High res and long exposure noise reduction

[Throwback]

I have been long searching to no avail, so would be grateful for any practical experience on a particular issue with high resolution mode and noise reduction in long exposures.

By way of background, I use a Lumix G9 a lot for long-exposure photos of gloomy building interiors, always using a tripod. I often want to maximize resolution as I am recording historic fabric before and during conservation works, but when using high-res mode I am limited to a 1 sec longest shutter (the limit of the electronic shutter) and also by the fact that there is no dark frame subtraction (unlike in the normal mode). As a result, hot pixels are not eliminated and appear quite large (multi-pixel) due to the pixel shifting: they are a real pain to remove in post, especially as I want to retain detail.

So I am exploring alternative cameras. Obviously, I could use a decent resolution full-frame camera without the need for pixel shifting, but that is where I came from: in my fifties I got tired of lugging my Nikon D810 and several large lenses (14-24mm etc.) up scaffolding and ladders etc., and have otherwise enjoyed the compactness of M43, esp. in terms of lens size. So I am wondering about M43 alternatives.

Sadly, the GH6 didn't adopt the S5's advances in long-exposure high-res mode, so has the same limitations as the G9 in this regard: the S5 high-res mode was improved to allow longer exposures (8 sec max, which would pretty much be OK for me) and dark frame subtraction noise reduction. Of course, any future G9 mk2 may be similar to the S5 in this regard, but we have no certainty about this or indeed that there will even be a G9 mk2.

Finally, then, the question: how does the OM-1 implement high-resolution mode in terms of long exposures and noise reduction? I have searched, read the OM-1 manual and have so far found no answer. Is the OM-1 electronic shutter of 60 secs the limit on the exposure of a tripod-mode high-resolution photo? Can long exposure noise reduction (dark frame subtraction) be used in high-resolution mode? And, finally, if both these are the case, is this as effective at removing hot pixels in high-resolution mode as it is in normal mode?

Sorry for such a long post, but, hopefully, this makes things clear.

Many thanks - in anticipation - for anyone using an OM-1 in this way.

Cheers,

Roland

 

[ahaslett]

I’d get a used Sony A7Rii with Tamron 17-28/2.8. Pretty light, good resolution, and not that expensive. If you want even more resolution, used A7Riv’s are getting much cheaper with the launch of the A7Rv.

The A7Rii has limitations, but is ideal for thoughtful shooting off a tripod. It even has a pixel shift mode if you need one. Or you could stitch with MFT and get the advantages of Brenizer.

Although I have an OM1, my apologies for not using it in the way you need!

Andrew

--
Infinite are the arguments of mages. Truth is a jewel with many facets. Ursula K LeGuin
Please feel free to edit any images that I post

 

[leorimkus]

Not a 100% solution - but you can manually make a dark frame image and apply it in PP. With some experimentation you can define how often you need to make such image. I believe hot pixels should be pretty stable.

 

[Throwback]

I’d get a used Sony A7Rii with Tamron 17-28/2.8. Pretty light, good resolution, and not that expensive. If you want even more resolution, used A7Riv’s are getting much cheaper with the launch of the A7Rv.

The A7Rii has limitations, but is ideal for thoughtful shooting off a tripod. It even has a pixel shift mode if you need one. Or you could stitch with MFT and get the advantages of Brenizer.

Although I have an OM1, my apologies for not using it in the way you need!

Andrew

Thanks Andrew, but I was really after specific info as per my OP!

As I said, I had a capable Nikon FF set-up, but found that too heavy and bulky (and also wanted to go mirrorless due to ageing eyes finding an EVF easier than an LCD for manual focus): if returning to FF, I would have no need to go Nikon (sold it all), but would still need a 14mm or wider lens, decent longer focal length macro etc., so it all gets heavy again. And, of course, expensive to change system again. Hence, as per my OP, really wanting to find out if other M43 options would work.

Cheers,

Roland

 

[ahaslett]

I’d get a used Sony A7Rii with Tamron 17-28/2.8. Pretty light, good resolution, and not that expensive. If you want even more resolution, used A7Riv’s are getting much cheaper with the launch of the A7Rv.

The A7Rii has limitations, but is ideal for thoughtful shooting off a tripod. It even has a pixel shift mode if you need one. Or you could stitch with MFT and get the advantages of Brenizer.

Although I have an OM1, my apologies for not using it in the way you need!

Andrew

Thanks Andrew, but I was really after specific info as per my OP!

