Full frame osc vs mono apsc

Topic starter

Sep 2, 2023 · Edited: Sep 2, 2023

Hey guys,

my gear acquisition syndrom gives me headache right now.
I have saved up for a new cooled camera and i am unsure if i should go full frame osc (asi2400 / 6200mc) or if i should go mono apsc (2600mm).

full frame mono isn’t an option because i don’t want to spend that much money.

imaging scope is an esprit 120 that would support a full frame sensor, at least with the flattener not so sure about the 0.77 flattener reducer.

Happy to hear a few opinions on that.

cs
andi

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apennine104

Sep 2, 2023

Hi Andi, Just my opinion:

I would go 2600MM. I started with a 294MM, and then built a small rig based on the 2600MC. In my limited experience I prefer the mono image quality. I know there is math to back it up, but the mono camera just produces sharper images with more SNR from what I can tell visually when used for an equal amount of exposure time as a OSC. I also enjoy the flexibility of discrete narrowband filters and the ability to gather pure luminance.

I also feel like full frame opens up a can of worms with tilt and having to very minutely adjust back spacing as you work at the corner stars in that huge field of view.

Good luck with your decision!

Helpful

Sean Mc

Sep 2, 2023

If there was a poll, I would vote mono.

George Yendrey

Sep 2, 2023 · Edited: Sep 2, 2023

Mono all the way. Having shot both OSC and Mono in APS-C cameras, I can tell you that the quality of raw frames, the efforts to process and quality of the final processed image are all going to be better.

The thing to understand is that with an OSC is that your image isn't really 9576*6388 pixels for every channel (RGB). It is 1/4 of that for R and B, and 1/2 for G (the bayer matrix for most OSC is RGGB). The cameral electronics interpolate to fill in the "blanks" but there is always a loss of detail. In my experience, I suspect this is responsible to some extent for the higher noise/color mottling that is such a pain to mitigate in OSC post processing.

Getting back to the 'raw' data, that means your full frame OSC for the R and B channels is providing "real" data for 2394x1597 pixels and interpolating the rest. For the G/G pixels you get a matrix of 4788x3194 and the remainder are interpolated by the camera electronics.

The APS-C mono camera is providing 6248*4176 for every frame/filter combination.

I started with an OSC camera, and I think OSC make a great starting place since the acquisition portion is simpler (point and shoot and minimal filter requirements). Once a person as done that for a while, worked out the kinks/preferences with equipment, sequencing software, post processing software, etc, then it is (IMO) a natural progression to mono. It also allows the person to decide if they are "just" a casual imager, prefer visual, or enthusiastic/obsessive/compulsive enough to not find the requirements for mono imaging daunting.

The reason I say this is that mono data acquisition is more involved since you have to shoot an image for LRGB or SHO (for narrow band) or some combination. That pretty much requires adding a filter wheel if you haven't already. It also means that getting data for given target can take more than one night and due to weather may extend out several weeks (or even to the following imaging season, it happens).

I was pretty reluctant to make the change, even though others on Astrobin had been nudging me to go that direction. Uwe Deutermann finally pushed me over the edge to the dark side. Once I worked through the different work flow that mono requires and saw the final image, I've never even considered going back.

YMMV
CS
Clayton

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George Yendrey

Sep 2, 2023

Andi,
I'll add one more little tidbit.
While I feel like it is possible to tell the difference, keep in mind that even on galleries like those in Astrobin, the images posted are reduced in file size/image quality from the original "final" versions like the PixInsight .xisf file format.

For example, my most recent posting of NGC 6729, had a final image/file size of 141 mb in the PixInsight native xisf file format. The posted (100% quality from PixInsight) jpeg is not quite 6 mb.

So the image "quality" while good on galleries like Astrobin, it NOT as good as the real final image in its native format.

When I compare the OSC and MONO images I've shot for the same target with the OSC and Mono versions of the same sensor (ASI2600MM and ASI2600MC), the differences in detail and quality between the OSC and mono camera versions is VERY apparent, IMO.

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Anderl

Topic starter

Sep 2, 2023

Andi,
I'll add one more little tidbit.
While I feel like it is possible to tell the difference, keep in mind that even on galleries like those in Astrobin, the images posted are reduced in file size/image quality from the original "final" versions like the PixInsight .xisf file format.

For example, my most recent posting of NGC 6729, had a final image/file size of 141 mb in the PixInsight native xisf file format. The posted (100% quality from PixInsight) jpeg is not quite 6 mb.

