Help with my telescope.

[Tremolo]

Hello, I've just joined after lurking for a while! Hello everyone.

I've recently purchased an Orion Observer 60 refractor that comes with two basic eyepieces. I'm quite happy with it but I want a little bit more magnification. I'm quite new to this and don't really know where to look. I'm looking for a relatively cheap barlow lens that will fit my Orion.

I shall be sticking around!

Here's a nice snap of the moon I took this very night with it!

[pvaz]

When it comes to barlows people usually recommend this one: Tal

It's standard size 1.25", so should be fine on your scope.

[Tremolo]

Hey, thanks for the link. That seems like a really resonable price. I'd like to know a few things as I haven't a clue. Firstly, which should I consider? the x3 or the x2? Also, will the image remain clear but just magnified?

thanks!

[pvaz]

That depends on what telescope and eyepieces you have.

[Tremolo]

The telescope itself is 60mm. I have both k25mm and k10mm lenses.

[pvaz]

i need the focal length value too, usually it's a value between 500 and 1200mm.

[pvaz]

Found it on orion's web site. It's 700mm.

So your current eps give you:

10mm: 700/10 = 70x

25mm: 700/25 = 28x

With a 2x barlow you'll get 140x and 56x and the 3x will give you 210x and 84x.

In the site it says the maximum usable mag for your scope is 120x so buy the 2x barlow cause the 3x will be pushing the limit too much.

[Tremolo]

Thank you very much for your help!

[Capricorn]

As the scope is 60mm dia and 700mm focal length I would say that you are getting very close to the limit of magnification that the scope will handle.

A 2x barlow and 140x will I strongly suspect give a very poor view of anything.

I know that they quote max magnification 2xObjective dia (in mm) but not long ago they said max was 1.5xObjective, and optically it is reckoned that the optimum is the same as the Objective, 60 for yours.

A 2x barlow will take you above even the most optimistic max for you scope and the addition of extra glass in the form of the barlow will add to deterioration of the image.

[pvaz]

Capricorn is right, but it's your 1st scope so if you really want more mag to look at planets and the moon go ahead.

Just keep in mind that your scope doesn't have that much aperture so it may not handle that mag as well as a larger scope. If you are still into astronomy in a few months you can upgrade for a reflector scope with 150 or 200mm still in budget prices, under 200£/$. Those can handle 300x.

[Tremolo]

Hey, thanks for the advice here. So isn't there anything lower in the Barlow range? Like 1 x or 1.5 or something? I don't really have a lot of money to spend, this telescope was an upgrade from a REALLY bad telescope that I got half a year ago. I'm very, very happy with the image quality of the Orion so I don't really want to sacrifice it's performance.

[pvaz]

Yes 1.6x are more or less common and you can use one of those safely.

The 2x barlow with the 10mm EP will only pass the theoretical limit on your scope by 20x, so it should be OK.

I did a search and found this one: GSO GSO 1.25" 2x (and 1.5x) Barlow lens

You can use it as a regular barlow for 2x, or unscrew the lens and screw it to the EP filter thread to get 1.5x. Seams nice but I never used it so I can't vouch for the quality.

[Tremolo]

That's interesting. I suppose that's kind of a safe bet as to whether or not a 2x will render the image useless or not. If so, then at least I'll have the safe 1.5 too. Thanks a lot for all the help!

[Wobbly Bob]

Bear in mind that all this magnification will be fine for the planets. For DSO's you need aperture (more light gathering). The down side to magnification IS, a dimmer view of the object (narrow FOV, more glass) plus the object will appear to move faster.

Judging by that exellant image of the Moon, I would say go for a small barlow.

[Capricorn]

If it were me I would get another eyepiece of 7 or 6.5 mm. This would give a magnification of 100 or 107. I have a 6.5 around somewhere so I know they exist, not sure about 7mm's.

Being honest I am slightly biased, I don't like adding more glass to the optical path, as in a barlow, and even if expensive it adds errors to the system so I tend to have a range of eyepieces and pick whichever depending on the magnifiaction I want.

[pvaz]

If it were me I would get another eyepiece of 7 or 6.5 mm. This would give a magnification of 100 or 107. I have a 6.5 around somewhere so I know they exist, not sure about 7mm's.

Being honest I am slightly biased, I don't like adding more glass to the optical path, as in a barlow, and even if expensive it adds errors to the system so I tend to have a range of eyepieces and pick whichever depending on the magnifiaction I want.

I'm with you 100%. I don't use my barlow. It's stored in a drawer waiting for me to star imaging planets.

My barlow adds some light scatter and I find it very annoying. But at the time I was being cheap so I got what I paid for...

[Tremolo]

Hey! Thanks for all the help again. Actually, whilst switching through my lenses I realised 'Why don't I get another lens?' So, uh...can you talk to me about lenses? Where to buy, what I should aim for etc. On my previous and very poor telescope, It came with 1.5 and 3 x barlow and at highest it was an horrifically poor image.

[pvaz]

Lots of people use barlows and they like it. I bought one that cost like 28£ and adds a lot of glare around the planets witch makes it hard to see detail.

So I bought a 9 and 5mm so I would not need it.

People using TALs and TeleVue or the Orion Shorty say they are good. I never used any other then mine witch is a Portuguese BS Astro and it SUCKS!

Next time I try to buy Portuguese made optics to help my national economy, please someone pinch me or something!

We are good at a lot of things but optics is not one of them...