As I said, I had a capable Nikon FF set-up, but found that too heavy and bulky (and also wanted to go mirrorless due to ageing eyes finding an EVF easier than an LCD for manual focus): if returning to FF, I would have no need to go Nikon (sold it all), but would still need a 14mm or wider lens, decent longer focal length macro etc., so it all gets heavy again. And, of course, expensive to change system again. Hence, as per my OP, really wanting to find out if other M43 options would work.

Cheers,

Roland

Understood, sorry I can’t be more help.

Andrew

 

[Adrian Harris]

I have been long searching to no avail, so would be grateful for any practical experience on a particular issue with high resolution mode and noise reduction in long exposures.

By way of background, I use a Lumix G9 a lot for long-exposure photos of gloomy building interiors, always using a tripod. I often want to maximize resolution as I am recording historic fabric before and during conservation works, but when using high-res mode I am limited to a 1 sec longest shutter (the limit of the electronic shutter) and also by the fact that there is no dark frame subtraction (unlike in the normal mode). As a result, hot pixels are not eliminated and appear quite large (multi-pixel) due to the pixel shifting: they are a real pain to remove in post, especially as I want to retain detail.

So I am exploring alternative cameras. Obviously, I could use a decent resolution full-frame camera without the need for pixel shifting, but that is where I came from: in my fifties I got tired of lugging my Nikon D810 and several large lenses (14-24mm etc.) up scaffolding and ladders etc., and have otherwise enjoyed the compactness of M43, esp. in terms of lens size. So I am wondering about M43 alternatives.

Sadly, the GH6 didn't adopt the S5's advances in long-exposure high-res mode, so has the same limitations as the G9 in this regard: the S5 high-res mode was improved to allow longer exposures (8 sec max, which would pretty much be OK for me) and dark frame subtraction noise reduction. Of course, any future G9 mk2 may be similar to the S5 in this regard, but we have no certainty about this or indeed that there will even be a G9 mk2.

Finally, then, the question: how does the OM-1 implement high-resolution mode in terms of long exposures and noise reduction? I have searched, read the OM-1 manual and have so far found no answer. Is the OM-1 electronic shutter of 60 secs the limit on the exposure of a tripod-mode high-resolution photo? Can long exposure noise reduction (dark frame subtraction) be used in high-resolution mode? And, finally, if both these are the case, is this as effective at removing hot pixels in high-resolution mode as it is in normal mode?

Sorry for such a long post, but, hopefully, this makes things clear.

Many thanks - in anticipation - for anyone using an OM-1 in this way.

Cheers,

Roland

Ho Roland. I use OM1 and older olympus hi-res mode cameras frequently. This sensor shift in this mode seems to cancel hot pixels very well (I say that because I haven't spotted any yet.

The 60sec electronic shutter allows use of low ISO in hi-res mode if needed, but even at high iso's noise cancells very well and detail improves dramatically.

 

[Throwback]

Not a 100% solution - but you can manually make a dark frame image and apply it in PP. With some experimentation you can define how often you need to make such image. I believe hot pixels should be pretty stable.

Thanks Leo. There are a few issues with this: a) I have a lot of images b) I have to archive raw .dng files c) we aren't talking about single pixels, but a block each time - due to multiple shifted frames being combines - with varying intensity across the block d) the number of dead pixels/blocks changes as the sensor heats.

Not to waste people's kindly meant interventions, but is there anyone with an OM-1 who has tried long exposure high-resolution photos and knows the answer to my two main questions (i.e. longest shutter in hi-res mode, and whether noise reduction works in this mode)?

Cheers,

Roland

 

[Throwback]

I have been long searching to no avail, so would be grateful for any practical experience on a particular issue with high resolution mode and noise reduction in long exposures.

By way of background, I use a Lumix G9 a lot for long-exposure photos of gloomy building interiors, always using a tripod. I often want to maximize resolution as I am recording historic fabric before and during conservation works, but when using high-res mode I am limited to a 1 sec longest shutter (the limit of the electronic shutter) and also by the fact that there is no dark frame subtraction (unlike in the normal mode). As a result, hot pixels are not eliminated and appear quite large (multi-pixel) due to the pixel shifting: they are a real pain to remove in post, especially as I want to retain detail.

