Revisited Milky Way Nightscape + MFT capability considerations

Once home I have reprocessed the shots already shared here on my desktop and realised I had omitted some steps in my process so here are some updated files

Shots with GH5M2 PL12mm

This is a previous shot with the GH6 + PL15mm now that DxO is available

The shots are processed in Siril an astrophotography program on mac using standard techniques for deep space.

I then take the results in photoshop for blending as I do not use a one stop shop program like sequator as this only runs on PC

While deep space photography can certainly be done with small sensor and there a number of specialised cameras with MFT sensors nightscapes are actually more challenging

Frankly shooting a single exposure on MFT is very challenging and with all the noise reduction software you want you will go very high in ISO the DR will be low, the stars will clip and your image will look monochrome. You can try editing adding colors, dehaze etc but at the end it will not look as good as blending the shots.

In this field are the various fisheye lenses, the laowa 7.5 and any ultrawide lens

Then you move into stacking. I have maintained a table since a few years of the best lenses for Milky Way photography (the best for single shot being the PL12mm and other lenses 15-17mm good for mosaics or composites with more detail of the Milky Way)

Here MFT has two key issues.

1. When the sensor gets hot you get many pixel defects (hot pixels, glow etc)

2. The lens physical aperture is tiny due to the crop factor

The two issues above are of particular relevance as the 2 is mitigated by having longer exposure times while the first is impacted by exposure times.

In particular thermal noise goes linear with exposure however the benefit of stacking increases with the number of shots and the total exposure

What matters the most is that thermal noise depends more strongly on temperature than exposure time so if you can take your picture below 10C there will not be many pixel defects

I do not use dark frames as those are taken care by a raw editor however if you worked with raw files or dng you would need to take them and those will cure your hot and defective pixels as long as you take them in the same conditions otherwise they normally add noise.

A special mention are PDAF pixels, those show up with the process I use when the image is stressed so if you ever considered using an Olympus camera with PDAF pre OM-1 (there should not be a problem there) you need to take a whole set of flat, bias, dark frames in addition to your exposures otherwise you may end up with posterization issues and other nasty problem. I recommend not using a camera with PDAF and using one with nothing on your sensor. Please note the PDAF issue show up in any situation and are aggravated by thermal effects.

Finally when you do operate in a hot climate and you are taking your Milky Way shots in Thailand or similar there will be a disadvantage and you just need to make sure you don't end up with sensor glow that is hard to fix even with dark frames and destroys your image.

So other than the fact I need to spend more time imaging on the field to get the same result of a full frame camera (in effect 4 as much from 5' to 20') the results are pretty much the same for the Milky Way

Once you work with blending you know that you can take your foreground at twilight (my favourite is the nautical twilight) and this is not actually an issue for the format as the exposures will be short and if you want you can use LENR there are no visible issue once you crunch your exposure with a noise reduction program

So in short if you are prepare to do the work the challenges can be overcome but if you are expecting to snap away and get it looking great with a single shot you are going to face challenges. Obviously quality standards are personal and some people may say what I get is good enough

Finally my consideration is that the GH5M2 is the best camera for this job at present as it retains colors at high ISO this is important if you don't have a tracker an shoot at ISO 2000/2500. The OM-1 looks promising but I have not put my hands on one yet

The reprocessed images look spectacular.  Can you clarify, please, just to be clear, are these stacked or single images?

Thanks for the narrative. It all makes sense. Fortunately, up on the Teide plateau at night, too high a temperature isn't a problem

windmillgolfer wrote:

The reprocessed images look spectacular. Can you clarify, please, just to be clear, are these stacked or single images?

Thanks for the narrative. It all makes sense. Fortunately, up on the Teide plateau at night, too high a temperature isn't a problem

Yes those are stacked and blended more or less 20 or 25 minutes of exposure. If you don't have the large lens you need to make up with time

The Marbella shot is taken in April so was not that hot, summer time would be a problem

Very good, thank you.

tjl66 wrote:

Interceptor121 wrote:

A special mention are PDAF pixels, those show up with the process I use when the image is stressed so if you ever considered using an Olympus camera with PDAF pre OM-1 (there should not be a problem there) you need to take a whole set of flat, bias, dark frames in addition to your exposures otherwise you may end up with posterization issues and other nasty problem. I recommend not using a camera with PDAF and using one with nothing on your sensor. Please note the PDAF issue show up in any situation and are aggravated by thermal effects.

