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RASA 8" and 11" optimal CMOS cameras

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#1 aacc66

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Posted 07 July 2019 - 09:48 PM

I understand that the RASA 8" has an image circle ~22 mm diameter, and the RASA 11" is ~43 mm.   Using an CCD pixel size calculator, a 2.4 micron pixel is quite optimal for the RASA 8" and 3.4 micron pixel for the RASA 11".

 

Can any one suggest CMOS astrophotography cameras that are optimized for these two OTAs? or if there is an actual thread, provide a link?

 

Thanks,

 

Alvaro



#2 bobzeq25

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Posted 07 July 2019 - 10:37 PM

I use a 183color with my C8 RASA.  The 183's tiny pixels match up well with the 8 RASA's focal length and speed.  Here's first light.  The brighter stars color is not good because I overexposed the subs.

 

https://www.astrobin...413196/?nc=user


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#3 aacc66

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Posted 07 July 2019 - 10:40 PM

Bob,

 

Yes, the 183 sony chip seems to be a candidate.  Right now the only candidate, which makes me wonder if there are more options.

 

Thanks for the reply.

 

Alvaro

I use a 183color with my C8 RASA.  The 183's tiny pixels match up well with the 8 RASA's focal length and speed.  Here's first light.  The brighter stars color is not good because I overexposed the subs.

 

https://www.astrobin...413196/?nc=user



#4 bobzeq25

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Posted 07 July 2019 - 11:32 PM

Bob,

 

Yes, the 183 sony chip seems to be a candidate.  Right now the only candidate, which makes me wonder if there are more options.

 

Thanks for the reply.

 

Alvaro

Sure.  An 071, with its big chip, would do some fine really wide angle images.  The image scale is not a killer, although, if you have light pollution like mine, exposures would be even shorter, subs more numerous.  I built a new PC with a Threadripper, in anticipation.



#5 lucutes

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Posted 08 July 2019 - 01:00 PM

I understand that the RASA 8" has an image circle ~22 mm diameter, and the RASA 11" is ~43 mm.   Using an CCD pixel size calculator, a 2.4 micron pixel is quite optimal for the RASA 8" and 3.4 micron pixel for the RASA 11".

 

Can any one suggest CMOS astrophotography cameras that are optimized for these two OTAs? or if there is an actual thread, provide a link?

 

Thanks,

 

Alvaro

QHY has two cameras with APS-C image circles that I think would be killer for this scope. The current QHY247C 3.7 um pixels and the upcoming QHY268C also at around 3.6um pixels but at 16 bit.


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#6 aacc66

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Posted 08 July 2019 - 09:35 PM

the ZWO 071 ($1480) chip and the QHY247C ($2000) seems to be good priced and appropriate to take advantage of the RASA 8" image circle.  The RASA 11" with a full chip size seems to be at a disadvantage of not having a decently priced astrophotography camera, the only ones I saw where the QHY367C (at $4400) and the QHY29 (at a Wooping $7500).  It seems that the RASA is better served by a DSLR, like a D810, even if the camera sticks out a lot.

 

Alvaro

Sure.  An 071, with its big chip, would do some fine really wide angle images.  The image scale is not a killer, although, if you have light pollution like mine, exposures would be even shorter, subs more numerous.  I built a new PC with a Threadripper, in anticipation.

QHY has two cameras with APS-C image circles that I think would be killer for this scope. The current QHY247C 3.7 um pixels and the upcoming QHY268C also at around 3.6um pixels but at 16 bit.



#7 Phil Cowell

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Posted 09 July 2019 - 07:29 AM

ATIK 4120EX kicks tail. It’s narrower which is a huge plus for the RASA 8”. One well worth looking at.



#8 bobzeq25

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Posted 09 July 2019 - 10:01 AM

ATIK 4120EX kicks tail. It’s narrower which is a huge plus for the RASA 8”. One well worth looking at.

Most of the cameras recommended don't overlap the central obstruction of the C8.  As long as they don't do that, I don't think there's much of an advantage.

 

A DSLR would be a different story.


Edited by bobzeq25, 09 July 2019 - 10:02 AM.


#9 carolinaskies

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Posted 09 July 2019 - 10:22 AM

From what i've read the smaller mirrorless consumer cameras are well suited to the 8" RASA with their small size and 4/3 and APS-C sensors. Considering they can be used to take plenty of exposures without cabling it makes the setup rather appealing.  


 



#10 Phil Cowell

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Posted 09 July 2019 - 11:20 AM

Most of the cameras recommended don't overlap the central obstruction of the C8.  As long as they don't do that, I don't think there's much of an advantage.

 

A DSLR would be a different story.

The ATIK 4120EX is also a good camera for the RASA smile.gif


Edited by Phil Cowell, 09 July 2019 - 11:21 AM.

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#11 Phil Cowell

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Posted 09 July 2019 - 11:22 AM

From what i've read the smaller mirrorless consumer cameras are well suited to the 8" RASA with their small size and 4/3 and APS-C sensors. Considering they can be used to take plenty of exposures without cabling it makes the setup rather appealing.  


 

You might need a power cable to the camera during a night with multiple targets.



#12 aacc66

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Posted 09 July 2019 - 11:54 PM

Most of the cameras recommended don't overlap the central obstruction of the C8.  As long as they don't do that, I don't think there's much of an advantage.

 

A DSLR would be a different story.

Bob,

 

Could you elaborate more on your comment? I think I am reading contradicting statements in it, but maybe I am being a bit slow.

 

Alvaro



#13 aacc66

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Posted 10 July 2019 - 12:09 AM

Does anyone have a RASA 11"? are they using a DSLR or an actual astrophotography camera?

Just curious.

 

Just to give a bit of background, I am saving to get a fast OTA, and right now I am considering a 100mm Apochromatic, F7 or even F5.

 

But the idea of a RASA 8" or even a RASA 11" at a ~F/2 is quite appealing.  The thing with a RASA is that it is definitively an AP OTA; no option for observing with it, so a camera is really important and it needs to be procured at the same time with the RASA, and that means saving for a longer time.  With the Apochromatic, I can buy it without having to get an ideal camera right away.

 

Alvaro



#14 bobzeq25

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Posted 10 July 2019 - 12:42 AM

Bob,

 

Could you elaborate more on your comment? I think I am reading contradicting statements in it, but maybe I am being a bit slow.

 

Alvaro

Someone suggested a 4120 has a major advantage because it's small.  I think that, provided a camera fits within the 93mm central obstruction, smaller is not a big advantage.



#15 Phil Cowell

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Posted 10 July 2019 - 09:37 PM

Someone suggested a 4120 has a major advantage because it's small.  I think that, provided a camera fits within the 93mm central obstruction, smaller is not a big advantage.

That was me but it has a great resolution and sensitivity too. The thin camera makes cabling less of a hassle, as you have a space buffer within the central obstruction diameter.




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