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  #1  
Old 21-06-2018, 03:36 PM
brenchen
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Help me choose: ZWO ASI1600MC Pro or ASI183C Pro?

Thanks to everyone that has helped me in the last post about ZWO vs Altair so I can move forward in my quest to search for my ideal astro camera!

I am now solely focusing on ZWO camera due to accessibility and user feedback. I intend to image DSO on an HEQ5 and a SW Evostar 80ED (600mm). Most of the imaging will be done near a darksite (little bit of light pollution, but not inner suburbs. And I've narrowed it down to ASI1600MC Pro [Edit: ASI294MC Pro seems to be better instead of the 1600MC Pro] and ASI183C Pro.

I like the 4/3" sensor on the 294 and larger pixel size for better image quality, as well as the higher suitability to DS imaging. However, astronomy.tools suggests the ASI183C (1" sensor) is a better pick for clarity and details (or did I mistaken what it said?).

So my question is, what is more important to consider in a camera between the two I mentioned? What should be the determining factor to choose one over the other?

Thanks in advance

Last edited by brenchen; 21-06-2018 at 09:37 PM. Reason: Realised an extension of the 1600 to be the 294
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  #2  
Old 21-06-2018, 04:14 PM
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Atmos (Colin)
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I’d probably go the 1600. It has a slightly wider field, lower read noise for narrowband and the pixel size of the 183 is approaching diffraction of your 80mm so the larger pixels of the 1600 and likely more forgiving.
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  #3  
Old 21-06-2018, 04:15 PM
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Nikolas (Nik)
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Have a look at images taken with both and decide for yourself, not many of us here can afford both cameras and in reality the people who offer you advice either don't have either of them and only go by what they read OR they have one camera over the other and would not be able to provide a decision either way, then there are those that suggest going mono with filter wheels and filters because they give out a better image yadda yadda and don't actually answer your question.
Hope my non advice is good advice
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  #4  
Old 21-06-2018, 04:17 PM
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Quote:
Originally Posted by Atmos View Post
I’d probably go the 1600. It has a slightly wider field, lower read noise for narrowband and the pixel size of the 183 is approaching diffraction of your 80mm so the larger pixels of the 1600 and likely more forgiving.
Stupid question, what is the effect of diffraction if you use this in a larger scope? What does that mean exactly?
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  #5  
Old 21-06-2018, 05:39 PM
glend (Glen)
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Read Jon Rista's excellent beta test thread on the 183 on Cloudy Nights forum. Jon has been doing user testing of newly released ASI cameras for Sam (ZWO). It is a nice camera but a 1600 killer it is not.

That said, you might be happy with either..
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  #6  
Old 21-06-2018, 07:12 PM
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Originally Posted by Nikolas View Post
Stupid question, what is the effect of diffraction if you use this in a larger scope? What does that mean exactly?
Diffraction can be roughly calculated at 4.56/aperture (inches).
4.56/3.15= 1.45” this is an 80mm diffraction limit.

The 1600 is at 1.3”/pixel while the 183 is at 0.83”/pixel. From an optical stand point, you’re not really loosing much with the 1600 against the 183.

When you get into larger apertures seeing conditions become larger than diffraction and you also tend to get more into faster focal ratios (8” F/4-5 Newtonian for instance) which mean that you’re diffraction limit and imaging scale are further apart.
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  #7  
Old 21-06-2018, 07:18 PM
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"Diffraction can be roughly calculated at 4.56/aperture (inches).
4.56/3.15= 1.45” this is an 80mm diffraction limit.

The 1600 is at 1.3”/pixel while the 183 is at 0.83”/pixel. From an optical stand point, you’re not really loosing much with the 1600 against the 183.

When you get into larger apertures seeing conditions become larger than diffraction and you also tend to get more into faster focal ratios (8” F/4-5 Newtonian for instance) which mean that you’re diffraction limit and imaging scale are further apart."




Um that means nothing to me but numbers and gobbledygook (no offense )Can you explain diffraction limits in laymans terms?
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  #8  
Old 21-06-2018, 08:33 PM
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billdan (Bill)
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Nik,

Diffraction limited optics are a way of expressing the telescopes resolution, i.e. the smallest dot of light it can reveal in arcsecs.
So if you see a telescope advertised as diffraction limited it means that it complies with the resolution formula of 4.56 / aperture (inches).

So your 80mm ED refractor has a resolution of 1.45 arcsecs.