So the image "quality" while good on galleries like Astrobin, it NOT as good as the real final image in its native format.

When I compare the OSC and MONO images I've shot for the same target with the OSC and Mono versions of the same sensor (ASI2600MM and ASI2600MC), the differences in detail and quality between the OSC and mono camera versions is VERY apparent, IMO.

Thank you for taking time and giving me such valuable information!

looks like i am either going mono apsc or a having a bad day by telling my wife that we won’t go on vacation cause of a fullframe mono setup.

cs
andi

George Yendrey

Sep 2, 2023 · Edited: Sep 2, 2023

Andi,
I'll add one more little tidbit.
While I feel like it is possible to tell the difference, keep in mind that even on galleries like those in Astrobin, the images posted are reduced in file size/image quality from the original "final" versions like the PixInsight .xisf file format.

For example, my most recent posting of NGC 6729, had a final image/file size of 141 mb in the PixInsight native xisf file format. The posted (100% quality from PixInsight) jpeg is not quite 6 mb.

So the image "quality" while good on galleries like Astrobin, it NOT as good as the real final image in its native format.

When I compare the OSC and MONO images I've shot for the same target with the OSC and Mono versions of the same sensor (ASI2600MM and ASI2600MC), the differences in detail and quality between the OSC and mono camera versions is VERY apparent, IMO.

Thank you for taking time and giving me such valuable information!

looks like i am either going mono apsc or a having a bad day by telling my wife that we won’t go on vacation cause of a fullframe mono setup.

cs
andi

Heh,
Yea, good luck with that!!!

I've thought about full frame and there are many in use to be found on Astrobin. The primary consideration (there are others) when considering a full frame CMOS astro camera is your OTA image circle.

For example the diagonal measurement of the ZWO ASI6200MM-P is 43.3 mm. The image circle for my OTA is 40mm (admittedly the SkyWatcher Esprit line of refractors all have smaller image circles than the other comparable refractors on the market). So for my setup, full frame is a non-starter, and definitely a no-go with a field reducer. The Starizona Apex-L 0.63 FF/FR made specifically for the Esprit line of refractors further reduces the image circle to 30mm which creates vignetting even with the APS-C sensor size.

If you never intend to use a field reducer (FR), then a 50mm image circle is a good minimum for use with a full frame camera/sensor. If you intend to use a Field Reducer at some point, then 60mm should be your minimum but you'd need to find the image circle for the field reducer for your OTA. If I remember correctly, the Stellarvue SVC130T has an image circle of 60mm but with the OEM field reducer that drops to 40mm which would cause some vignetting with a full frame. On the other hand their SVX152T has a monstrous 90mm image circle with just the flattener and is in the 50-60mm range with the field reducer.

The other issue with full frame is sensor tilt. It is also an issue with APS-C sensor size, but is more significant with the full frame (and now meduim format size) sensors. To insure optimal sensor tilt, using something like the ASG Photon Cage and modern software tools like the Aberration Inspector in the HocusFocus add-on for N.I.N.A. is all but mandatory - IMO. ASG has some good YouTube videos on their Photon Cage, as well as some good discussions on sensor tilt, and the tools to deal with it.

YMMV
CS
Clayton

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Adrian

Sep 2, 2023

Andi,
I'll add one more little tidbit.
While I feel like it is possible to tell the difference, keep in mind that even on galleries like those in Astrobin, the images posted are reduced in file size/image quality from the original "final" versions like the PixInsight .xisf file format.

For example, my most recent posting of NGC 6729, had a final image/file size of 141 mb in the PixInsight native xisf file format. The posted (100% quality from PixInsight) jpeg is not quite 6 mb.

So the image "quality" while good on galleries like Astrobin, it NOT as good as the real final image in its native format.

When I compare the OSC and MONO images I've shot for the same target with the OSC and Mono versions of the same sensor (ASI2600MM and ASI2600MC), the differences in detail and quality between the OSC and mono camera versions is VERY apparent, IMO.

Hi George,
Just as an aside, you can post PNG files to AstroBin and they can be significantly larger than JPEGs and also preserve more of the quality.

Well Written Concise

Stjepan Prugovečki

Sep 2, 2023

The larger FOV that full frame brings can be compensated by smaller chip (mosaic) . The advantages mono brings compared to OSC can not, so mono all the way . Although, pricing comparison should be done carefully, as a good set of filters and filterwheel can cost almost like the camera itself .