Sorry I disagree that there is a "PDAF issue" in Olympus cameras. When I asked you to point out these issues in this post you were not able to:

https://www.dpreview.com/forums/post/64823795

Here is a single unprocessed 15sec exposure from an em1 mark 2 opened directly in Maxim DL, no corrections whatsoever apart from a rough whitebalance. Can you point out the PDAF issues?

This is the key in bold

Here is a single unprocessed 15sec exposure from an em1 mark 2 opened directly in Maxim DL, no corrections whatsoever apart from a rough whitebalance. Can you point out the PDAF issues?

try to apply an Asinh or Histogram stretch. If you do not know what those are then you do not need to worry but your shot will be monochromatic like this example

The blue lines here help you see the stripes

You can obviously take dark frames as this at the end is fixed pattern but why bother?

If you pop over to some specialist groups you will see the most used Olympus camera is the EM10

All astrophotography specialist cameras with MFT and not sensor are of course contrast detect you do not want more issues than you need to handle

Interceptor121 wrote:

Once home I have reprocessed the shots already shared here on my desktop and realised I had omitted some steps in my process so here are some updated files

The shots are processed in Siril an astrophotography program on mac using standard techniques for deep space.

I then take the results in photoshop for blending as I do not use a one stop shop program like sequator as this only runs on PC

While deep space photography can certainly be done with small sensor and there a number of specialised cameras with MFT sensors nightscapes are actually more challenging

Frankly shooting a single exposure on MFT is very challenging and with all the noise reduction software you want you will go very high in ISO the DR will be low, the stars will clip and your image will look monochrome. You can try editing adding colors, dehaze etc but at the end it will not look as good as blending the shots.

In this field are the various fisheye lenses, the laowa 7.5 and any ultrawide lens

Then you move into stacking. I have maintained a table since a few years of the best lenses for Milky Way photography (the best for single shot being the PL12mm and other lenses 15-17mm good for mosaics or composites with more detail of the Milky Way)

Here MFT has two key issues.

1. When the sensor gets hot you get many pixel defects (hot pixels, glow etc)

2. The lens physical aperture is tiny due to the crop factor

The two issues above are of particular relevance as the 2 is mitigated by having longer exposure times while the first is impacted by exposure times.

In particular thermal noise goes linear with exposure however the benefit of stacking increases with the number of shots and the total exposure

What matters the most is that thermal noise depends more strongly on temperature than exposure time so if you can take your picture below 10C there will not be many pixel defects

I do not use dark frames as those are taken care by a raw editor however if you worked with raw files or dng you would need to take them and those will cure your hot and defective pixels as long as you take them in the same conditions otherwise they normally add noise.

A special mention are PDAF pixels, those show up with the process I use when the image is stressed so if you ever considered using an Olympus camera with PDAF pre OM-1 (there should not be a problem there) you need to take a whole set of flat, bias, dark frames in addition to your exposures otherwise you may end up with posterization issues and other nasty problem. I recommend not using a camera with PDAF and using one with nothing on your sensor. Please note the PDAF issue show up in any situation and are aggravated by thermal effects.

Finally when you do operate in a hot climate and you are taking your Milky Way shots in Thailand or similar there will be a disadvantage and you just need to make sure you don't end up with sensor glow that is hard to fix even with dark frames and destroys your image.

So other than the fact I need to spend more time imaging on the field to get the same result of a full frame camera (in effect 4 as much from 5' to 20') the results are pretty much the same for the Milky Way

Once you work with blending you know that you can take your foreground at twilight (my favourite is the nautical twilight) and this is not actually an issue for the format as the exposures will be short and if you want you can use LENR there are no visible issue once you crunch your exposure with a noise reduction program

So in short if you are prepare to do the work the challenges can be overcome but if you are expecting to snap away and get it looking great with a single shot you are going to face challenges. Obviously quality standards are personal and some people may say what I get is good enough

Finally my consideration is that the GH5M2 is the best camera for this job at present as it retains colors at high ISO this is important if you don't have a tracker an shoot at ISO 2000/2500. The OM-1 looks promising but I have not put my hands on one yet

