Thinking about a new telescope

[astrochris]

Hello everybody! I was hoping I could get some advice on buying a new telescope. Currently I own a Stellarvue SV105 APO but I've always wanted to take photos of galaxies and similar deep space objects. The SV105 definitely serves it's purpose for nebulae and large objects but I think I might be ready to move on sometime soon. I've also thought about possibly keeping my telescope and just adding the second telescope so I have the best of both worlds but that could be expensive to do.

The telescope I've had my eye on this month has been the GSO RC10" Truss (also known as TPO and AstroTech I think). It would fit perfectly on my new Astro-Physics Mach1GTO mount (barely but still within the limits). I would also like to point out that this telescope also shares the same 3" FeatherTouch focuser that my SV105 uses so that's a huge plus and will save me around $600+. What do you think of the GSO RC10 Truss? Do you have any experience with it or know anyone who has taken some amazing photos? This would be my first time using anything but a refractor and I understand it can be quite difficult getting into RCs due to collimation, etc. My main concern is the quality. I've never had a telescope made from the Far East. Any insight? I'm also up for any other OTA suggestions!

I am sure that this post belongs in the Equipment forum but I figured that since I was using it strictly for astrophotography it would be best placed in the Imaging forum.

 

PS I've heard this telescope has an issue with obstruction but I've also heard obstruction prevents vignetting. Any words on this?

[HunterHarling]

An sct+f6.3 reducer would work quite nicely

The GSO RC10 Truss looks good, but I think an sct could be just as good but a bit faster with the reducer..?

I have a c8 and it is quite good for small objects.

Hunter

[HunterHarling]

If you get the rc you may want this: Astro Physics CCDT67.

[astrochris]

I've thought about the SCT, like an Edge or something. The quality would be similar if not better than the GSO RC. I've just heard that RC's are best since they are specifically used for astrophotography. I'm a complete noob when it comes to anything other than refractors so I want the simplest thing for now. I heard SCTs have to deal with mirror flop and things like that.

[newbie alert]

The edge has mirror locks and as far as I can tell doesn't suffer with mirror flop as far as I know...only thing it's prob best using a oag if imaging and looks like you use a ccd , the celestron oag  isn't compatible spacing wise for use with a ccd.. you might have to look at other oag options..

[ollypenrice]

Don't think of this just from the scope point of view but from that of the scope-and-camera. Once you get into high resolution imaging you can easily find yourself trying to work at unachievable pixels scales. (At short focal lengths you are unlikely to run into a problem since anything from about 1.5 to 3.5 arcsecs per pixel will work fine. But at long FL you might put a DSLR in an SCT and find you're working at 0.3"PP which neither the seeing nor the likely guiding will allow, making it a waste of time.)

You can find out your pixel scale here. http://www.12dstring.me.uk/fovcalc.php

I doubt there is much point in going for anything less than about 0.7"PP. So it is very, very important to match your focal length to your pixel size.

The other way to get into the galaxies is to use a shorter focal length and smaller pixels. The (refractor) image below was taken at a focal length of only 1015mm but with a small pixel CCD working at 0.89"PP.

I wouldn't go for a classic SCT and F6.3 reducer because the optics are not that great for DS imaging (fine for visual) but the ACF/Edge do offer an alternative to the RC. The GSO RC can be a devil to collimate but can be superb when 'right.'

But above all, don't think 'focal length,' think 'arcseconds per pixel.' And don't fall for focal reducers on small targets. Check out this article. http://www.stanmooreastro.com/f_ratio_myth.htm *

Olly

* Edit. Use a focal reducer to bring yourself down to a better pixel scale or to widen the FOV. Don't use one to speed up capture on small targets. It won't.

[Anne S]

I'm using an Altair RC 6 inch with my SXH694 mono ccd. That gives me a pixel scale of 0.7. I therefore bin the ccd 2x2 which gives my 1.4, similar to my refractor. 

[astrochris]

Thanks so much for all the information everyone. I think I will just stay with the Stellarvue SV105 for now but upgrade my filters from Baader to Astrodon. Once I do that I will be purchase a second telescope. The Edge does sound pretty nice. I've also been thinking about the SV80 refractor for even wider field shots.

[ollypenrice]

1 hour ago, astrochris said:

Thanks so much for all the information everyone. I think I will just stay with the Stellarvue SV105 for now but upgrade my filters from Baader to Astrodon. Once I do that I will be purchase a second telescope. The Edge does sound pretty nice. I've also been thinking about the SV80 refractor for even wider field shots.

The Astrodon narrowband filters are a massive upgrade. Personally I think the Baader LRGB set is fine, though.

Olly

[astrochris]

You would not be the first person who told me that it is a massive upgrade. I'll be shooting for the 3nm this week. So you don't think the LRGB set should be upgraded? I've heard that there are sometimes reflectivity issues with the Baader filters.

Christopher

[swag72]

I use Baader RGB filters and as a luminance filter I use the Hitech IDAS LP filter... Ive got no desire to upgrade to Astrodons..... Narrowband however is a different matter  

[astrochris]

Thanks Sara. That's good to know. I actually got the idea of upgrading my filters from your website and your pictures  I wasn't sure if you had the Astrodon LRGB until now. Perhaps I will stick with the current LRGB set I have.

Christopher

[swag72]

Just now, astrochris said:

..... Perhaps I will stick with the current LRGB set I have.....

I would seriously consider sticking with them... Unless you have money burning a hole in your pocket that you just must spend... in which case, what the hell