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RASA 11- what is the ideal camera pixel size?

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#1 pyrasanth

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Posted 13 April 2021 - 05:06 PM

I'm trying to decide what the optimal pixel size for the RASA 11 would be. The smallest pixel size I can find is the 2.4 um ZWO ASI183MM or similar sensor. However the spot size for the instrument is 4-4.5 um so I wondered if this will have a bearing negating the smaller pixel size or is that more about the spread of the light which would span 2 pixels (under ideal conditions) for this camera. I think it would be quite rare to realiase the true potential of the RASA under my poor skies but one can always hope. The math says about 0.8 arc secs per pixel at 620 mm focal length on a 1x1 bin.

 

It might even be worth binning the ASI183 to 2x2 to get 1.6 arc secs per pixel.

 

I could carry on with the ASI6200 with its 3.7 or so sensor pixel size however that mostly lives on the C14 and removing the camera to go to the RASA normally means a new set of flats need to be created when it is put back on the C14.

 

I've ordered the ZWO ASI183MM pro for the RASA to have a play around however the jury is out as to what would be the optimal sensor pixel size- let me know your thoughts.

 

I think I will get a good field with a smaller sensor- I crop most targets when I use the ASI6200 on the RASA so I don't think it will be too much of an impediment- I can always switch back to the ASI6200 for wider field targets.

 

Let me know your thoughts-please.


Edited by pyrasanth, 13 April 2021 - 05:26 PM.


#2 Rasfahan

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Posted 14 April 2021 - 01:02 AM

Since you have your RASA well enough handled that the full-frame 6200 works, I am sure you will have great results with the 183. It is far less troublesome for me than even a M4/3“ chip. I find no discernible difference in the star shapes - when they look good on the ASI1600, they are fine with the smaller pixels, too. The images from my Astrobin are all without proper collimation due to the bad winter. I have another scope on the mount now for galaxy season.
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#3 calypsob

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Posted 14 April 2021 - 07:50 AM

My vote would be to undersample and role with an asi 2400 if you can swing it in the budget.

That sensor would build an enormous snr very quickly on a rasa system.


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#4 pyrasanth

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Posted 14 April 2021 - 02:06 PM

My vote would be to undersample and role with an asi 2400 if you can swing it in the budget.

That sensor would build an enormous snr very quickly on a rasa system.

I'm testing the 183MM pro now and I will see how that performs- I don't really need a large sensoe for this phase of my experiments. The 2400 is really nice but as I have the ASI6200 I could bin that 2x2 and probably get a similar result-I think it can reach a point where the expenditure becomes quite punitive however I appreciate the food for future thought.



#5 pyrasanth

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Posted 14 April 2021 - 03:47 PM

I'm testing the ASI183MM Pro on a 2x2 bin. 1.6 arc secs per pixel for a 60 second sub on the RASA is superb. The images have loads of data and being a very much smaller sensor the collimation and field flatness is pretty much spot on. This field size also correlates very well with the required upscaling for the C14- I think i can expect good work from this combination. I'm testing with some L frames currently but I have a full set of the high speed Baader narrow band filters so that will be good to test as well.

 

I will keep you posted- Starlink sats continue to ruin many subsmad.gif

 

I've posted the CCD inspector result from 30 subs from the RASA V2

 

183TILT.JPG


Edited by pyrasanth, 14 April 2021 - 04:21 PM.


#6 Huangdi

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Posted 14 April 2021 - 04:08 PM

I'm definitely looking to upgrade my 8" to an 11" when I get the chance...and the 294MM is basically the perfect sensor for it. 

 

I hate the thought of having such a large imaging circle and not using it with my 183, but the 294 chip is basically made for that scope.

 

You can use a ROI and shoot 20MP or less in 1x1 bin mode for small objects and take the full sensor at 2x2 bin for larger objects.


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