Hi, I applaud you for your diligence in capturing those images, however, I wonder what your work would look like using a FF camera. I'm studying photography at an art institute and I've been able to see some amazing photographic works. Recently a student's astrophotography gallery was on display. Large stunning prints many poster size. Also a massive 8k tv which looped a slideshow. I was amazed at the detail and virtually noise free images. Brilliant colors and blacks incredibly black! The student's work was credited to a Nikon D800E and a Samyang 14mm 2.0. He was hosting his gallery and shared his technique and generously answered any questions. I asked him why he chose the D800E & the Samyang. Beyond the obvious in his consideration was his budget as a student. The cost for his kit was just under $800.00 US. Thats much less than the cost of a pro M43 lens.

I'm no pro photographer but as a recent M1X user, I soon found it's limitations compared to FF cameras I've had to opportunity to use at school. At this time I'm enjoying my M43 system, however if I were to do astrophotography, especially after seeing the amazing detail in FF, I think a dedicated investment of $800.00 would be money well spent rather than being crippled from the outset in M43. Just my thought's and not criticizing as think it's important to have an open mind in photography and not myopic with a brand,

Hornsbee wrote:

Interceptor121 wrote:

Once home I have reprocessed the shots already shared here on my desktop and realised I had omitted some steps in my process so here are some updated files

The shots are processed in Siril an astrophotography program on mac using standard techniques for deep space.

I then take the results in photoshop for blending as I do not use a one stop shop program like sequator as this only runs on PC

While deep space photography can certainly be done with small sensor and there a number of specialised cameras with MFT sensors nightscapes are actually more challenging

Frankly shooting a single exposure on MFT is very challenging and with all the noise reduction software you want you will go very high in ISO the DR will be low, the stars will clip and your image will look monochrome. You can try editing adding colors, dehaze etc but at the end it will not look as good as blending the shots.

In this field are the various fisheye lenses, the laowa 7.5 and any ultrawide lens

Then you move into stacking. I have maintained a table since a few years of the best lenses for Milky Way photography (the best for single shot being the PL12mm and other lenses 15-17mm good for mosaics or composites with more detail of the Milky Way)

Here MFT has two key issues.

1. When the sensor gets hot you get many pixel defects (hot pixels, glow etc)

2. The lens physical aperture is tiny due to the crop factor

The two issues above are of particular relevance as the 2 is mitigated by having longer exposure times while the first is impacted by exposure times.

In particular thermal noise goes linear with exposure however the benefit of stacking increases with the number of shots and the total exposure

What matters the most is that thermal noise depends more strongly on temperature than exposure time so if you can take your picture below 10C there will not be many pixel defects

I do not use dark frames as those are taken care by a raw editor however if you worked with raw files or dng you would need to take them and those will cure your hot and defective pixels as long as you take them in the same conditions otherwise they normally add noise.

A special mention are PDAF pixels, those show up with the process I use when the image is stressed so if you ever considered using an Olympus camera with PDAF pre OM-1 (there should not be a problem there) you need to take a whole set of flat, bias, dark frames in addition to your exposures otherwise you may end up with posterization issues and other nasty problem. I recommend not using a camera with PDAF and using one with nothing on your sensor. Please note the PDAF issue show up in any situation and are aggravated by thermal effects.

Finally when you do operate in a hot climate and you are taking your Milky Way shots in Thailand or similar there will be a disadvantage and you just need to make sure you don't end up with sensor glow that is hard to fix even with dark frames and destroys your image.

So other than the fact I need to spend more time imaging on the field to get the same result of a full frame camera (in effect 4 as much from 5' to 20') the results are pretty much the same for the Milky Way

Once you work with blending you know that you can take your foreground at twilight (my favourite is the nautical twilight) and this is not actually an issue for the format as the exposures will be short and if you want you can use LENR there are no visible issue once you crunch your exposure with a noise reduction program

So in short if you are prepare to do the work the challenges can be overcome but if you are expecting to snap away and get it looking great with a single shot you are going to face challenges. Obviously quality standards are personal and some people may say what I get is good enough

Finally my consideration is that the GH5M2 is the best camera for this job at present as it retains colors at high ISO this is important if you don't have a tracker an shoot at ISO 2000/2500. The OM-1 looks promising but I have not put my hands on one yet

