refractor telescopes

[Kirscovitch]

Hello again. I've recently bought a 130 reflector telescope. Being a newbie I hear they are better for nebulae and galaxies and such but not as good for planets. That they don't produce sharper images as would a refracting scope would. Any tips on a cheaper refracting scope? I am not looking for anything fancy. My budget would be about 200. And if my girlfriend found out I spent that much I would probably be on the couch for a month lol. Is there anything that good and that cheap out there? I've been looking but not too sure since I just spent a fair amount on my reflector. And if I am gonna spend some bucks on a different scope I want to make darn sure it's exactly what I'm looking for for the price.

[Stu]

I would just stick with what you have got for a while and get to know how to get the best out of it. There are many different sorts of refractors, and very simplistically the chances are for £200 you won't get one which gives better performance than your reflector.

Most cheap refractors are achromatic, which means they suffer from chromatic aberration ie on planets you will see colour fringing around the planet which will rob it of some contrast. You would need to get a reasonable apo or long focal length achro to give you better performance. The latter may be a possibility but they can be more challenging to mount properly.

With your 130, make sure it is collimated well, and cooled properly and then spend plenty of time at the eyepiece. The detail will emerge as you train your eye and the moments of good seeing come and go.

Stu

[Stu]

Oh, and perhaps look at a better eyepiece or two for higher power. Something between x150 and x200 will give good performance on Jupiter for example. BST's or Vixen NOL's have good reputations

Stu

[iksose7]

£200 would probably be better spent on a pair of good binos rather than a horrible scope. Like Stu said, use the 130 for a while and see how you get on.

[michael.h.f.wilkinson]

A well-collimated Newtonian of 130mm will take any 80mm refractor in the same price bracket to the cleaners on planets. It should even give my APM 80mm triplet apochromatic refractor a serious run for its money (probably providing more detail at slightly lower contrast). The idea that Newtonians are worse on planets and better on DSOs is a bit of a myth. At the same aperture (e.g., comparing a 130mm Newtonian to a 130mm refractor) an apochromatic refractor will outperform the Newtonian on both planets and DSOs, simply because it gathers (a few percent) more light (having no central obstruction), and has better contrast (also due to the lack of central obstruction). However, with a slow Newtonian, this difference is vanishingly small. My former 6" F/8 had a central obstruction of a mere 22% by aperture or 4.84% by area (or 0.0538 magnitude). Its sharpness on planets was excellent. A 6" Newtonian is well within the budget of even beginning amateur astronomers, whereas an apochromatic refractor of a similar diameter is something most of us dream of. Even achromatic refractors (which have reduced performance on planets, due to chromatic aberration) are generally more expensive. So when dealing with bang-for-buck on planets, Newtonians are great.

The above advice on getting better EPs is excellent (a decent pair of binoculars is also worth considering, but not for planets).

[Stu]

Oh, and perhaps look at a better eyepiece or two for higher power. Something between x150 and x200 will give good performance on Jupiter for example. BST's or Vixen NOL's have good reputations

Stu

Sorry, NOL should read NPL

Stu

[ollypenrice]

It isn't true that refractors, ipso facto, produce sharper images. For the same aperure they usually do if they are of extraterrestrial cost! If they are basic simple designs they'll be outlcassed by larger reflectors.

The kind of refractors that people (like me  ) bang on about cost several thousand. On a budget you won't beat a Newtonian.

Olly

[chiltonstar]

$200 doesn't buy an awful lot new, even in the US.

I think the advice re better EPs, bins, and getting to know the existing scope, and the sky well, before moving on is very sound.

Enjoy, and clearer skies than we get!

Chris

[emadmoussa]

Like everybody said, better stick with your scope provided you know to precision collimate it. If your budget is £200, then you could always find a 200mm Dobsonian second hand, they're brilliant on planets and also delve deep into deep sky.

As for refractors, a decent refractor will be way above your budget and your girlfriend will surely know and you'll end up on the couch. Nah, but seriously, refractor do produce sharp images, but like Stu mentioned above unless they're well corrected to reduce color aberration they won't be great on planets. You'll always see this horrible purple or blue halo around bright objects. When I say 'corrected' I mean either a high end achromatic or apochromatic  - and these can get ridiculously expensive.  For example, a decent 150mm reflector will not outperform a decent refractor of the same focal length, but the difference will not be striking by any means. Plus, while you will pay something under £200 for the reflector, the 150mm frac will be at least 3 times the price..

So again, if you could manage to get yourself a 200mm Dobsonian then you'll be sorted. It's pretty much as close as it could get to all-round a good telescope that functions well on planets and deep sky objects.

[emadmoussa]

Oh, sorry, I realized you were saying $200 not £200. ($250)...hummm...I would target the second-hand market then.

[ronin]

As the question was a cheap refractor to suppliment the reflector, here goes:

Your 130 you do not specify as P or not.

If it is about f/8 then it could be a spherical mirror and you will get a less distinct image.

For $200 I cannot see anything, the one scope that comes to mind is the Skywatcher Evostar 90, but there is some "arrangement" whereby Skywatcher do not sell in the US. If they are sold it will be under another brand, try Celestron and Orion.

The Evostar 90 OTA falls easily within budget, there is a 102mm but it seems to not be sold as an OTA only here so cannot guess at a cost.

For the planets you do not need a great magnification for Jupiter, really 80x and above is enough, actually 60x is fine.

For Saturn you need moore, 100x is I suspect the minimum, 120x gives a fair image, 140x-160x better

For Mars you need a lot to see anything of significance as in 200+ and preferably more.

Binoculars will be of little use to see detail, they generally do not achieve the magnifications you require, unless they are a lot more then the budget you are thinking of.

Problem is that the US has a different range, well different brands at least with different models, and many here do not have a good list of retailers to look through.

There is a Vixen 80mm at $230 on Agenaastro.

Astronomincs sell Skywatcher but only the higher spec ED range, no achros.

Cannot see anything suitable on Canadian Telescopes either - the Antares 100 there looks suitable but it mentions a correct image and not keen on a correct image.

[Stu]

My interpretation of the question was for a cheap refractor which will perform better than the 130 on planets. Of course, there are refractors at around the $200 mark but the key thing is that they won't really outperform or match the 130.

I don't really find planetary viewing particularly rewarding below x100. Jupiter shows good detail between x150 and x180, Saturn often sustains higher mag and Mars needs more still, well over x200 if the conditions are good.

Stu