George Yendrey

Sep 2, 2023

Adrian:
Andi,
I'll add one more little tidbit.
While I feel like it is possible to tell the difference, keep in mind that even on galleries like those in Astrobin, the images posted are reduced in file size/image quality from the original "final" versions like the PixInsight .xisf file format.

For example, my most recent posting of NGC 6729, had a final image/file size of 141 mb in the PixInsight native xisf file format. The posted (100% quality from PixInsight) jpeg is not quite 6 mb.

So the image "quality" while good on galleries like Astrobin, it NOT as good as the real final image in its native format.

When I compare the OSC and MONO images I've shot for the same target with the OSC and Mono versions of the same sensor (ASI2600MM and ASI2600MC), the differences in detail and quality between the OSC and mono camera versions is VERY apparent, IMO.

Hi George,
Just as an aside, you can post PNG files to AstroBin and they can be significantly larger than JPEGs and also preserve more of the quality.

Thanks, I'll give PNG a try. JPEG was sort of the goto image format from way back, so other than tiff for processing in Adobe I've not looked at much of anything else.

Brian Boyle

Sep 2, 2023

Mostly mono for me too. If you are shooting mostly galaxies, then there is a "convenience" argument for OSC. But then you probably wouldn't need FF OSC.
If shooting most nebulae with an OSC, you may get tired of red. I did, and switched from the 2400MC [great camera] to a 6200MM [another great camera] - at least on my RC8 scope.

I still shoot wide-field with the 2400MC using my Nikon 200mm lens, but I haven't gone back to OSC on my telescope.

CS Brian

George Yendrey

Sep 2, 2023 · Edited: Sep 2, 2023

Brian Boyle:
Mostly mono for me too. If you are shooting mostly galaxies, then there is a "convenience" argument for OSC. But then you probably wouldn't need FF OSC.
If shooting most nebulae with an OSC, you may get tired of red. I did, and switched from the 2400MC [great camera] to a 6200MM [another great camera] - at least on my RC8 scope.

I still shoot wide-field with the 2400MC using my Nikon 200mm lens, but I haven't gone back to OSC on my telescope.

CS Brian

Having not done any planetary imaging, its nothing I have experience with. However, what little I do know makes me think that an OSC camera might be a good fit for planetary imaging as long as the camera has a sufficiently high frame rate. I don't know if they still do, but at one time ZWO listed their ASI294MC-P as both a DSO and planetary camera. I don't remember what its frame rate is/was.

Roman Pearah

Sep 2, 2023 · Edited: Sep 2, 2023

The cameral electronics interpolate to fill in the "blanks" but there is always a loss of detail.

Only if you do the incorrect thing and demosaic. If you CFA Drizzle instead, you will recover said detail. Always Drizzle OSC data. The Bayer matrix is its own form of undersampling.

Rafał Szwejkowski

IOTD Staff

Sep 3, 2023

Actually 6200MC is not far off mono these days and going full frame would give you nice options with your Esprit 120. If you have decent sky and your scope can support FF it's the better choice. If you're under bad sky and/or into narrowband, only then mono crop sensor might be the better choice.

Concise

PhilHD925

Sep 3, 2023

Roman Pearah:
The cameral electronics interpolate to fill in the "blanks" but there is always a loss of detail.

Only if you do the incorrect thing and demosaic. If you CFA Drizzle instead, you will recover said detail. Always Drizzle OSC data. The Bayer matrix is its own form of undersampling.

I do the same thing with my 2400MC and 268C data. I always drizzle 1x and dither at least every other sub, or 1 out of 3 if my exposures are short. I'm not sure if dithering plays a huge role when drizzling 1x, I know for sure it's imperative when drizzling 2x or more. I only drizzle 2x when using the reducer on my SVX130T.

Does drizzling at least 1x bypass interpolation entirely? I would love to know how all this works, and if I'm wasting my time. I have noticed the colors look a little better when compared to regular debayering, no drizzle.

Thanks

Phil

Mark

Sep 3, 2023

I have found that shooting mono from my backyard is futile as I don't get enough clear skies. So I have reverted to OSC at home and have put mono at remote observatory where I can take my time to gather all the data I want. I don't think people put enough emphasis on the sky when making these decisions. I didn't. And now I have a spare unused mono camera!