So I am exploring alternative cameras. Obviously, I could use a decent resolution full-frame camera without the need for pixel shifting, but that is where I came from: in my fifties I got tired of lugging my Nikon D810 and several large lenses (14-24mm etc.) up scaffolding and ladders etc., and have otherwise enjoyed the compactness of M43, esp. in terms of lens size. So I am wondering about M43 alternatives.

Sadly, the GH6 didn't adopt the S5's advances in long-exposure high-res mode, so has the same limitations as the G9 in this regard: the S5 high-res mode was improved to allow longer exposures (8 sec max, which would pretty much be OK for me) and dark frame subtraction noise reduction. Of course, any future G9 mk2 may be similar to the S5 in this regard, but we have no certainty about this or indeed that there will even be a G9 mk2.

Finally, then, the question: how does the OM-1 implement high-resolution mode in terms of long exposures and noise reduction? I have searched, read the OM-1 manual and have so far found no answer. Is the OM-1 electronic shutter of 60 secs the limit on the exposure of a tripod-mode high-resolution photo? Can long exposure noise reduction (dark frame subtraction) be used in high-resolution mode? And, finally, if both these are the case, is this as effective at removing hot pixels in high-resolution mode as it is in normal mode?

Sorry for such a long post, but, hopefully, this makes things clear.

Many thanks - in anticipation - for anyone using an OM-1 in this way.

Cheers,

Roland

Ho Roland. I use OM1 and older olympus hi-res mode cameras frequently. This sensor shift in this mode seems to cancel hot pixels very well (I say that because I haven't spotted any yet.

The 60sec electronic shutter allows use of low ISO in hi-res mode if needed, but even at high iso's noise cancells very well and detail improves dramatically.

Adrian, you are a star! That's very helpful.

Good to know the 60s electronic shutter applies to hi-res mode.

And when you say 'the sensor shift...seems to cancel hot pixels very well', obviously, the pixel shift itself won't do this (as witness the G9 and GH6 problem), so are you certain that a dark frame is being subtracted, rather than you have been lucky (as, indeed, I am with the G9 quite often)? That is, if you set a long exposure - say a few seconds - have you heard the extra frame being taken/seen any other evidence of noise reduction being applied (e.g. message on camera)?

Cheers,

Roland

 

[400trix]

I have been long searching to no avail, so would be grateful for any practical experience on a particular issue with high resolution mode and noise reduction in long exposures.

By way of background, I use a Lumix G9 a lot for long-exposure photos of gloomy building interiors, always using a tripod. I often want to maximize resolution as I am recording historic fabric before and during conservation works, but when using high-res mode I am limited to a 1 sec longest shutter (the limit of the electronic shutter) and also by the fact that there is no dark frame subtraction (unlike in the normal mode). As a result, hot pixels are not eliminated and appear quite large (multi-pixel) due to the pixel shifting: they are a real pain to remove in post, especially as I want to retain detail.

So I am exploring alternative cameras. Obviously, I could use a decent resolution full-frame camera without the need for pixel shifting, but that is where I came from: in my fifties I got tired of lugging my Nikon D810 and several large lenses (14-24mm etc.) up scaffolding and ladders etc., and have otherwise enjoyed the compactness of M43, esp. in terms of lens size. So I am wondering about M43 alternatives.

Sadly, the GH6 didn't adopt the S5's advances in long-exposure high-res mode, so has the same limitations as the G9 in this regard: the S5 high-res mode was improved to allow longer exposures (8 sec max, which would pretty much be OK for me) and dark frame subtraction noise reduction. Of course, any future G9 mk2 may be similar to the S5 in this regard, but we have no certainty about this or indeed that there will even be a G9 mk2.

Finally, then, the question: how does the OM-1 implement high-resolution mode in terms of long exposures and noise reduction? I have searched, read the OM-1 manual and have so far found no answer. Is the OM-1 electronic shutter of 60 secs the limit on the exposure of a tripod-mode high-resolution photo? Can long exposure noise reduction (dark frame subtraction) be used in high-resolution mode? And, finally, if both these are the case, is this as effective at removing hot pixels in high-resolution mode as it is in normal mode?

Sorry for such a long post, but, hopefully, this makes things clear.

Many thanks - in anticipation - for anyone using an OM-1 in this way.

Cheers,

Roland

Ho Roland. I use OM1 and older olympus hi-res mode cameras frequently. This sensor shift in this mode seems to cancel hot pixels very well (I say that because I haven't spotted any yet.

