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  #1  
Old 13-04-2018, 11:45 AM
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Jsmitt94
Jacob

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GSO RC8/EOS 60D Astromod question

I am thinking of purchasing something like this in the future:
https://www.bintel.com.au/product/bi...ph-metal-tube/

As I am a newbie, I was wondering what else would be required to photograph using this astrograph with a DSLR (if a DSLR would even be appropriate).

On the subject of DSLR's, are there any places in Australia that can astromod my canon EOS 60D that won't cost me an arm or leg? I've also seen this Tan person from HK who also does it, and i've seen people on these forums recommend using him. Any suggestions?

TIA.

- Jacob

Last edited by Jsmitt94; 13-04-2018 at 03:48 PM.
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  #2  
Old 14-04-2018, 02:05 PM
benklerk
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Hi Jacob

I have the 6 inch version of what you are thinking of getting.

Few things
Do you have a guiding system in place? It is important to have a guiding in place.
Do you know how to collimate? RC is not a easy telescope to optically align with out the gear. It is worth getting this Bintel GSO RC Focuser Collimation Ring (RC6 and RC8), this will give you precise collimation.
I see that you have a HEQ5 pro, do you know how to polar align? With guiding and a good polar alignment you can expose for a few minutes.
The Heq5 Pro has a photographic limit of around 12Kgs.

Also you need a T-ring camera adapter and a T-adapter to use your DSLR.
DSLR is fine to start out imaging, you just need longer expose time and a lot more images to stack.

The picture attached is my setup for you to have a look. Im also looking at upgrading to the carbon 8" RC.
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  #3  
Old 16-04-2018, 12:16 PM
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Jacob

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Quote:
Originally Posted by benklerk View Post
Hi Jacob

I have the 6 inch version of what you are thinking of getting.

Few things
Do you have a guiding system in place? It is important to have a guiding in place.
Do you know how to collimate? RC is not a easy telescope to optically align with out the gear. It is worth getting this Bintel GSO RC Focuser Collimation Ring (RC6 and RC8), this will give you precise collimation.
I see that you have a HEQ5 pro, do you know how to polar align? With guiding and a good polar alignment you can expose for a few minutes.
The Heq5 Pro has a photographic limit of around 12Kgs.

Also you need a T-ring camera adapter and a T-adapter to use your DSLR.
DSLR is fine to start out imaging, you just need longer expose time and a lot more images to stack.

The picture attached is my setup for you to have a look. Im also looking at upgrading to the carbon 8" RC.
Thanks for the insight!

I have everything I need to image, it's more that I need to know what accessories are necessary to get this scope up and running. I know how to polar align and yes I do have a guiding system (still working out the kinks in PHD2, though)

So i need:
The scope
The collimation ring

Anything else required for the RC6/8?
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  #4  
Old 16-04-2018, 01:09 PM
benklerk
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When I was imaging with a DSLR I got this. https://agenaastro.com/hotech-2-sca-t-adapter.html
The T-ring screws onto it and that fits into the 2" adapter on the RC. It's a very good adapter and your camera will not move.

But yes, you need to read up on how to colimate a RC telescope. Its not a easy telescope to work with if you are new to this type of telescope. If other members comment. They would recommend you to get a takahashi collimating scope which is not cheap. I have one and a howie laser.

If your on Facebook, ask your question on this group. https://www.facebook.com/groups/943624572325939/
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  #5  
Old 16-04-2018, 05:15 PM
luka
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A nice summary of what is needed to get RC8 to its full potential is here.

It was already mentioned but it is worth stressing again, they are a pain to collimate and you will need a Tak collimation tool which is not cheap.

Long focal length will make it difficult to get good guiding results, especially if you are just starting. You may end up needing an OAG.

RC8 and HEQ5... did you check the weight limits? The stainless steel RC8 is 8kg already.
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  #6  
Old 16-04-2018, 06:27 PM
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blink138 (Pat)
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if you are in sydney you will need a good light pollution filter?
pat
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  #7  
Old 16-04-2018, 09:15 PM
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Jacob

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Quote:
Originally Posted by luka View Post
A nice summary of what is needed to get RC8 to its full potential is here.

