter or the AF or both. That would be my bet.

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lnikj OP Regular Member • Posts: 190
Re: My guess

thxbb12 wrote:

I think your issue is either of these 2 things (or a mixture of both):

  1. Shutter shock
  2. Faulty AF

The last picture totally looks like shutter shock to me. Up to f/8, diffraction won't significantly affect your image quality. I also own an E-M1 and I shoot landscapes between f/5.6 and f/8 and I can hardly tell them apart when pixel peeping.

Your last image clearly looks like shutter shock to me. The first 2 are difficult to gauge. The thing is, DOF is so large with MFT that if you are above f/5.6, most of the image is in focus and there will always be a good portion of the scene that's very sharp. Unfortunately it doesn't seem to be the case with your pics. I have a hard time believing you're doing something very wrong, especially given you have a D300.

I'd send the body back to Olympus to get it checked. Shutter shock happens, but it's a rare occurrence. It happens to me once in a while (very annoying), but it's rare. When it happens it looks very much like your last shot. Your body may have a mechanical issue regarding the shutter or the AF or both. That would be my bet.

Hi Florent

Thanks. I pretty much think its shutter shock.

It's back with Olympus (who currently have 'misplaced' it) with my test shots.

We'll see what happens.

Cheers.

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Big Ga Forum Pro • Posts: 18,404
Re: Stuff happens

DonSC wrote:

Big Ga wrote:

I know what you're getting at, and you MIGHT be right, but on what basis do you state that " blurring would fit a fundamentally different pattern" ?

How do you know?

It would have to be. If the second curtain closes before the first curtain finishes opening then vibrations from the first curtain couldn't produce blurring. Couldn't be otherwise.

Hmmm. Care to elaborate further, or perhaps define what specifically would be 'fundamentally different' in the pattern ?

amoneys2k New Member • Posts: 1
Re: My guess

Thanks. I pretty much think its shutter shock.

It's back with Olympus (who currently have 'misplaced' it) with my test shots.

We'll see what happens.

Hello,

I'm curious if you got your E-M1 back and if the replacement/repaired unit has the same issue.

I'm seeing a similar issue myself.

Thanks.

carlosvp Regular Member • Posts: 193
Re: The third image

lnikj wrote:

As you guessed I was focusing at my rough estimate of the Hyperfocal distance. I will try the alternative next time.

It may also depend on how you're estimating.  If you're using rough estimates based on your experience with full-frame digital, you'll be off, as the m4/3 sensors are higher pixel density (and therefore the circle-of-confusion part of the hyperfocal distance calculation will be off).

Using a hyperfocal distance calculator that has a circle-of-confusion size setting appropriate to m4/3 sensors may be all you need to change.

C.

David Kieltyka
David Kieltyka Veteran Member • Posts: 4,676
Re: E-M1 Focus problems - a solution

Yes, in fact the firmware update did fix the focusing issue!

Edit: I'm refering to v1.4 of the camera's firmware.

-Dave-

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