The 60sec electronic shutter allows use of low ISO in hi-res mode if needed, but even at high iso's noise cancells very well and detail improves dramatically.

Adrian, you are a star! That's very helpful.

Good to know the 60s electronic shutter applies to hi-res mode.

And when you say 'the sensor shift...seems to cancel hot pixels very well', obviously, the pixel shift itself won't do this (as witness the G9 and GH6 problem), so are you certain that a dark frame is being subtracted, rather than you have been lucky (as, indeed, I am with the G9 quite often)? That is, if you set a long exposure - say a few seconds - have you heard the extra frame being taken/seen any other evidence of noise reduction being applied (e.g. message on camera)?

Cheers,

Roland

Doesn't the G9 have a pixel mapping mode that effectively turns off hot pixels?

 

[ahaslett]

Not a 100% solution - but you can manually make a dark frame image and apply it in PP. With some experimentation you can define how often you need to make such image. I believe hot pixels should be pretty stable.

Thanks Leo. There are a few issues with this: a) I have a lot of images b) I have to archive raw .dng files c) we aren't talking about single pixels, but a block each time - due to multiple shifted frames being combines - with varying intensity across the block d) the number of dead pixels/blocks changes as the sensor heats.

Not to waste people's kindly meant interventions, but is there anyone with an OM-1 who has tried long exposure high-resolution photos and knows the answer to my two main questions (i.e. longest shutter in hi-res mode, and whether noise reduction works in this mode)?

Cheers,

Roland

I just tried with my OM1 in a darkened room with a moderate DR scene.

At ISO 100 f6.3, I got 8s exposure, which seemed to be 8s for each exposure. After the exposures were done, there was a significant gap before it started Busy, ie merging the shots. There was a shutter sound at the beginning and end of this gap, seems like LENR.

Bumping up the ISO to give 1/1.3s exposure seemed to miss out this gap, but it’s hard to be sure.

Can I just check:

1 You are using pixels shift on a tripod, not handheld hi-res?

2 You have recently run pixel mapping?

3 The scene is really so dark that you need to combine multiple long exposure shots?

Sorry if these are silly questions.

Andrew

 

[knickerhawk]

I have been long searching to no avail, so would be grateful for any practical experience on a particular issue with high resolution mode and noise reduction in long exposures.

By way of background, I use a Lumix G9 a lot for long-exposure photos of gloomy building interiors, always using a tripod. I often want to maximize resolution as I am recording historic fabric before and during conservation works, but when using high-res mode I am limited to a 1 sec longest shutter (the limit of the electronic shutter) and also by the fact that there is no dark frame subtraction (unlike in the normal mode). As a result, hot pixels are not eliminated and appear quite large (multi-pixel) due to the pixel shifting: they are a real pain to remove in post, especially as I want to retain detail.

So I am exploring alternative cameras. Obviously, I could use a decent resolution full-frame camera without the need for pixel shifting, but that is where I came from: in my fifties I got tired of lugging my Nikon D810 and several large lenses (14-24mm etc.) up scaffolding and ladders etc., and have otherwise enjoyed the compactness of M43, esp. in terms of lens size. So I am wondering about M43 alternatives.

Sadly, the GH6 didn't adopt the S5's advances in long-exposure high-res mode, so has the same limitations as the G9 in this regard: the S5 high-res mode was improved to allow longer exposures (8 sec max, which would pretty much be OK for me) and dark frame subtraction noise reduction. Of course, any future G9 mk2 may be similar to the S5 in this regard, but we have no certainty about this or indeed that there will even be a G9 mk2.

Finally, then, the question: how does the OM-1 implement high-resolution mode in terms of long exposures and noise reduction? I have searched, read the OM-1 manual and have so far found no answer. Is the OM-1 electronic shutter of 60 secs the limit on the exposure of a tripod-mode high-resolution photo? Can long exposure noise reduction (dark frame subtraction) be used in high-resolution mode? And, finally, if both these are the case, is this as effective at removing hot pixels in high-resolution mode as it is in normal mode?

Sorry for such a long post, but, hopefully, this makes things clear.

Many thanks - in anticipation - for anyone using an OM-1 in this way.

Cheers,

Roland

Ho Roland. I use OM1 and older olympus hi-res mode cameras frequently. This sensor shift in this mode seems to cancel hot pixels very well (I say that because I haven't spotted any yet.