It was already mentioned but it is worth stressing again, they are a pain to collimate and you will need a Tak collimation tool which is not cheap.

Long focal length will make it difficult to get good guiding results, especially if you are just starting. You may end up needing an OAG.

RC8 and HEQ5... did you check the weight limits? The stainless steel RC8 is 8kg already.
Yeah after all things considered, i'm leaning towards an RC6. With everything, price is not an issue. But thanks for the input

Quote:
Originally Posted by blink138 View Post
if you are in sydney you will need a good light pollution filter?
pat
I already have one
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  #8  
Old 17-04-2018, 08:33 AM
benklerk
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As you know I have the RC6. Few things you should know. At f9 expect longer exposer times.
You will got field curvature around the edges on APS size senors or larger which most DSLR have. You will need a field flattner which will reduce the curvature in the edges. You need at least a 8 inch telescope to use a APS senor. Why don't you look at a SCT (Meade, Celestron) they are much easier to use and still produce great images.
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  #9  
Old 17-04-2018, 12:22 PM
kens (Ken)
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What is wrong with your current OTA that makes you want to change?
I would think better options would be (in no particular order): electronic focuser, cooled camera, better mount
If you go with the RC8 you would do better with an EQ6 class mount plus I'd add an OAG, collimation ring and focal reducer.
With your current OTA or the RC6 the HEQ5 should be ok - especially if you use an OAG.
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  #10  
Old 17-04-2018, 01:27 PM
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Jsmitt94
Jacob

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Quote:
Originally Posted by kens View Post
What is wrong with your current OTA that makes you want to change?
I would think better options would be (in no particular order): electronic focuser, cooled camera, better mount
If you go with the RC8 you would do better with an EQ6 class mount plus I'd add an OAG, collimation ring and focal reducer.
With your current OTA or the RC6 the HEQ5 should be ok - especially if you use an OAG.
A cooled camera is definitely higher on the agenda, i'm just talking down the track if I ever wanted to change scopes that's all. But i'm loving the insight from everyone, much appreciated! Definitely opened my eyes. I just love the way images from an RC6/8 come out, so hopefully one day i'll be able to replicate some of those beautiful shots!
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  #11  
Old 17-04-2018, 05:44 PM
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doppler (Rick)
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Hi Jacob, I'll throw my 2 cents in. I bought a GSO RC6 to use as a grab and go (a half decent 5" or 6" astro capable refractor would cost a lot more)

The only thing I don't like about it is the F9 part, it's seriously slow. But as far as collimation goes I have only ever had to tweak the secondary, and the field is flat (on my crop sensor 1100d anyway), which is why I got it in the first place, no reducers or correctors needed.

I think most people get into strife when they start messing with the primary collimation, I was told to leave that alone and just micro adjust the secondary.

Your HEQ5 pro will handle the RC6 or 8 , but if you want quick results photography wise the lower the f ratio the better. For the same $ I would be looking at a 8" F4 reflector, you will need a coma corrector and some collimation skills/patience but once set up you will get some nice images quick and easy.
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  #12  
Old 20-04-2018, 09:35 PM
dpastern (Dave Pastern)
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I have no personal experience with the GSO RCs, but all of the tube versions have the original focuser, which SAGS.

Also, the focuser assembly is attached to the primary mirror cell too, and they are a nightmare to collimate by every single account I've read. You may manage to collimate the scope in one azimuth direction, and it changes under load due to gravity in a different one as you point to a different part of the sky. Even shift of a mm is enough to throw collimation out.

Premium RCs (DSO, Knaeble, PlaneWave etc) are difficult to collimate too, but their mechanical tolerances are far better than GSOs.

note: the truss versions (10" and up) have been re-designed with the v2 focuser assemblies are are much better with holding collimation I believe.

There are a lot of these on the 2nd hand market, and i personally believe that this is because the build quality is not the best, and they are very difficult to collimate. Caveat Emptor.

I base this post on a LOT of research on the GSO RCs btw.

edit: don't rely solo on cheshire/tak collimation devices. Many people are using DSI's excellent user manual to star collimate the GSO RCs and I really recommend that you go with that method:

http://deepskyinstruments.com/truerc...ers_manual.pdf
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