Hi, I applaud you for your diligence in capturing those images, however, I wonder what your work would look like using a FF camera. I'm studying photography at an art institute and I've been able to see some amazing photographic works. Recently a student's astrophotography gallery was on display. Large stunning prints many poster size. Also a massive 8k tv which looped a slideshow. I was amazed at the detail and virtually noise free images. Brilliant colors and blacks incredibly black! The student's work was credited to a Nikon D800E and a Samyang 14mm 2.0. He was hosting his gallery and shared his technique and generously answered any questions. I asked him why he chose the D800E & the Samyang. Beyond the obvious in his consideration was his budget as a student. The cost for his kit was just under $800.00 US. Thats much less than the cost of a pro M43 lens.

I'm no pro photographer but as a recent M1X user, I soon found it's limitations compared to FF cameras I've had to opportunity to use at school. At this time I'm enjoying my M43 system, however if I were to do astrophotography, especially after seeing the amazing detail in FF, I think a dedicated investment of $800.00 would be money well spent rather than being crippled from the outset in M43. Just my thought's and not criticizing as think it's important to have an open mind in photography and not myopic with a brand,

It would look pretty much the same

My images stand out together with the very best on any system go check it out yourself and then you tell me

A larger sensor means you can capture the same shots with less exposures however at the end who cares when am out for the night and second I already had a second system and is a PITA to have a camera to do only one thing

If that was the only thing I was doing maybe I would consider it. To buy a dead weight camera like the canon 6D just for this am really not sure

tjl66 wrote:

Interceptor121 wrote:

This is the key in bold

Here is a single unprocessed 15sec exposure from an em1 mark 2 opened directly in Maxim DL, no corrections whatsoever apart from a rough whitebalance. Can you point out the PDAF issues?

try to apply an Asinh or Histogram stretch. If you do not know what those are then you do not need to worry but your shot will be monochromatic like this example

So what your saying is I need to stretch the image now? Well you need more exposure for that. No problem, here is 48x30sec with the same camera (em1.2) and the 40-150 f2.8 at 62mm f2.8, cropped in. This image is already as deep/or deeper than your images above so it should show the "PDAF issues" right? Can you point them out?

The blue lines here help you see the stripes

???

You can obviously take dark frames as this at the end is fixed pattern but why bother?

Why can't I see these defects in my em1 dark frames?

If you pop over to some specialist groups you will see the most used Olympus camera is the EM10

Which specialist groups? I certainly don't see this. I see plenty of people using em1's. Even if it were the case this would mean that more people own em10's than em1's.

All astrophotography specialist cameras with MFT and not sensor are of course contrast detect you do not want more issues than you need to handle

Which gets back to my original point, can you show me any evidence of "PDAF issues" in Olympus cameras when used for astrophotography.

Sorry I do not need to show anything to you. I have done my diligence and am not going to get back there I have already the best equipment for the job

The issues are with stretching and in some conditions the pixels flare this is a known fact a single exposure will not bring the issue to life

I tried using the EM1MKII on the field it was very frustrating and it has a number of ergonomic issues so why on earth would I bother using it anyway? If you want to give it a go up to you

How long the exposures are etc is irrelevant is stacking and stretching that brings out the issues this was already noted long time ago by Bill Claff when the camera came out

It would help if you stop hijacking my thread what other people do it is not my concern however getting the best performance is and I have sorted it out no need for more investigations

If someone asks me how to get the best results I give them an answer based on my experience that you do not like the answer is not something that concerns me

tjl66 wrote:

Interceptor121 wrote:

Sorry I do not need to show anything to you. I have done my diligence and am not going to get back there I have already the best equipment for the job

Great you have the best equipment for your job. But this still doesn't demonstrate the existence of Olympus "PDAF issues".

The issues are with stretching and in some conditions the pixels flare this is a known fact a single exposure will not bring the issue to life

How long the exposures are etc is irrelevant is stacking and stretching that brings out the issues this was already noted long time ago by Bill Claff when the camera came out

I posted a 24 minute stack above, made up of 48 exposures, that has been aggressively stretched. Surely this should show the Olympus "PDAF issues"?

It would help if you stop hijacking my thread what other people do it is not my concern however getting the best performance is and I have sorted it out no need for more investigations

This seems like a very relevant discussion under "MFT capability considerations". I am questioning the statement you made regarding Olympus cameras and issues with PDAF pixels since I cant find any evidence that this is a problem on any of my images.