I just checked an experiment I did with my EM1iii in Tripod HR mode. I see clear evidence of hot pixels in these shots. Here's an example (note the stuck green pixels toward the left side, for instance):

While the OP's question is about the OM1 and not the EM1iii, I doubt that the OM1 operates differently in this regard.

The 60sec electronic shutter allows use of low ISO in hi-res mode if needed, but even at high iso's noise cancells very well and detail improves dramatically.

 

[Throwback]

Doesn't the G9 have a pixel mapping mode that effectively turns off hot pixels?

Thanks.

It does have pixel mapping, and I refresh this from time to time, but I'm not certain that it applies to hi-res: I still seem to be getting issues. And, of course, long exposure noise reduction isn't just about pixels.

Cheers,

Roland

 

[ahaslett]

I have been long searching to no avail, so would be grateful for any practical experience on a particular issue with high resolution mode and noise reduction in long exposures.

By way of background, I use a Lumix G9 a lot for long-exposure photos of gloomy building interiors, always using a tripod. I often want to maximize resolution as I am recording historic fabric before and during conservation works, but when using high-res mode I am limited to a 1 sec longest shutter (the limit of the electronic shutter) and also by the fact that there is no dark frame subtraction (unlike in the normal mode). As a result, hot pixels are not eliminated and appear quite large (multi-pixel) due to the pixel shifting: they are a real pain to remove in post, especially as I want to retain detail.

So I am exploring alternative cameras. Obviously, I could use a decent resolution full-frame camera without the need for pixel shifting, but that is where I came from: in my fifties I got tired of lugging my Nikon D810 and several large lenses (14-24mm etc.) up scaffolding and ladders etc., and have otherwise enjoyed the compactness of M43, esp. in terms of lens size. So I am wondering about M43 alternatives.

Sadly, the GH6 didn't adopt the S5's advances in long-exposure high-res mode, so has the same limitations as the G9 in this regard: the S5 high-res mode was improved to allow longer exposures (8 sec max, which would pretty much be OK for me) and dark frame subtraction noise reduction. Of course, any future G9 mk2 may be similar to the S5 in this regard, but we have no certainty about this or indeed that there will even be a G9 mk2.

Finally, then, the question: how does the OM-1 implement high-resolution mode in terms of long exposures and noise reduction? I have searched, read the OM-1 manual and have so far found no answer. Is the OM-1 electronic shutter of 60 secs the limit on the exposure of a tripod-mode high-resolution photo? Can long exposure noise reduction (dark frame subtraction) be used in high-resolution mode? And, finally, if both these are the case, is this as effective at removing hot pixels in high-resolution mode as it is in normal mode?

Sorry for such a long post, but, hopefully, this makes things clear.

Many thanks - in anticipation - for anyone using an OM-1 in this way.

Cheers,

Roland

Ho Roland. I use OM1 and older olympus hi-res mode cameras frequently. This sensor shift in this mode seems to cancel hot pixels very well (I say that because I haven't spotted any yet.

I just checked an experiment I did with my EM1iii in Tripod HR mode. I see clear evidence of hot pixels in these shots. Here's an example (note the stuck green pixels toward the left side, for instance):

While the OP's question is about the OM1 and not the EM1iii, I doubt that the OM1 operates differently in this regard.

The 60sec electronic shutter allows use of low ISO in hi-res mode if needed, but even at high iso's noise cancells very well and detail improves dramatically.

Would LENR remove stuck pixels? Isn’t that the job of pixel mapping.

Andrew

--
Infinite are the arguments of mages. Truth is a jewel with many facets. Ursula K LeGuin
Please feel free to edit any images that I post

 

[Throwback]

I just tried with my OM1 in a darkened room with a moderate DR scene.

At ISO 100 f6.3, I got 8s exposure, which seemed to be 8s for each exposure. After the exposures were done, there was a significant gap before it started Busy, ie merging the shots. There was a shutter sound at the beginning and end of this gap, seems like LENR.

Bumping up the ISO to give 1/1.3s exposure seemed to miss out this gap, but it’s hard to be sure.

Can I just check:

1 You are using pixels shift on a tripod, not handheld hi-res?

2 You have recently run pixel mapping?

3 The scene is really so dark that you need to combine multiple long exposure shots?

Sorry if these are silly questions.

Andrew

Thanks for testing Andrew. That seems pretty conclusive re the long exposure noise reduction happening with the 8s exposure. Great!