Nyquest theory says we should sample the smallest resolution by 2x or for your ED80 use a chip with that can sample at 0.7 arcsecs per pixel.

But as most of us are seeing limited where the smallest resolution gets blurred out by the seeing. We only need to sample for 2 arcsecs (good seeing) or up to 4 arcsecs (bad seeing).
So a chip which can provide 1 arcsec/pixel sampling is fine for us amateurs.

arcsec / pixel = pix size(microns) x 206.3 / focal length(mm)

Hope this helps
Bill
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  #9  
Old 21-06-2018, 09:05 PM
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Sort of Bill I seem to be getting it
Does that mean that the 183 would be blurry or not as sharp in my c9.25 even with a .63 reducer but be pin sharp in my ed80??

Last edited by Nikolas; 21-06-2018 at 09:16 PM.
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  #10  
Old 21-06-2018, 09:18 PM
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The diffraction limit is a telescopes ability to fully resolve to point light sources. A good example of this can be with splitting double stars where an 80mm refractor will not be able to cleanly split two stars with less than a 1.45" separation. With a separation of 1.3", two stars could be seen as a misshapen star and the centroids will be separate but the diffraction rings will not be split.

A 130mm refractor has a diffraction limit of 0.89". Your C9.25 has a diffraction limit of 0.5". This is all a function of aperture. Now with the 183 you're getting a pixel scale of 0.33"/pixel but with the 1600 you're imaging at 0.53"/pixel. At this scale you're biggest problem is your seeing conditions more so than whether you're near your C9.25 diffraction limit.

This 1600 is better for the C9.25 as you are at a better imaging scale and the sensor is a big larger.
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  #11  
Old 21-06-2018, 09:43 PM
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So far what I've gathered is 1600MC and 183C are highly comparable, but 183C gives me better clarity because the pixel sizes are smaller?

I just learnt about the 294MC Pro which seems to be a continuation from the 1600MC. Again it will still be comparable to the 183C. But since I prefer the larger sensor, I should probably just go for that over the 183C rather than adding glass in front of the sensor trying to get greater FOV?
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  #12  
Old 21-06-2018, 10:00 PM
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Quote:
Originally Posted by Atmos View Post
The diffraction limit is a telescopes ability to fully resolve to point light sources. A good example of this can be with splitting double stars where an 80mm refractor will not be able to cleanly split two stars with less than a 1.45" separation. With a separation of 1.3", two stars could be seen as a misshapen star and the centroids will be separate but the diffraction rings will not be split.

A 130mm refractor has a diffraction limit of 0.89". Your C9.25 has a diffraction limit of 0.5". This is all a function of aperture. Now with the 183 you're getting a pixel scale of 0.33"/pixel but with the 1600 you're imaging at 0.53"/pixel. At this scale you're biggest problem is your seeing conditions more so than whether you're near your C9.25 diffraction limit.

This 1600 is better for the C9.25 as you are at a better imaging scale and the sensor is a big larger.



Thanks for that
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  #13  
Old 21-06-2018, 10:53 PM
glend (Glen)
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Quote:
Originally Posted by brenchen View Post
So far what I've gathered is 1600MC and 183C are highly comparable, but 183C gives me better clarity because the pixel sizes are smaller?

I just learnt about the 294MC Pro which seems to be a continuation from the 1600MC. Again it will still be comparable to the 183C. But since I prefer the larger sensor, I should probably just go for that over the 183C rather than adding glass in front of the sensor trying to get greater FOV?
I would stay away from the 294MC, early adopters are reporting problems with calibration and cooling, and even Sam from ZWO is now positioning it as an EAA camera. The sensor architecture does not allow for even cooling of the rear of the chip, hence colour artifacts are appearing due to uneven strata cooling. It also has pretty bad AMP glow at longer exposure times.

You can read some of the concerns with the 294 on this ZWO support forum thread:
https://bbs.astronomy-imaging-camera...hp?f=21&t=8007


The 1600 is a well known camera with a good reputation and no vices.
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  #14  
Old 22-06-2018, 06:25 AM
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theodog (Jeff)
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Quote:
Originally Posted by Atmos View Post
The diffraction limit is a telescopes ability to fully resolve to point light sources.
This is just resolution. Always has been the resolution and always will be the resolution.

The 'diffraction limit' is rubbish. rarely reached if ever.

Why give it another name.

I have been eyeing off the 1600.

