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Moving from DSLR to OCD CMOS

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#1 adversefx

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Posted 19 February 2020 - 02:21 PM

Hey folks,

 

I've been using a modified DSLR for the past year, and I feel like I'm ready for a cooled CMOS. I've narrowed my search down to 3 options: ASI294MC Pro, ASI533MC Pro, and ASI183MC Pro. I currently own a Zenithstar 61 and an AT65EDQ. I am hoping that you can advise which of these 3 cameras would be best suited to use with both scopes. Seeing conditions where I live are typically average to below average on nights that are clear enough for imaging, but occasionally are above average. I've used the CCD suitability calculator on the Astronomy Tools website, but it seems like all 3 cameras favor either one scope or the other. I'm hoping that you can please give me some advice on which camera would suit me the best. 

 

Thanks!



#2 OhmEye

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Posted 19 February 2020 - 02:40 PM

The ASI183 has the smallest pixels of the 3 cameras you list, and is the only one that isn't undersampled with a Z61 on the calculator for OK seeing conditions. The ASI533 has an ok pixel size for the AT65 but is undersampled with the Z61. The ASI294 is undersampled with both, although the 2 scopes are close enough in focal length that all these differences depend a lot on seeing conditions. I had a similar decision and chose the ASI183.



#3 DrGomer

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Posted 19 February 2020 - 03:09 PM

The 533 does have an advantage in it is the easiest to work with. The lack of glow means I can practically get away with no dark/bias calibration and just dither instead. 
And on the dither note, if you have enough dithered subs, you can drizzle integrate and recover under sampling (just takes a fair bit longer processing time). 

If you stay with very short focal length scopes like you list, the 183 will be great, but it won't be long before you start oversampling if  you move to longer focal lengths.  


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#4 OhmEye

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Posted 19 February 2020 - 04:32 PM

I agree the 533 is attractive, and if it won't be too undersampled with a Z61 for the seeing conditions it's an excellent choice. It's in the sweet spot for image scale with 80-130mm refractors. If seeing is better than 2" though it's more undersampled than I would like for under a Z61 but not terrible.

 

For OK to good seeing, I agree with the AT calculator that the 183 isn't oversampled under 800mm, and to me it's a good choice if the goal is to use with both 360mm and 715mm focal lengths. For just 400-800mm FL, I think the 533 is an outstanding choice. If that was my priority and I was ok with undersampling that amount or my seeing conditions were appropriate for it I would be fine with using a 533 on a Z61 to save cost for another camera. In other words, I would compromise in favor of my best scope or planned future scope.



#5 adversefx

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Posted 19 February 2020 - 05:17 PM

Thank you both for the replies. I'm definitely starting to lean towards the 533. The AT65EQ has become my primary scope lately and I don't plan to go any wider than the Z61 in the future. Plus, if I do go with the 533, the under-sampling with the Z61 isn't too severe and actually a little less than what I have now with my D5300. I already drizzle when using that combo, so I'm fine with the extra integration time. 




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