Telescope Question

[cjsims86]

Hi All,

New to the site and I've got a burning question. I can buy a 6" 900mm F6 Newtonian scope which , apparently is good for magnifications up 300x. Though reading the internet the real maximum magnification is limited buy light pollution and atmospheric to around 130x.

Fine I understand this. Seems perfectly reasonable.

I could buy an F7.5 80mm ED refractor. Which is apparently good for magnifications to 160x. I could also fit a focal reducer to give me a wider field of view and reduce to scope to an F stop of around 6.8.

So, here comes the question at last, if real magnification is limited to around 130x due to seeing conditions etc is it worth me just buying the refractor instead of the reflector. Will I see just as much as the 6" reflector apart from the F0.8 (13-14%) loss in light gathering? (mmm probably answered my own question there).

Will I see any deep sky objects such an nebula with the refractor? I've only ever owned a small 3" Newtonian in the past and I've never looked at the night sky with a refractor, so I'm in a bit of a quandary as to what to buy.

I've just bought a HEQ5 Goto mount off eBay and I can't decide what scope to buy. The Newtonian s look so unwieldily.

I know a telescope is about light gathering rather than magnification but does an F6 refractor gather as much light as a F6 reflector?

Regards,

Chris Sims

[rowan46]

its not about focal ratio when it comes to visual, its about apparture. the 6inch even including its central obstruction will collect more light than a 80mm scope. hence it will be better on deep space objects. there may be a trade off in contrast. but I doubt it. If you intend imaging go for the refractor it puts less stress on the mount

[NGC 1502]

Hi Chris, welcome to SGL. A 150mm scope will collect more than 3 times the

light of an 80mm, so will show fainter objects.

80mm = 5027 sq mm

150mm = 17674 sq mm

Best regards, Ed.

[brantuk]

Magnification depends primarily on the "seeing" and imho I think you'll find that you can get a bit more then 130x. On a good clear night some scopes will work well at 200x to 250x.

Of course it's better from a dark site with no LP, and quality of eyepieces and optics plays a big part. If the object is around the zenith this will be "seen" better than low on the horizon, and it also helps if the moon ain't around - especially for dso's

[rowan46]

Ed has reminded me of my manners. I hadn't noticed it was your first post so a big welcome to sgl from as well.

[John P]

Hi Chris and welcome to the forum.

[themos]

No matter what you buy you will probably think you should have bought something else at SOME point! You will probably outgrow the 6" Newt but an 80mm ED refractor will always come in handy. On the other hand, you will get more from the 6" Newt than the frac if that's the only scope you ever buy.

[perrin6]

Hi Chris!

A 3 inch refractor is a great scope but a 6 inch reflector is better overall, in most ways ie. light gathering power (you'l see more faint objects) and resolution (you'll see more detail), unless the 6inch is absolutely terrible quality and the 3 inch is fantastically good. There are subtle differences that complicate choosing between the two telescopes but they are minor because the much bigger aperture of the reflector makes it a better scope.

Claims about how much magnification an individual telescope/type of scope/ specific aperture etc, need to be taken with a giant pinch of salt. Even when the atmosphere is turbulent I still use quite high magnification because there is usually the occasional second when it is steady and good detail is seen.

I think everyone tends to have different opinions about 'ideal' magnifications but if you get a telescope you will gradually 'aquire' several eyepieces and find out your own personal preference what magnifications you want to observe with on different objects. Part of the fun is to find out by doing it yourself.

I often use 443X on various objects 'just for a laugh' and am surprised how good the view is so I think my message is 'go ahead universe - make my day' as Clint Eastwood might say if he were trying high magnifications!

[cjsims86]

Thanks for the replies everyone. I'm waiting for an 8" PDS Skywatcher to turn up at the moment and the supplier has given me the option to cancel the order as they're in short supply and wont ship 'til March. Didn't know whether to just plumb for a refractor. Suppose I'll just have to wait.

I do want to have a go at astro-imaging though I think that'll be a long way off. Don't want to try running before I can walk.