How to select OTA for DSO? - Forums

Topic starter

Mar 10, 2023

Hi,

I have been using the following OTAs till now,

1] Sharpstar 60ED F5.5 APO Refractor (Wide field)
2] Sky-watcher 130PDS F5 Newtonian (Open clusters, nebulae)
3] GSO 6 inch RC F9 Ritchey-Chretien (Globular clusters, Galaxies, Planetary nebulae)

I know all 3 have different focal lengths & FOV so used for different purposes.

Cameras ZWO 1600MM-Pro, Canon EOS 700D (Modified)

Mount iOptron iEQ45-Pro (45 pounds capacity)

My question is I am imaging from the City sky.

In order to image very faint targets like Galaxies, tiny planetary nebulae which OTA should I consider as 'Ultimate' from the following choices ?

1] GSO/Sky-watcher 10-inch F4
2] Celestron RASA 8
3] Sharpstar 200mm f/3.2 PNT Parabolic Newtonian Astrograph

I saw some great images from RASA 8 and they just blow my mind by showing some fine detail of faint galaxies in the background sky of the main targets which I feel just incredible.

Thanks
Abhijit Juvekar

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Pistachio_Enjoyer

Mar 10, 2023

The fundamental problem with what you want to image is that you're in a city, and thus experience light pollution. What is your area's bortle scale? To get quality images of fainter targets, ideally you would want to shoot from a bortle 5 or better zone.
I could perhaps suggest the RASA 8 since you're in a city. However, at 400mm of FL, don't expect to get much detail on small targets. As for the other scopes you provided, none of them have the focal length of the Ritchey-Chretien. So your RC 6 would effectively be the longest focal length system you have.

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Abhijit Juvekar

Topic starter

Mar 10, 2023

The fundamental problem with what you want to image is that you're in a city, and thus experience light pollution. What is your area's bortle scale? To get quality images of fainter targets, ideally you would want to shoot from a bortle 5 or better zone.
I could perhaps suggest the RASA 8 since you're in a city. However, at 400mm of FL, don't expect to get much detail on small targets. As for the other scopes you provided, none of them have the focal length of the Ritchey-Chretien. So your RC 6 would effectively be the longest focal length system you have.

I image from the sub-urban city sky Bortle 6-7

andrea tasselli

Frequent contributor

Mar 10, 2023

Abhijit Juvekar:
The fundamental problem with what you want to image is that you're in a city, and thus experience light pollution. What is your area's bortle scale? To get quality images of fainter targets, ideally you would want to shoot from a bortle 5 or better zone.
I could perhaps suggest the RASA 8 since you're in a city. However, at 400mm of FL, don't expect to get much detail on small targets. As for the other scopes you provided, none of them have the focal length of the Ritchey-Chretien. So your RC 6 would effectively be the longest focal length system you have.

I image from the sub-urban city sky Bortle 6-7

Then you're in the same league of mine. I'll suggest the 10" f/4 would be the right choice if coupled with the ASI1600. Aperture matters, a lot.

Jonny Bravo

Mar 10, 2023

andrea tasselli:
Abhijit Juvekar:
The fundamental problem with what you want to image is that you're in a city, and thus experience light pollution. What is your area's bortle scale? To get quality images of fainter targets, ideally you would want to shoot from a bortle 5 or better zone.
I could perhaps suggest the RASA 8 since you're in a city. However, at 400mm of FL, don't expect to get much detail on small targets. As for the other scopes you provided, none of them have the focal length of the Ritchey-Chretien. So your RC 6 would effectively be the longest focal length system you have.

I image from the sub-urban city sky Bortle 6-7

Then you're in the same league of mine. I'll suggest the 10" f/4 would be the right choice if coupled with the ASI1600. Aperture matters, a lot.

That's a whole lot of scope for a GEM45 to swing around... a 254mm f/4 scope is going to weigh in around 17kg and be over a meter long.

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andrea tasselli

Frequent contributor

Mar 10, 2023

Jonny Bravo:
That's a whole lot of scope for a GEM45 to swing around... a 254mm f/4 scope is going to weigh in around 17kg and be over a meter long.

Maybe not that overweight SW one. But there are other choices, more in line with the mount capabilities. At any rate I had my 10" f/6.3 on a GP-DX and it was tricky but doable.

Pistachio_Enjoyer

Mar 10, 2023

Jonny Bravo:
andrea tasselli:
Abhijit Juvekar:
The fundamental problem with what you want to image is that you're in a city, and thus experience light pollution. What is your area's bortle scale? To get quality images of fainter targets, ideally you would want to shoot from a bortle 5 or better zone.
I could perhaps suggest the RASA 8 since you're in a city. However, at 400mm of FL, don't expect to get much detail on small targets. As for the other scopes you provided, none of them have the focal length of the Ritchey-Chretien. So your RC 6 would effectively be the longest focal length system you have.

I image from the sub-urban city sky Bortle 6-7

Then you're in the same league of mine. I'll suggest the 10" f/4 would be the right choice if coupled with the ASI1600. Aperture matters, a lot.

That's a whole lot of scope for a GEM45 to swing around... a 254mm f/4 scope is going to weigh in around 17kg and be over a meter long.

It is doable. I've used an RC 10 on an EQ6-R which weighed similar to the proposed newt here. I've since bought an EQ8 however to handle the scope.