Reflector or Refractor

[Pilchy120]

Hi,

I would like to know what telescope is better.

Is a refractor better or a reflector better.

I would like to be able to see deep space objects in detail with ease

Thanks in advance

Pilchy120

[haitch]

Well, if you take a reflector and a refractor of similar optical quality and aperture I'm sure the refractor would win hands down. Thing is it's not that simple.

There are loads of factors that make various telescopes more suited to different purposes (we haven't even mentioned catadioptrics yet). Bottom line is there is no perfect telescope just the best suited one for what you want to do that is within your price range. Refractors of a decent quality also tend to be more expensive than a similar aperture reflector.

If your interest is viewing deep sky then you need as much aperture as you can get. You'll struggle to find a refractor above 150mm aperture whereas I think Orion Optics have just introduced a 500mm reflector. Now that's going to give you masses of photon gathering potential, a veritable "light bucket".

The big question is how much do you want to spend? Once we have an answer to that I'm sure responses will come flooding in explaining the best way to dispose of your cash.

Btw seeing Deep Sky Objects (DSOs) in detail is unlikely unless you've large quantities of cash to throw about. With many DSOs all you can hope for is a grey faint fuzziness.

[Catanonia]

I have 2 refractors and the larger one a SkyWatcher ED120 Evostar Pro is just under 1 grand in price new. If you look at my website in my signature you will see the type of images a newbie can do with it for comparison (I have been at this 2 months with lots to learn).

Most of the images are cropped about 50% to get close to the galaxies and that is the problem with refractors. Take longer to get the same number of photons, but easier to setup and better quality images.

Now If i want to go bigger, well now looking at £1000's more for a bigger and better refractor.

Hope this helps on the refractor side of things.

[blinky]

Bear in mid that what you see imaging wise is NOT what you will see when looking through the scope, the camera's can take very long exposures and as a result llight gathering ability is not that major a factor when choosing an imaging scope.

Back to your original question: If you want a scope to see DSO's then I would say there is really only one choice - A Dobsonian reflector, unless you want to do some imaging in future then I would get something like an 8" Newt reflector on an EQ mount.

BTW as for size of Dobsonian (Should you wish to go down this route) it is simple - Get the biggest you can afford but also make sure you can move it and transport is happily.

[Kai]

Agree with Blinky , i have a 12 inch Dob for visual but a Short tubed refractor for imaging.There is no way that you can see the same through the two scopes.

A 8 inch Newt on a eq mount seems to be a good compromise

[haitch]

There are refractors of up to 6" aperture that won't break the bank (That's a relative statement as I don't know what you have in your bank) but they will be known as achromatic. Basically a glass lens bends different wavelenghts of light by varying degrees so the red, the blue and the green light won't come to focus at the same point. This causes a colour fringe around brighter objects. It can be reduced to some degree by filters. If you want to avoid that problem you need an apochromatic refractors designed to eliminate this problem through exotic glasses and lens arrangement. True apochromatics are called triplets and are the holy grail of refractors. Guess what...they're damn expensive!

I qualify the above by saying that I have never owned a refractor for astronomy apart from finderscopes. It is all just gleaned from reading threads on these forums.

I started in astronomy with a 6" reflector on an eq mount that I picked up 2nd hand for around £100 on ebay. Avoid the cheap new ones on there such as Seben - they use spherical mirrors rather than parabolic then try to correct the error in the optics with a lens built into the focusser. My father-in-law has one so I know they perform poorly.

I mentioned an Eq (Equatorial) mount then. That is a head for a tripod or pier/post that, when correctly aligned with the Earth's rotational access, make it easy to follow an object as it drifts across the sky. The other way of mounting is Altitude Azimuth (Alt Az) with Altitude being up & down Azimuth being left and right. Both types can have motors and computerised controls fitted to automate this.

