Nexstar 130SLT

[lettucelord1]

Which lenses should i get for my Nexstar 130 SLT please? It came witha 9mm and 25mm . I am thinking I should invest in a mid priced x2 Barlow , but have no idea how much to pay or what brands. it is an F5 scope

Thank you

Adam

[jambouk]

Hi,

Remember your maximum magnification will be 50 x aperture (in inches) so for you:

5 x 50 = 250x magnification (but i suspect even this will be too far too much magnification), see:

http://starizona.com/acb/basics/equip_magnification.aspx

Magnification = focal length of the telescope divided by focal length of the eye piece. So for you:

650 mm / 9 mm = 72x magnification

650 mm / 25 mm = 26x magnification

Add a 2x Barlow:

650 mm / 9 mm * 2 = 142x magnification

650 mm / 25 mm * 2 = 52x magnification

So a Barlow does open up the range of magnifications offered by your two eye pieces.

However, most stock eye pieces are pretty poor, and adding a Barlow to them, unless the object is very bright like the moon, degrades and dims the image greatly.

So, i think you'd be better off getting a better eye piece or two, and sticking at the magnification they'd give you. Find a nice 8-10mm eye piece would be my advice, but it depends how much you've got left to spend.

James

[Kirscovitch]

I am quite new myself and have the same scope. I have purchased a 2x barlow as my main first purchase. I figure that down the road it will give a lot of different variations to the eyepieces you acquire. Also I went kind of crazy and purchased a 3mm Zhumell EP. That's about 216x and I plan to use it for planets. I also am thinking about a 5mm lens. Don't take my advice for new but I figure with a 25, 9, 5, and 3 that I should have a fairly decent start. Would like something in the 30mm range too. Just my 2 cents.

[jambouk]

It's a shame no one else has chipped in yet with their advice/opinion.

Kirscovitch, i think you will struggle to get good views with the 3mm eye piece. I suspect you'll find the 5mm will give clearer, brighter views of jupiter. But do report back. This is all useful stuff to feed back to other people with the same kit and aspirations.

James

[Kirscovitch]

Thanks James. You're most likely right but I'm gonna give her a whirl anyway lol. I intend to try out all sorts of combinations to get a feel for what my scope can and can't do. If It turns out that the 3mm gives me a hard time with my setup, it can always wait till I get a better setup. (Just don't tell the gf) lol

[lettucelord1]

Many thanks folks!

Any suggestions on brands? I I have read a review from a scientist at Jodrill Bank  who used aTelevue X2 Barlow with my type of scope. These are about £93 .

Adam

Leicestershire UK

[brantuk]

I've pm'd you Lettuce - welcome to SGL

[jambouk]

There is a thread somewhere recently about barlows and powermates. Have a hunt for it.

If you are in leicester you should catch up with us east midlands stargazers; i'm just up the road in nottingham, and brantuk is even closer to you. We are a cheery bunch and try to get together for observing sessions and meetings for talks and the like.

James