Images talk by themselves where are yours that look like mine?

if you can’t see the wood from the trees is difficult to have a conversation

This is what I wrote you may want to read it again

A special mention are PDAF pixels, those show up with the process I use when the image is stressed so if you ever considered using an Olympus camera with PDAF pre OM-1 (there should not be a problem there) you need to take a whole set of flat, bias, dark frames in addition to your exposures otherwise you may end up with posterization issues and other nasty problem. I recommend not using a camera with PDAF and using one with nothing on your sensor. Please note the PDAF issue show up in any situation and are aggravated by thermal effects

tjl66 wrote:

Interceptor121

Interceptor & tji66 are both right - PDAF pixels do impact image noise BUT in many cases the impact is too small to be visible.

The important concern is visible FPN. No NR software can remove this problem. But not all cams w/ on sensor PDAF have visible FPN & not having PDAF is not guarantee the camera will not have visible FPN.

The Fuji X-T2 has PDAF pix only in the center portion of the frame. Here's a boosted 4 min. dark where you can see the area where those Pix are located:

I'm not sensor expert but I'm guessing the PDAF pix draw current & cause local heating so more noise.

Photons to Photos addresses the problem of FPN in the Sensor Heatmaps. The parameters to look at are DSNU & PRNU which measure non uniformity which can have several causes.

Some time back I tested the Oly E-M1.2 & the Pen F. As we know the later does not have PDAF. Here are full size jpg MW images from stacks of 4 30" images using the lovely Oly 17mm f1.2 - the sharpest astro lens I've ever seen. These were ArcSin stretched. Both images show plenty of noise - it was a warm night. More importantly, neither show any FPN.

Note the DSNU & PRNU values for several M43 cams:

EM1.2 25% 0.5%

Pen F 8% 0.4%

GH5.2 8% 0.5%

OM1 12% 0.4%

The OM1 shows good improvement almost matching the Pen but w/ higher QE.  On this same evening, I shot w/ my Fuji X-T100 which does have 91 PDAF BUT non-uniformity values that are the same as the Pen F.

Not so different.

As an aside, this copy of the MZ17mm Pro has mild field curvature which makes it unusable at f1.2:

From my experience, m43 has 2 major weaknesses - IBIS & the floating sensor results in rapid sensor heating. The second is fundamental. The shorter FL for the same FOV from m43 means less light gathering. The main solutions to the last issue is use longer FL and stitch.

Hope this helps.

wrote:

This is the key in bold

Here is a single unprocessed 15sec exposure from an em1 mark 2 opened directly in Maxim DL, no corrections whatsoever apart from a rough whitebalance. Can you point out the PDAF issues?

try to apply an Asinh or Histogram stretch. If you do not know what those are then you do not need to worry but your shot will be monochromatic like this example

So what your saying is I need to stretch the image now? Well you need more exposure for that. No problem, here is 48x30sec with the same camera (em1.2) and the 40-150 f2.8 at 62mm f2.8, cropped in. This image is already as deep/or deeper than your images above so it should show the "PDAF issues" right? Can you point them out?

The blue lines here help you see the stripes

???

You can obviously take dark frames as this at the end is fixed pattern but why bother?

Why can't I see these defects in my em1 dark frames?

If you pop over to some specialist groups you will see the most used Olympus camera is the EM10

Which specialist groups? I certainly don't see this. I see plenty of people using em1's. Even if it were the case this would mean that more people own em10's than em1's.

All astrophotography specialist cameras with MFT and not sensor are of course contrast detect you do not want more issues than you need to handle

Which gets back to my original point, can you show me any evidence of "PDAF issues" in Olympus cameras when used for astrophotography.

Awesome photos Interceptor121.

I have been using StarryLandscapeStacker on my Mac. I have a Pen-F and an E-M1 MkII, plus the PL15 and the Oly 8mm fisheye.

Can you please tell me a bit more about your process? I gather you set up your camera on a tripod and take a foreground exposure before it gets too dark, then wait for the Milkyway to become visible in the right location? Do you then take multiple short exposures using relatively low ISO and short shutter speeds and then stack and process these in Siril? Do you use Bias / Flats / Darks at all, or just rely on the Light frames?

