Advice for a second scope

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Advice for a second scope

Postby ritchiejb » Sun Dec 24, 2017 4:42 pm

I've got a 6 inch newtonian reflector and I was thinking of another telescope to pair up with it, so that I can see most things in the night sky. I'm not fussed about astro-photography (I don't own an SLR anway) but I do like to watch and take notes etc.
I'm a bit rusty since I bought my last scope 8 years back and haven't used it much lately, so what kind of scope would best pair up with that - to allow viewing of deep space objects, nebulae and galaxies etc ..... I was thinking an 8 inch Dobsonian (my budget is around £400) but I can see that lots of Maksuto-Cassegrains are available with computer control for less than that - though I believe in terms of use type, they are much the same as my current reflector.
So, in short, Dobsonian or M-C type, which would be better for me? Portability's useful but I only really go in my back garden though being able to collapse and store it easily would be useful - so am I thinking right with a Dobsonian or barking completely up the wrong tree?
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Re: Advice for a second scope

Postby Gfamily2 » Mon Dec 25, 2017 12:41 am

The traditional advice has been that a 2" increment in scope size doesn't really give much of an appreciable difference to what you can see - so if you were going to move up with a Dob, I'd say aim for a 10" or 12" aperture instead.
For Maks in your price range, you would probably either get a 5" (127mm) scope on a GOTO mount or maybe a 6" scope as an OTA only. These will give you a higher magnification with any eyepiece than your current scope, but they don't capture any more light, so they are only better for small bright objects (like planets), or for looking in close detail at the moon or sun (with appropriate filters).

Do you have a local astro society? They can be great at regenerating interest in what you can see with your current scope, as well as giving you a lead into where you want to go next with your Astro hobby.

One thing I can say for the 5" Mak is that it makes a very transportable scope for taking out to dark locations (including packing in the car for holidays), as it doesn't take a lot of space, and it benefits from dark skies.
Scopes: Meade 8" SCT, Skywatcher 127mm Mak
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Re: Advice for a second scope

Postby Aratus » Mon Dec 25, 2017 11:54 pm

Perhaps a few figures will make it clear what happens when you move up to a larger aperture.
A 6" reflector has a theoretical limiting magnitude of 14.1. A similar telescope with an aperture of 8" has a limiting magnitude of 14.7. A 10" gives 15.1. Bear in mind that an increase in 1 magnitude gives an increase in brightness of x2.5. More interesting is the resolving power of a telescope which goes from 27 to 36 to 46 with the same increase. That makes a difference to splitting double stars, and seeing planetary and lunar detail.
I use an 11" Celestron SCT (CPC 1100) on an equatorial wedge, housed in a 2.2m Pulsar observatory. I use a ZWO ASI1600MC and Canon 500D for imaging.
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Re: Advice for a second scope

Postby EIZO » Tue Dec 26, 2017 11:13 am

I have a SC and Refractor my next buy IS an 8" DOB, I can't avoid the reality that they are soooo easy to use as a grab and go
Celestron Edge 8" Evolution, Esprit 120mm triplet, Sky Tee2, WO Binoviewers, 2" and 1.25" eyepieces, ZWO ASI 178MM camera, Neximage 5, Nikon D4s, D810, Nikkor 70-200 F2.8, Nikkor 14-24, Nikkor 70-200, Nikkor 24-120, Sigma 150-600 Sport
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Re: Advice for a second scope

Postby The Man with the Corrugated Iron Roof » Sun Jan 14, 2018 8:47 pm

I would agree with the comments that an 8" won't show you much more than a 6". I would consider a big Dobsonian but first I would "squeeze the pips" out of what you have. I only have a limited budget but find that there's loads of objects within the range of my 'scopes that I haven't seen yet. Something like the Cambridge Star Atlas will help you a lot. Also, you can look at better eyepieces if your main interest is visual and you can even get a good DSLR with your budget.
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