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Contemplating move from DSLR to cooled astro-cam

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#1 southerndandy

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Posted 27 January 2021 - 03:56 PM

Afternoon, everyone.  As it says, I've been using an unmodified Canon T6 for a couple of years now and I've been looking at making the move to a cooled astro-cam.  The biggest reason for the move is noise and dark frames.  My T6 is pretty noisy, and we all know the conversation about darks with a DSLR.  The idea of a darks library is pretty tempting. 

 

All that said, I currently use an Orion ED80 with it's reducer/corrector which makes it 510mm and f/6.3.  That with the T6 gives me an image scale of 1.7 arcsec/pixel.  I've been looking at the ZWO ASI533 MC Pro, the ZWO ASI183 MC Pro, and the ZWO ASI294 MC Pro.  All cooled OSC, I really don't feel I could handle mono/filters right now.  Not just the equipment, but the processing as I'm still building skills in processing.  I use NINA and PHD2, and it all rides on a Sirius mount if any of that matters.   

 

The 533 would give me an image scale of 1.52 arcsec/pixel and has a 50k full well, but I don't know how I feel about the square sensor and the FOV it gives.  

 

The 183 would give me .97 acrsec/pixel and only has a 15k full well.  I've heard that the 183 likes faster scopes, and at 6.3 mine's not really considered fast.

 

The 294 would give me 1.87 arcsec/pixel and has a 63k full well which is a lot more then my DSLR is (i'm pretty sure).  The pixel size and scale and FOV would be closest to what I have currently with my DSLR.

 

I've played around on telescopius and stellarium with the different FOV's and settings for the different cameras.  I initially thought to go for the 183, but now I'm leaning towards the 294, mainly because of the full well and the FOV.  Am I thinking about this all correctly?  Does anyone have experience with using the ED80 (or similar) with one of these cameras?  I'm not necessarily locked into ZWO products, but these seem to be more ubiquitous than some others.  Any thoughts or insight is appreciated.  

 

Also, if anyone has a book or resource that covers imaging with a cooled astro-cam I'd be interested in it as everything I've got currently revolves around DSLR imaging.  (specifically I'm looking for info on working with gain, offset, and cooling.)     



#2 MikiSJ

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Posted 27 January 2021 - 04:24 PM

I  have been following a lot of threads similar to southerndandy's specifically regarding mono versus OSC. Southerdandy is concerned about filters and mono. I currently shoot with an ASI294MC-Pro but wish I had chosen the mono/filter route.

 

Question I have, and hopefully it will help southerndandy also, but would there be any sense in going with a mono camera and one of the newer tri- or quad- filters. . The difference between a color ASI294 and a mono ASI294 is the Bayer filter layer. Removing the Bayer filter gets the 294 sensor to an unbinned 2.3µm size. This might be too small for some OTA, but then the pixels can be binned back to 4.63µm and larger.

 

I realize there might not be much of a cost difference, but just thinking


Edited by MikiSJ, 27 January 2021 - 04:25 PM.


#3 Wow!

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Posted 27 January 2021 - 08:26 PM

I wouldn't touch mono, as a beginner (my own opinion) because it's too much work.

Not just the setup, the software, the "more things to go wrong", but the editing as well.

 

OSC is my present and future with a narrowband filter when needed.

 

To the OP, the 294 seems like the camera to get. Higher full well is a good thing



#4 const

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Posted 27 January 2021 - 09:06 PM

Definitely do it. Moving from D7500 to ASI294MC was a big jump for me. They have similar sized pixels and other specs. Even full well depth is comparable on paper. Yet, with cooled camera it is much easier to pull more data in darkest areas, thanks to precise dark calibration.



#5 imtl

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Posted 27 January 2021 - 09:22 PM

I  have been following a lot of threads similar to southerndandy's specifically regarding mono versus OSC. Southerdandy is concerned about filters and mono. I currently shoot with an ASI294MC-Pro but wish I had chosen the mono/filter route.

 

Question I have, and hopefully it will help southerndandy also, but would there be any sense in going with a mono camera and one of the newer tri- or quad- filters. . The difference between a color ASI294 and a mono ASI294 is the Bayer filter layer. Removing the Bayer filter gets the 294 sensor to an unbinned 2.3µm size. This might be too small for some OTA, but then the pixels can be binned back to 4.63µm and larger.

 

I realize there might not be much of a cost difference, but just thinking

There is no sense in using a mono camera with one of the duo/tri/quad filters. These filters have multiple bandpasses at different wavelength and you're going to get all of those mixed together in a mono sensor. The big advantage in mono (besides other things) is the ability to capture data of different wavelengths separately for maximum control of the signal and final image. 


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#6 Alex McConahay

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Posted 28 January 2021 - 11:45 AM

>>>>>>>All cooled OSC, I really don't feel I could handle mono/filters right now.  Not just the equipment, but the processing as I'm still building skills in processing.

