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Old 09-11-2019, 10:14 AM
Emuhead
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RASA 8" vs EDGE HD 8"

Hi all,

I've been doing a lot of research recently on what telescope to buy for astrophotography and I've settled on either a RASA or an EDGE HD with Hyperstar. My budget allows for 8".

Would anyone with experience with both be able to confirm if there are differences in image quality? Any pros/cons/tips?

I'm looking to get a Skywatcher EQ6-R Pro mount and likely a ZWO cooled colour camera (ASI183MC) along with a guide scope and camera (ZWO ASI Air kit). I may look at monochrome down the track, but not right now.

I'm interested in mainly taking nebula photos from a dark site.

Last edited by Emuhead; 09-11-2019 at 10:25 AM.
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Old 09-11-2019, 10:54 AM
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h0ughy (David)
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Well mate, it's like having a good set of golf clubs as they all hit a ball but each has a different effects.

I have both. If you are never going to buy a eyepiece then get the RASA, and an electric focus motor and you will need to buy a solid dew shield from astrozap with cover. If you're going to do some other things then get the edge.
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Old 09-11-2019, 12:03 PM
Emuhead
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Thanks, I'll add the autofocuser & dew heater to my list. How is the hyperstar performance compared to the RASA would you say? Also read the back focus is quite short with the 8" RASA, hopefully doesn't pose a problem. If you could only have one, which one?
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Old 09-11-2019, 12:53 PM
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Yes life at f2.2 is pretty good
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Old 09-11-2019, 01:00 PM
casstony
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I imagine the ball bearing mounted mirror of the RASA makes focusing easier in comparison to the greased sliding mirror in the Edge HD?
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Old 09-11-2019, 01:11 PM
glend (Glen)
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Focal length is significantly different, even if you did invest in the Edge HD reducer (not cheap btw). I have owned an 8" Edge HD, nice scope, but can exhibit mirror flop if your imaging across the meridian. And without the reducer it is dog slow. The RASA is a Ferrari by comparison, but you Can't use it visually unless your doing EAA to a screen.
For nebula (traditionally wide field) at a dark site, I would choose the RASA.
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Old 10-11-2019, 11:22 AM
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Quote:
Originally Posted by glend View Post
Focal length is significantly different, even if you did invest in the Edge HD reducer (not cheap btw). I have owned an 8" Edge HD, nice scope, but can exhibit mirror flop if your imaging across the meridian. And without the reducer it is dog slow. The RASA is a Ferrari by comparison, but you Can't use it visually unless your doing EAA to a screen.
For nebula (traditionally wide field) at a dark site, I would choose the RASA.
What does EAA stand for Glen?

Greg.
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Old 10-11-2019, 11:43 AM
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What does EAA stand for Glen?

Greg.
Electronically Assisted Astronomy.

The scopes, sensors and software at a stage where this is getting interesting...
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Old 10-11-2019, 01:08 PM
glend (Glen)
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What does EAA stand for Glen?

Greg.
As Dunk said, the tech enabling realtime image capture is pretty advanced now. High frame rate capable cameras, and "Live Stacking" software allow image building with presentation to a screen.
So a RASA, could be used in this mode, in my opinion, as the cameras exist to fit within its central obstruction without increasing block out at penalty of reducing resolution. I am suggesting an observational RASA using this technology, and of course it can image in the more traditional mode as well.
The RASA optical speed gives it significant advantages in this configuration.
If I could afford it, I would build it.
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Old 10-11-2019, 10:09 PM
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I imagine the ball bearing mounted mirror of the RASA makes focusing easier in comparison to the greased sliding mirror in the Edge HD?
you still get a bit of a wobble but it is very minor when compared the the Edge
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Old 11-11-2019, 11:07 AM
Emuhead
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Thanks for the responses... decision in favour of the RASA 8 has been made.
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