Last edited by theodog; 22-06-2018 at 06:58 AM.
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  #15  
Old 22-06-2018, 07:33 AM
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Quote:
Originally Posted by glend View Post
I would stay away from the 294MC, early adopters are reporting problems with calibration and cooling, and even Sam from ZWO is now positioning it as an EAA camera. The sensor architecture does not allow for even cooling of the rear of the chip, hence colour artifacts are appearing due to uneven strata cooling. It also has pretty bad AMP glow at longer exposure times.

You can read some of the concerns with the 294 on this ZWO support forum thread:
https://bbs.astronomy-imaging-camera...hp?f=21&t=8007
...
This is indeed VERY concerning. I'm glad I asked, and thanks for the info and the link!


Quote:
Originally Posted by glend View Post
... The 1600 is a well known camera with a good reputation and no vices.

I know the 1600MM (mono) is great, does this same reputation also extends to the color OSC version?

Last edited by brenchen; 22-06-2018 at 08:13 AM.
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  #16  
Old 22-06-2018, 07:20 PM
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If you have been using a DSLR before as an astro camera you are not gaining much going to a 1600mc-c. That was the final thing that convinced me to go 1600mm-c, the better resolution. Sure it's a whole new learning curve but I needed to be able to make a significant improvement to justify the cost. So far I have not regretted it one bit. The camera has been awesome and Sharp cap been easy enough to learn but clever enough to do everything I have thrown at it. And I am still learning.
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  #17  
Old 22-06-2018, 08:28 PM
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If you have been using a DSLR before as an astro camera you are not gaining much going to a 1600mc-c. That was the final thing that convinced me to go 1600mm-c, the better resolution. Sure it's a whole new learning curve but I needed to be able to make a significant improvement to justify the cost. So far I have not regretted it one bit. The camera has been awesome and Sharp cap been easy enough to learn but clever enough to do everything I have thrown at it. And I am still learning.
Where do you image and how long do you capture for for each channel?

The problem for me is I have ONE night (as in sunset to midnight) a month at a dark site to really do my imaging, so I don't have the time to devote to mono. I know 1600MM is a very well respected mono camera, that's why I was hoping to understand which is its equivalent in the realm of coloured cameras.

Last edited by brenchen; 22-06-2018 at 08:59 PM.
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  #18  
Old 23-06-2018, 05:33 AM
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I have a tin shed Observatory in the back yard.

OK, in that case the 1600MC-c sounds the better option. It has way more control within the software, is a lot 'faster' than a DSLR and being cooled, far less noise. That was my other option for ease of use and speed but with the Ob and now being retired I have time to play.

You will need to manage more power for the cooler but I find once it has reached operating temp ( I run at 0*) it is using minimal current, maybe 100-200 milliamps.

You will love the software options the software and camera gives you. I often use the ROI box to select solar areas of interest rather than run full frame or having to readjust the scope alignment. Needs a powered hub and good USB cables or keep them short.
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Old 25-06-2018, 08:59 AM
brenchen
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I have a tin shed Observatory in the back yard.

OK, in that case the 1600MC-c sounds the better option. It has way more control within the software, is a lot 'faster' than a DSLR and being cooled, far less noise. That was my other option for ease of use and speed but with the Ob and now being retired I have time to play.

You will need to manage more power for the cooler but I find once it has reached operating temp ( I run at 0*) it is using minimal current, maybe 100-200 milliamps.

You will love the software options the software and camera gives you. I often use the ROI box to select solar areas of interest rather than run full frame or having to readjust the scope alignment. Needs a powered hub and good USB cables or keep them short.

After weighing up all the options, and speaking to the finance department, I was encouraged to get the mono. So mono ordered with the 8 slot wheel now, can't wait!


What software do you recommend? At the moment I'm inclining towards SGPro, but find it extremely difficult to configure/use. Maybe it'll make more sense to me when I get everything rigged up and connected - hopefully anyway.
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  #20  
Old 26-06-2018, 03:56 AM
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SharpCap 3.1 is much easier to use. I tried SGP but found it confusing and rather unintuitive. Sharpcap is free and there is a 10 pound annual fee to upgrade to Pro which I think gives sequencing control. I haven't bothered with that as the Ob is in the backyard and I just use Team Viewer to remote to the PC in the Ob from inside to control the software and guiding.

Give it a try, it's free so nothing to lose. Uninstall if you don't like it.

https://www.sharpcap.co.uk/

ZWO have their own lightweight version, ASICAP but it's a lot more limited.
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