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Telescope advice for Astrophotography

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#1 tbar23

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Posted 14 October 2021 - 11:11 AM

I know there are quite a few threads on this topic, and I have read several of them (but happy to be pointed to more). As is often the case, I’m coming from a specific situation which may change guidance. I am brand new to AP and have started to explore it with a Canon EOS RP mirrorless, an iOptron SkyGuider Pro and a few lenses (the kit 24-105 mm ST, a Rokinon 14mm F/2.8 and a Canon 50 mm F/1.8). I have not attempted many targets other than an untracked Milkyway (14 mm) from a reasonably dark location and a tracked Andromeda from my front yard (Bortle 5, tracked kit lens taped at 105mm).

The core of my question comes down to this: plenty of recommendations and marketing around RedCat / SpaceCat 51 and Radian 61. Some counter-thoughts around RedCat being an “odd” combination of telescope / wildlife photography lens and Radian being a well-marketed over-priced Sharpstar.

 

My EOS Rp, lenses and iOptron tracker are all recent purchases, and I will likely hold off a bit before getting a telescope. However, in preparation I’d like to start the research. I like what I have read regarding ease-of-use and portable and choosing a small refractor to get started (especially since my SkyGuider Pro probably needs to stick to small-ish).

So I’m looking for thoughts on good choices with a modest budget for 200 - 400 mm focal lengths that will allow for future upgrading to guiding and have relatively straight-forward mounting options for my EOS Rp mirrorless and won’t overload the SkyGuider Pro. The ones I am currently aware of include the two mentioned above WO RedCat/SpaceCat 51 and Radian 61. Should I be looking at Sharpstar? What about the WO ZenithStar series?

 

Thanks in advance!



#2 Hesiod

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Posted 14 October 2021 - 11:31 AM

The 24-105 f/4 is quite handy, and surprisingly good to be a kit lens even at f/4.

105mm may not seems much, but have very interesting targets to shot (this is a rather "classic" shot for summer https://www.cloudyni...85_10564553.jpg )

 

I have 3 star trackers, and avoid guiding them due to personal preferences (if use the guide prefer to use a full-sized mount): it is very possible to shot at 200mm or even at 300mm unguided if opt for fast glass.

The Canon EF200 f/2.8 sells around the same price of those small telescopes, or even less if can find one second hand: at f/2.8 it ensures that somewhat short subs and modest integration still will turn into pleasant pictures.

It is also smaller and lighter than 50-60mm sized refractors, which is greatly helpful when using a diminutive tracker, both because calls for less counterweights, and because the whole rig will be smaller and lighter.

It could be possible to get good results at 300mm too, but of course chances are lower and the whole thing a tad more tricky, so I prefer to suggest the 200mm.

As for zoom lenses the RF line has three "small" models which could be suitable; however two cap at 200mm, so I'd go for the prime (faster than the 70-200 f/4 and cheaper than the 70-200 f/2.8), while the RF100-500 is painfully slow.



#3 scadvice

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Posted 14 October 2021 - 11:54 AM

A recent video came out from a respected imager about the Sharpstar 61 linked below actually I linked the first two video's to give the full story. The WO ZenithStar and Redcat both have good reputations. I had the WhiteCat 51 which was a earlier version of the RedCat and it took excellent images. I had it on the SkyGuider Pro. The Radian Raptor looks very interesting. 

 

Notes:

  • The WO ZenithStar to get full field benefit requires a field flattener (cost about $200).
  • The RedCat does not need one
  • The Radian 61 does not require a flattener either, it's built in or at least included. It comes with everything you need thus the price a little higher. (Note I have not used one or seen one up close but if it fits within your budget I recommend it over the other two)

Helpful videos:

 

https://m.youtube.co...h?v=KAmNjvP3F20

 

https://m.youtube.co...h?v=6a6S6lMwooQ

 

https://m.youtube.co...h?v=KI6AK3JhTwo

 

 

 

https://m.youtube.co...h?v=Z4jB-GTA8nk

 

One last note. Tracking and guiding are not the same thing. Your setup with track the sky as it is. Guiding is adding a computer to the tracker that also corrects for star drift. Not really necessary with that setup if polar aligned correctly..


Edited by scadvice, 14 October 2021 - 11:58 AM.


#4 tbar23

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Posted 14 October 2021 - 02:10 PM

Thanks to you both. @scadvice - yeah, I was on a plane as I typed that thread and it wasn't super clear. I understand that tracking and guiding are different. The only point I was hoping to get in there is that I'd like the option to guide down the road.

I think I had read something about RedCat not having the necessary hardware for a guide scope, but it looks like they may have changed that on the latest version.

Will check out the videos, thank you.



#5 Enance42

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Posted 14 October 2021 - 02:28 PM

The Redcat can be used with either a seperate guide scope or an off axis guider. I chose the WO 32mm guide scope for mine.

#6 Enance42

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Posted 14 October 2021 - 02:30 PM

I forgot to mention that the optional Cat handle is needed to mount the guide scope on.


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