When would you choose refractor scope over reflector scope with a bigger aperture?

[adamjames101]

Picking my first scope and am still puzzled by the fact that for the same price you can get refractors and reflectors, and the reflectors have some much more aperture. When would you pick the long refractor over bigger aperture?

[NickK]

No diffraction spikes

Seriously though, just imagine if Hubble was a refractor! (focal length of 57.6 m)

[kniclander]

when you see one and see how beautiful it looks:)

plus some people prefer the view through a nice refractor - it may be more "contrasty", also some people don't really get on with dob mounts (especially people who like lunar and planetary stuff) and it's probably easier to mount a refractor than a largish newtonian on an equatorial or a (non-dob) alt-az mount.

ideally have one of each:)

[brantuk]

A couple of reasons spring to mind. AN 8" reflector will cost around £300 - a refractor of the same aperture would be over £5000. There are two types of refractor - appochromatic and achromatic. The former consist of more glass elements and are well corrected for spherical and chromatic aberration, made of low dispersion materials, and lend themselves nicely to long exposure photography.

The later are not so well corrected and only bring two wavelengths of light together. Achros tend to have longer focal lengths and are good for planetary observing. They are a lot cheaper.

If you want to look out deeper into space then collecting photons is the game and larger apertures gather a lot more (faint) light. Newtonians are mirror based so relatively much cheaper for the larger apertures. People who like to observe only go for the larger appertures and short focal ratios - typically big newts on dobsonian bases.

Hope that all makes sense

[rfdesigner]

Generally I'd buy quality over quantity, but on balance I'd buy both.

Refractors can be good for wide field work, where a short focal length necessitates a smaller aperture, and a Newt with a short focal length and wide field would impose a very large secondary mirror, thus you end up losing a lot of light to the secondary blocking the primary... so the wide field refractor fits where the newt can struggle.

Portability also needs to be considered. If you live on a dark mountain top, then it won't be an issue, chances are you don't and like the majority need to travel to a dark sky site, in which case you need something you can carry and will fit in your boot/rucksack/flight-bag, this is one other area that the refractor can win out over the Newt.

Clear skys.

Derek

(who owns 3 newts)

[NickK]

Imaging means you can get away with a smaller aperture if you want a wider field of view. There are plenty of people that do imaging with 66-90mm aperture as the small scope is lighter which means a less bulky mount.

[hunterknox]

When you can't be bothered with collimation

When you want to avoid diffraction spikes and coma

When seeing is a greater limit than aperture

When you want to be wilfully different

[Caldwell 14]

When you can't be bothered with collimation

When you want to avoid diffraction spikes and coma

When seeing is a greater limit than aperture

When you want to be wilfully different

I concur!

[ronin]

Do you really want a telescope that is a dinner plate with some aluminium sprayed on it?

[Chris H]

When you want nice wide field views.

[rfdesigner]

Do you really want a telescope that is a dinner plate with some aluminium sprayed on it?

Isn't that what Hubble is?

[ismangil]

When you want nice wide field views.

I prefer a binocular for widest view

[Grotemobile]

All i want is at least 200x mag.I am a lunar & planet nut.Dont do wide field.Got to be at least a f10 scope.This is the way to go.

Steve.

[onesmallstep]

Hi

For visual observing I would choose the reflector (see sig for my preferred choice). If I wanted to image or have a one-size-fits-all scope for imaging and visual I would choose the refractor (80mm apo or larger).

[Tim]

Do you really want a telescope that is a dinner plate with some aluminium sprayed on it?

Like Hubble you mean?

[LukeSkywatcher]

For me personally, my 90mm refractor which is f11 (f/l 1000mm) on an EQ mount has given me the best views of the planets. I just dont seem to get the same planetary views with my 130mm (f5..........f/l650mm) Dob.

I now also have a 200mm SCT, but its new and i have not had a chance to use it.

I have it in my head that for planets................it really isnt aperture, its focal length.

Am i wrong?

[rfdesigner]

For me personally, my 90mm refractor which is f11 (f/l 1000mm) on an EQ mount has given me the best views of the planets. I just dont seem to get the same planetary views with my 130mm (f5..........f/l650mm) Dob.

I now also have a 200mm SCT, but its new and i have not had a chance to use it.

I have it in my head that for planets................it really isnt aperture, its focal length.

Am i wrong?

You need everything, but a dark sky.

Aperture

Focal length

Quality

Seeing (which is where Newts used to fall down, until they started getting fans added)

Derek

[Ags]

Get a mak and have a refractor and reflector all in one package. No need to fight. :-)

[Flea77]

When would you pick the long refractor over bigger aperture?

Any time and every time

Allan

[swamp thing]

Depends what you wanna observe.

Choose your tool To fit the job. That's the best way to do anything successfully.

Basically it's horses for coarses.

If your interest is visual observing of faint Galaxies, then a small frac is on a loser from the outset.

On the other hand, if you wanna take pics of them, then a small frac is very good indeed.

All scopes have their place.

I have a big hole in my scope line up that a nice frac could fill very nicely. Luckily I observe with others that own them and are generous enough to let me have a gander through theirs.

Mmm! Nice

Regards Steve

[russ.will]

I have an 8" Newt for the great views it gives of things bright/dim and near/far. I've just bought an 80mm APO frac, because I think it will be a better tool for imaging the above, plus it will be easier to take on holiday.

There is no correct answer to the OPs question, just bias depending on what you like looking at or taking photos of and when you would like to be able to do it. Judging by some of the answers above, that bias can be amplified by how much grape you have consumed before the sun is over the yard arm.

Russell

[adamjames101]

I am now swinging towards a refractor as i want to primarily view planets, but what will the minimum aperture I should look at? It 70mm too small?

[johninderby]

A dob can actually do very well on planets so it's always worth considering an 8" or 10" one.

However for refractors 80mm should be the minimum but 100 would be preferred. A long focal length achromatic refractor will do very well on the planets and they do cool down quickly. APOs are nice but a lot more expensive.

On a budget the Vixen A80MF Refractor would be good.

http://www.firstlightoptics.com/vixen/vixen-a80mf-refractor.html

The Tal 100RS Refractor is very good and not that expensive.

http://www.firstlightoptics.com/tal/tal-100rs-refractor-optical-tube-assembly.html

The Lyra Optic 102 f/11 is a bit better optically than the TAL but has a much higher build quality similar to a William Optics scope.

http://www.lyraoptic.co.uk/Telescopes-Accessories.html

John

[adamjames101]

What is your honest opinion on on the skywatcher startravel 80 EQ? Or is it too short in focal length to have the benefits of a refractor?

[John]

What is your honest opinion on on the skywatcher startravel 80 EQ? Or is it too short in focal length to have the benefits of a refractor?

It's a fun portable scope for a quick look at wide fields of view. Good to have on holiday. It's not going to rival an F/10 refractor for the moon or planets though.