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Stjepan Prugovečki

Sep 3, 2023

Mark:
I have found that shooting mono from my backyard is futile as I don't get enough clear skies. So I have reverted to OSC at home and have put mono at remote observatory where I can take my time to gather all the data I want. I don't think people put enough emphasis on the sky when making these decisions. I didn't. And now I have a spare unused mono camera!

Hmm,... sky is clear or not, irrespective of an instrument setup used. Mono camera collets the data with better statistics (call it faster) and one can change filters with any frequency appropriate. So , in a given clear sky window, one could collect better data with mono camera. Yes , it does take an EFW and motorized focuser, but that is more or less standard these days .

SemiPro

IOTD Staff

Sep 3, 2023

There is no denying that monochrome is supreme in terms of quality and data acquisition efficiency. It's not even a contest for narrowband data; there is no way you could ever pay me to try and collect narrowband data with a OSC again because of how inefficient it is. When it comes to broadband data, I think the gap closes a lot with these new sensors.

I would probably go with mono if I could only have one camera. The narrowband opportunities are too much to pass up.

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Jonathan Saine

Sep 3, 2023

I learned pretty early on in my astrophography journey that a monochrome camera is far superior. Acquisition takes longer but that's a small price to pay for results that I am unquestionably more pleased with. Personally I would never go back to OSC, full frame or not. For what it's worth, I have Bortle 5 skies where I image from. Good luck.

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George Yendrey

Sep 3, 2023

Brian Boyle:
Mostly mono for me too. If you are shooting mostly galaxies, then there is a "convenience" argument for OSC. But then you probably wouldn't need FF OSC.
If shooting most nebulae with an OSC, you may get tired of red. I did, and switched from the 2400MC [great camera] to a 6200MM [another great camera] - at least on my RC8 scope.

I still shoot wide-field with the 2400MC using my Nikon 200mm lens, but I haven't gone back to OSC on my telescope.

CS Brian

I’ve still got my 2600MC in a large ziploc bag with its filter wheel, thinking I might use it for some “quick” imaging. Its been 18 months since I went mono with the 2600MM and the MC version has never left its storage bag. I guess I need to sell it and admit to myself I’m never going back to an OSC. 😎

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George Yendrey

Sep 3, 2023

There is no denying that monochrome is supreme in terms of quality and data acquisition efficiency. It's not even a contest for narrowband data; there is no way you could ever pay me to try and collect narrowband data with a OSC again because of how inefficient it is. When it comes to broadband data, I think the gap closes a lot with these new sensors.

I would probably go with mono if I could only have one camera. The narrowband opportunities are too much to pass up.

I have both the 2600MC and the 2600MM. The MC version in broad band (L-Pro filter for light pollution/Bortle 5) is quite good. Until you compare it directly to an image of the same target shot in LRGB with 2600MM. The OSC image is still not bad, and a casual viewer might not notice a difference. But the difference in fine detail becomes apparent on close examination. The reason is simple math and physics - the APS-C raw image on the OSC is a composite of lower resolution images (much lower) due to the Bayer mask required to create a color image. The mono images are full sensor images for EVERY filter image shot.

In post processing , I’ve found that the mono frames have a lot less noise than their OSC counterparts and obviously none of the color mottling noise that are present in OSC. Both of those make the mono post processing easier and less prone the nouse reduction artifacts that can be created if a person gets a little too aggressive.

YMMV
CS
Clayton

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Miran Brezočnik

Sep 3, 2023

Hello,
I have both cameras equipped with the Sony IMX571 sensor, one being an OSC (One Shot Color) camera and the other a monochrome camera, namely the QHY268C and QHY268M. Both cameras use the same sensors as the ZWO ASI2600M. I purchased both of them last year. In my specific case, acquiring the OSC camera has proven to be a poor investment since I haven't taken any images with it since I acquired the monochrome camera. However, I won't be selling the OSC camera just yet because it comes in handy for tasks such as capturing comet images and certain galaxies. The monochrome camera is superior and allows for higher-quality images. Processing images with the monochrome camera does require a bit more time, but it provides the user with greater creativity, and subframes taken under identical conditions are of higher quality. With the OSC camera, the user is limited to a relatively small selection of targets, especially when shooting from light-polluted areas. While dual-band filters can be used with the OSC camera, the final resolution and image quality are higher when using the monochrome camera.
Best,
Miran

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Apsc mono vs fullframe osc