Many thanks

tradesmith45 wrote:

tjl66 wrote:

Interceptor121

Interceptor & tji66 are both right - PDAF pixels do impact image noise BUT in many cases the impact is too small to be visible.

The important concern is visible FPN. No NR software can remove this problem. But not all cams w/ on sensor PDAF have visible FPN & not having PDAF is not guarantee the camera will not have visible FPN.

The Fuji X-T2 has PDAF pix only in the center portion of the frame. Here's a boosted 4 min. dark where you can see the area where those Pix are located:

I'm not sensor expert but I'm guessing the PDAF pix draw current & cause local heating so more noise.

Photons to Photos addresses the problem of FPN in the Sensor Heatmaps. The parameters to look at are DSNU & PRNU which measure non uniformity which can have several causes.

Some time back I tested the Oly E-M1.2 & the Pen F. As we know the later does not have PDAF. Here are full size jpg MW images from stacks of 4 30" images using the lovely Oly 17mm f1.2 - the sharpest astro lens I've ever seen. These were ArcSin stretched. Both images show plenty of noise - it was a warm night. More importantly, neither show any FPN.

you can see horizontal lines more prominent in the first image a tad higher than the tallest mountain those are not present in the other image from the PEN-F

Note the DSNU & PRNU values for several M43 cams:

EM1.2 25% 0.5%

Pen F 8% 0.4%

GH5.2 8% 0.5%

OM1 12% 0.4%

The OM1 shows good improvement almost matching the Pen but w/ higher QE. On this same evening, I shot w/ my Fuji X-T100 which does have 91 PDAF BUT non-uniformity values that are the same as the Pen F.

The issue with all the PDAF models is that black levels are really high especially at high ISO this causes white balance flicker and loss of color accuracy at higher ISO which you can easily see on DxOMark color sensitivity charts

Fixed Pattern noise as I wrote can be managed taking dark and flat frames that are otherwise not required. I use neither on the GH5M2 but a camera with PDAF is more likely to need them

Not so different.

As an aside, this copy of the MZ17mm Pro has mild field curvature which makes it unusable at f1.2:

From my experience, m43 has 2 major weaknesses - IBIS & the floating sensor results in rapid sensor heating. The second is fundamental. The shorter FL for the same FOV from m43 means less light gathering. The main solutions to the last issue is use longer FL and stitch.

Hope this helps.

heat building has to do with many things and as defective pixels grow more with temperature than they do with exposure time temperature control is very important however this is for most depending on ambient temperature the camera is rarely much warmer in my experience. So if you go and try those shots where is 25 degrees at night you will have much worse results than being at 10 degrees

wrote:

This is the key in bold

Here is a single unprocessed 15sec exposure from an em1 mark 2 opened directly in Maxim DL, no corrections whatsoever apart from a rough whitebalance. Can you point out the PDAF issues?

try to apply an Asinh or Histogram stretch. If you do not know what those are then you do not need to worry but your shot will be monochromatic like this example

So what your saying is I need to stretch the image now? Well you need more exposure for that. No problem, here is 48x30sec with the same camera (em1.2) and the 40-150 f2.8 at 62mm f2.8, cropped in. This image is already as deep/or deeper than your images above so it should show the "PDAF issues" right? Can you point them out?

The blue lines here help you see the stripes

???

You can obviously take dark frames as this at the end is fixed pattern but why bother?

Why can't I see these defects in my em1 dark frames?

If you pop over to some specialist groups you will see the most used Olympus camera is the EM10

Which specialist groups? I certainly don't see this. I see plenty of people using em1's. Even if it were the case this would mean that more people own em10's than em1's.

All astrophotography specialist cameras with MFT and not sensor are of course contrast detect you do not want more issues than you need to handle

Which gets back to my original point, can you show me any evidence of "PDAF issues" in Olympus cameras when used for astrophotography.

tjl66 wrote:

tradesmith45 wrote:

tjl66 wrote:

Interceptor121

Interceptor & tji66 are both right - PDAF pixels do impact image noise BUT in many cases the impact is too small to be visible.

Agree, but It is being made out to be an issue, when it is in fact a non-issue. Particularly with milky way images which are not particularly demanding.

again totally incorrect. As long lenses are guided and have bigger physical aperture deep space is actually less demanding on a small sensor than wide field with short focal

The important concern is visible FPN. No NR software can remove this problem. But not all cams w/ on sensor PDAF have visible FPN & not having PDAF is not guarantee the camera will not have visible FPN.

