Upgrading.

[shorty]

Hello all,

I am new to this site and would like some advice please. I started using telescopes 8 years ago with the Meade DS4504 that has given good service over the years as I upgraded the eyepiece adaptor to 1.25". I found it necessary last year to upgrade so bought Celestron C8-NGT last August and I am looking to upgrade my current oculars. The ones I currently have are, I think TALs that I purchase after the DS4504 however at higher mags the performance drops of. I am therefore looking to upgrade as looking through the C8 using the 7.5mm, Mars and Jupiter are difficult to resolve.

1. Are the Celestron Omni plossl's or the X-cel's going to improve matters.

2. Has anyone had any experience of Opticstar new PL 131 as reading the net the former 130 did not have good right ups.

Thanks in anticipation

Jeff

[Chris H]

In your C8 the 7.5mm eyepiece provides x133 mag so at that magnification unless your collimation is way off you should be getting some decent views, so your probably right it may be your eyepieces. The X-cel plossl's have a 50 degree FOV but with your scope having tracking they should be fine. I'd check that collimation though before you spend any money.

[AndyH]

To be honest, if you're using Tal Plossl's, the eyepieces you mention, won't show a marked improvement. The Tal's have pretty good glass in their plossl range, IMHO.

Firstly, I'd check the scopes mirror collimation if I were you.

Then, perhaps look at a better 6 or 7mm eyepiece(gives 167x and 143x). Plossls at that size, can be uncomfortable to use for some. Perhaps look into getting one with better eyerelief?

Cheers,

Andy.

[shorty]

Thanks for the advice. The other night I was looking at Mars through the 7.5mm and although one side was in focus the other was fuzzy and elongated, thats what made me think it might be the eyepiece but will check the collimation first.

[John]

Thanks for the advice. The other night I was looking at Mars through the 7.5mm and although one side was in focus the other was fuzzy and elongated, thats what made me think it might be the eyepiece but will check the collimation first.

That sort of effect can be caused by currents of warm air still in your tube if the scope has not fully cooled yet. But do check your collimation as well though.

[shorty]

Cheers John,

The scope had been outside for about 1.5 hours before using so will check collimation. I have the cheshire eyepiece, whats the best way to use this.

Thanks

[Chris H]

Have you read Astro Baby's guide to collimation? It is excellent and very easy to follow and concentrates on using a cheshire eyepiece. Google Astro Baby and visit her web site.

[Rusty Strings]

I agree, astro baby's collimation guide is the best I've seen.

John