 

In my mind, the purchase of a camera is a long term thing. Learning the little steps it takes to process mono/filters is a short term thing. The hard part of any processing is controlling the noise, and stretching the data so that the detail shows up. That is, I believe, a lot easier in mono/filter than in OSC. THe added steps (separate images, flats, calibration groups the LRGB combine) are relatively easy to learn, and largely automated with most software. Otherwise, the process of controlling the noise and stretching (the hard parts of processing) is the same whether OSC or mono/filters EXCEPT.... The LRGB data is generally higher quality data in the first place, making the noise reduction and stretching easier. You simply have a higher top end with mono/filter than with OSC, and the extra work is largely automated, and relatively easy anyway. 

 

I would not by a OSC camera because it is a better "learner" when the extra stuff I had to learn to get much better pictures was so easy to learn. And besides......let's say you buy the OSC, and then in a few months decide to try the relatively easy bump up into mono/filter----you have kinda wasted money on the learner. 

 

If I were you (except with my experience), I would buy the mono camera, and use it till I felt like adding the filter wheel and filters  and going full LRGB. And then add Narrowband later.

 

Alex


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#7 Rasfahan

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Posted 29 January 2021 - 12:47 PM

All these cameras will work well with your scope, I wouldn't sweat the sampling. You will not image small galaxies and PN with your scope, anyway. The IMX183 might get you slightly more detail than the IMX294 (but your small aperture will limit the benefit) which will gather data a bit faster (but you can just downsample the ASI183 in post for a similar result). The data I have seen from the IMX533 chips is cleaner than the two others, but the ASI183 data is very clean, too, while my 294 produces a bit noisier subs. The stacks will work well for any of these cameras. At 80mm f/6 on a Sirius full well capacity is probably not your concern, you will be limited by your guiding. If you want to go OSC and want a 4/3" FOV, I would say the ASI294 is the way to go. If you want a smaller FOV, I feel the 533 might be slightly easier to work with than the ASI183 because of no amp glow. On the other hand, with the ASI183 you will know at once when you made a mistake in calibration because the amp glow will show up - if you do everything correctly, it disappears completely in the calibrated subs and the final stack.

 

I am not sure why you want OSC, though. I agree with Alex that mono cameras produce superior data. And since you focus on one channel at a time, you can treat each one as it needs and combine afterwards, which makes it easier to produce nice images. If you do not have very dark skies, narrowband is a game changer and will allow you to pull out far more detail from nebula than with OSC (You cannot well get a separate S2 channel in OSC, and you cannot focus on just O3 for those fainter O3 parts). Under more light pollution the acquisition of L really helps to increase the efficiency of light gathering for RGB data. Contrary to what some say, this much reduces the acquisition time needed. From my experience, OSC data is not easier to work with. I often have to separate channels anyway (and I always need to extract a luminance layer).  I got my OSC for traveling to get a scope, star adventurer and imaging train all into an on board case.

 

I started with a mono camera with a full 7-position filterwheel. The data I got was much superior and far easier to work with than that from my DSLR, it was a game changer. 

 

If you are on a constrained budget, you might also consider an ASI1600. The chip is deemed obsolete, and production has ceased, but you can still produce very nice images with it. There are still some new ones sold, usually for a good price. Also there is a huge amount of expertise with this chip in this community. It is the camera I started with, and all question I had (and many I never thought to ask) were easily answered by an internet search. The advantages of the ASI294 are minor in comparison, and the money saved could go to some filters and a filterwheel. I am not sure if the new mono ASI294 is ready for prime time yet, there were some teething problems (I am sure the QHY294 is not). 


Edited by Rasfahan, 29 January 2021 - 12:48 PM.


#8 pedxing

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Posted 29 January 2021 - 02:37 PM

I'll side with the recommendations for going mono, I think Alex lays it out pretty well.

 

The extra processing when using mono/filters is really just pre-processing, which isn't complicated or really much different than pre-processing OSC other than working on four batches of subs vs having a single debayer step. But once you've done the pre-processing you end up with an RGB image just like with OSC. Except that every pixel is used for every color - an important distinction.

 

Early in my journey, I made the choice to purchase a cooled OSC as my first cooled camera. I think I used it for three or four images before purchasing a mono camera. It's been gathering dust ever since (several years), although I've recently come up with a compelling use case for it and am in the process of getting it back up and running. But I would have been better off just going mono to start with, and at this point I could get a much better OSC camera for a lot less money than I originally spent, now that I have a good reason to use one.

 

As an aside, the reason I now have a use case for the OSC is that I have access to a much darker site and very limited time to gather color subs. And I already have a mono camera that I can use for L to combine the RGB from the OSC with.




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