Absolutely, there are lot more sources for FPN than PDAF. Take a series of Bias frames average them and stretch them as much as possible and you will see all manner of fixed structures - on any sensor. Likewise do that with a flat field.

Fixed pattern noise is driven by defective pixels

defective pixels are those that do not produce an image

PDAF pixels do not produce an image so by definition they are defective pixel in fpn context that are arranged in row and therefore create patterns more than random hot pixels or cold pixels would do

this requires you to take dark frames for optimal results in all conditions which in turn means time and less optimal results

RobPNth wrote:

Awesome photos Interceptor121.

I have been using StarryLandscapeStacker on my Mac. I have a Pen-F and an E-M1 MkII, plus the PL15 and the Oly 8mm fisheye.

I would use the pen and the 15mm

Can you please tell me a bit more about your process? I gather you set up your camera on a tripod and take a foreground exposure before it gets too dark, then wait for the Milkyway to become visible in the right location? Do you then take multiple short exposures using relatively low ISO and short shutter speeds and then stack and process these in Siril? Do you use Bias / Flats / Darks at all, or just rely on the Light frames?

Many thanks

-- hide signature --

RobPNth
http://www.myfathersworld.net.nz
Excio: https://excio.gallery/robert

With my set up I only use light frames unless it is really hot. I still take some just to clearly see if I had any glow in some cases but don’t use them

in terms of the process my exposures are normally around 30” tracked and whatever I can manage depending on lens and location if I just have a tripod

normally I study the location first and depending on where I am I take foreground shots at twilight sometimes this is before other times after the milky way. There is a trend to take foreground shots at blue hour which is civil twilight the shots appear a bit unreal for my taste

while as a beginner it may be very tempting to use software like sequator that manages foreground and background together the two require different exposures so if your image is too bright you clip the stars if it is set for the stars the foreground is too dark so after you get some experience you tend to do the blending yourself in photoshop

tjl66 wrote:

Interceptor121 wrote:

tjl66 wrote:

Interceptor121 wrote:

Sorry I do not need to show anything to you. I have done my diligence and am not going to get back there I have already the best equipment for the job

Great you have the best equipment for your job. But this still doesn't demonstrate the existence of Olympus "PDAF issues".

The issues are with stretching and in some conditions the pixels flare this is a known fact a single exposure will not bring the issue to life

How long the exposures are etc is irrelevant is stacking and stretching that brings out the issues this was already noted long time ago by Bill Claff when the camera came out

I posted a 24 minute stack above, made up of 48 exposures, that has been aggressively stretched. Surely this should show the Olympus "PDAF issues"?

It would help if you stop hijacking my thread what other people do it is not my concern however getting the best performance is and I have sorted it out no need for more investigations

This seems like a very relevant discussion under "MFT capability considerations". I am questioning the statement you made regarding Olympus cameras and issues with PDAF pixels since I cant find any evidence that this is a problem on any of my images.

Images talk by themselves where are yours that look like mine?

No problem, even though most of my astrophotography is at longer focal lengths I had this image taken last year with an em1.2 and 17mm f1.2 lens at f2.0 which is of the same region of sky as yours. Its a 10 stack of 60 second images. I've also reprocessed with ASinh (way more saturation than I normally like) but it gives us a basis of comparison. Being at 17mm f1.2 set at f2.0 has more resolution, but the physical aperture being 8.5mm is similar to the 12mm f1.4. I assume the total exposure is similar.

Is this image with or without dark frame subtraction?

if you can’t see the wood from the trees is difficult to have a conversation

This is what I wrote you may want to read it again

A special mention are PDAF pixels, those show up with the process I use when the image is stressed so if you ever considered using an Olympus camera with PDAF pre OM-1 (there should not be a problem there) you need to take a whole set of flat, bias, dark frames in addition to your exposures otherwise you may end up with posterization issues and other nasty problem. I recommend not using a camera with PDAF and using one with nothing on your sensor. Please note the PDAF issue show up in any situation and are aggravated by thermal effects

Yes read it and still don't agree.

You don't know what my process is hence it is not possible for you to agree or disagree