The trouble is the more you spend on your mounting the less you'll have left for your optics (which is what you want the most of if you intend to observe visually isn't it?). Good old John Dobson came up with a really simple Alt Az mounting for a large reflector which has been termed a Dobsonian or "Dob". Dobs must be the easiest telescope mounting to set up and use. You simply place the base on a flat surface, rest the Optical Tube onto the base, possibly tighten a couple of knobs and start observing, no fiddling, no alignment . The beauty of this system is that you spend virtually all your money on the biggest and best mirror you can get and there's no learning curve to using it apart from finding you way around the sky. The Dob has recently been given goto abilities by a few manufacturers if learning the sky sounds daunting but that's just something else to spend your money on again rather than optics and finding things yourself can be very rewarding. If you want you can add various angle measuring devices such as a Wixey angle gauge to helps you find things (usually termed push to).

If at some point in the life of your scope (you may find you get a regular bout of aperture fever and a compulsion to buy a bigger scope) you decide to image deep sky objects then a Dob won't be for you as you'll need the tracking abilities of an eq mount for the long exposure times. Then again if you are going to image you may want a completely different type of scope as reflectors do have an inherent problem of coma most noticeable in faster optics and the central obstruction caused by the secondary mirror is believed to impact on contrast when imaging. The speed of optics is measured as an F ratio and is a ratio of the focal length of the scope to its aperture. Above about f7 is getting fairly slow. f5 and lower is considered fast. Most large dobs are fast simply because of the practicality of how long the tube would need to be make them slower (you could easily end up needing a step ladder to view) but also because their main purpose (DSOs) requires wider field brighter images.

You'll see from my sig I currently own a 14" (354mm Dob) and I love it. I'm intersted in viewing DSOs too so I hope I've managed to be a bit balanced in my response.

[arad85]

I would like to be able to see deep space objects in detail with ease

So would I! but as a previous poster has said, they're all just grey fuzzies unless you're really in a dark sky site and you have top end equipment. Best views you'll get are with the largest aperture you can afford/manage. For most people, that's a 12 of 16" dobsonian - although you can get larger from other places, but the price seems exponential.

[Doc]

Even with a 16" dob from light pooluted back gardens they only show a grey smudge on most galaxies. There are the exceptions of course M42 is fsntastic, actually shows colour and M31, and M51 will show some dust lanes.

I'm saying this is because what really makes a difference is dark skies, much better then any aperture increase.

[Astro_Baby]

Agree with doc - the common mantra is aperture, aperture, aperture wheras I'd say its more truly location, location, location.

Even reasonable local dark sky sites haveny shown the same quality of view that Salisbury did last year.

As already said you wont see much detail almost no matter what size aperture you have. Even under good conditions most of the deep sky objects are pretty faint and fuzzy.

As to which is better well all the really serious telescopes are reflectors I'm off to hide behind the sofa now to save myself being lynched :)

[Beulah]

I concur to what has been said here.

If it is any help, I found a webpage describing "limiting magnitude" of different apetures of telescopes: BTW, ignore the strangely titled link, LOL

Choosing a 35mm camera

[Catanonia]

Yes well pointed out, these are NOT VISUAL. These are obviously images built up over 10's minutes to hours.

Depends if you want visual or imaging. Visual, bang for buck seems to be a large Dobby

Cat

Bear in mid that what you see imaging wise is NOT what you will see when looking through the scope, the camera's can take very long exposures and as a result llight gathering ability is not that major a factor when choosing an imaging scope.

Back to your original question: If you want a scope to see DSO's then I would say there is really only one choice - A Dobsonian reflector, unless you want to do some imaging in future then I would get something like an 8" Newt reflector on an EQ mount.

BTW as for size of Dobsonian (Should you wish to go down this route) it is simple - Get the biggest you can afford but also make sure you can move it and transport is happily.

[arad85]

Visual, bang for buck seems to be a large Dobby

Cat

Not sure the view would be very good through this sized Dobby

[SpookyKatt]

Not sure the view would be very good through this sized Dobby

Hehe, Astronomy joke of the day...

[mik]

For me it is a small Refractor every time 66 to 80mm apo not important to me either, why ? well i have back problems and i can lift it without problems, also i can get setup and viewing very quickly and have a few hours at the eyepiece,

The best scope is the one you get to use and enjoy.

Regards Mick.

[Pilchy120]

Thanks everyone for your advice

Brought an 80mm Meade DS 2080 (refractor)

regard Pilchy120