To answer your questions:

1. Yes, I am using pixel shift on a tripod. Indeed, all my interior photos on a tripod. That said, I quite fancy a camera that can do handheld hi res, for my external photos, where I currently have to use a tripod if I want hi res: that's why I was disappointed with the GH6 not having the S5's advances for longer exposure hi res.

2. Yes, I run pixel mapping from time to time, including today.

3. Hmm, not sure I follow you. I am often taking photos that could do with more than 1 sec (the G9's annoying limit): dark interiors of cathedrals, castles and colleges, inc. unlit roof spaces (I'm a buildings archaeologist). Ideally at base ISO a with a reasonable depth of field (usually aperture of 5.6). So often could do with 1-16 secs. I do like the way HR pics reduce noise as much as anything, but, even so, don't like being forced to bump up the iso due to the G9's 1 sec electronic shutter limit. The multiple exposures aspect of high res doesn't change the exposure, of course.

[And, just for ref, I have been taking such architectural photos for 40 years (moving from 5x4 and medium format to digital SLRs a long time ago: M43 is the smallest format I have used, and I love the weight/bulk reduction!].

Cheers,

Roland

 

[Throwback]

ahaslett wrote

Would LENR remove stuck pixels? Isn’t that the job of pixel mapping.

Andrew

Thanks for this, both, but I'm not quite sure how the Olympus/OM cameras work in this regard: and I'm not even sure that long exposure noise reduction applied in the test image which used a 1/4 sec shutter. Does it apply to such short exposures?

Cheers,

R

 

[gary0319]

• I use often Hand Held Hi Rez (HHHR) for lowlight, night street images often, both with my OM-1 and now more often with the OM-5.

It took me a while to get over my idea that night photography required long exposures times at low ISO. The beauty of HHHR is that the stacking process is really good at eliminating noise, so right now my go to ISO for night street and low light HHHR is ISO 3200. That’s a bunch of stops that can be used to punch up the shutter speed. Even ISO 6400 and 12,800 work with a bit of help from DeNoise AI. SOOC HHHR image below at ISO 3200, no additional NR.

But, you can still use a lower ISO, if you take advantage of the great Image stabilization in recent cameras. Second image below from my previous E-M1 III HHHR at ISO 320, total handheld time was 4 seconds.


OM-5, ISO 3200


1/4 sec shutter speed X HHHR 16 images = 4 seconds total handheld.

 

[Danielvr]

Maybe you could ask an OM-1 owner to take a few high res shots according to your specifications (in terms of settings, light, subject etc), and send the resulting files to you for closer inspection. Then use tools like OM Workspace and Rawdigger to see if the OM-1 does what you need.

 

[Throwback]

Thanks Gary. Not least for the pics.

Yes, the slower shutter speeds one can use handheld have certainly made a difference. But with no handheld hi-res mode on the G9, and the need to get reliably focused, well-composed interiors, sometimes aiming a bit of additional lighting away from the camera, I'm mostly using a tripod: no great hardship, as this has been the case all my working life. As and when cameras allow, I'm happy enough to reduce tripod dependency: not least, I'm keen to be able to have a camera with handheld hi-res mode for external architectural photos.

I certainly notice the difference going above base ISO in high-res mode on the G9, and there's no need to do that, except when the 1 sec max exposure forces my hand. As for post processing, as I said, I'm archiving raw dng files and dealing with a mass of record shots, so I need decent shots in camera.

Cheers,

Roland

 

[Danielvr]

Would LENR remove stuck pixels? Isn’t that the job of pixel mapping.

Pixel mapping works on a camera firmware level, is performed beforehand by the user, and it changes how bad pixels are filtered out when images are taken. Mapped-out pixels are replaced by color/brightness values from their surrounding pixels. It affects all shots.

LENR (aka dark frame substraction) is applied automatically by the camera when a long exposure has been made and it only affects the current image. Bright values in the black frame (i.e. bad pixels) are deducted from the corresponding pixels in the actual image.

 

[Throwback]

Maybe you could ask an OM-1 owner to take a few high res shots according to your specifications (in terms of settings, light, subject etc), and send the resulting files to you for closer inspection. Then use tools like OM Workspace and Rawdigger to see if the OM-1 does what you need.

Thanks Daniel. Seemed cheeky to ask, but certainly very happy to receive one or two well-exposed photos of a dim interior from an OM-1 in hi res tripod mode, with exposure of, say, 8 secs with noise reduction applied. Would the tools you mention reveal use of noise reduction?

Cheers,

Roland