Telescope Focus Issues

[maddownunder]

A real newbie at this, so hope this ain't a really dumb question. Anyway, I got a Tasco Lumina 60mmX900 telescope as a present. Really just trying to get to grips with how it's gonna work. But I've found that so far when I try to use my 4mm eye piece or my 20 &12mm with the barlow, I run out of focus. I've wound the focus tube all the way in before I can get ojects in sharp focus. Am I doing something wrong or is it my set up or just the scope (I know it ain't no swiss watch).

[mickoking]

G,day newdownunder and welcome :thumbsup:

The problem is probably your scope, Tasco is synominous with the dreaded "department store telescopes" . One thing tho, have you tried focussing your 'scope with and with out your star diagonal? Sometimes these telescopes come into focus fine with the diagonal but not with out it. Also you may have trouble achieving sharp focus with the 4mm eyepiece, for a variety of reasons. One being the magnification is waaaaay beyong the capabilities of a 60mm achromatic refractor (x225). Generally A 60mm telescope would have a maximum effective magnification of about x120-x140.

Sorry to be a bearer of bad news but your telescope is going to strugle to be an effective astronomical telescope, many of us started of with such telescopes. I would suggest that you use your telescope with the lowest power eyepieces (20 and 12mm) and make the descision to upgrade to a more effective instrument. And by the way ask as many questions as you like, there are no dumb questions.

Cheers Micko :)

[mick pinner]

your scopes practical power (magnification) is about 120x this being approx 50x per inch of aperture. with a 4 mm ep you are trying to image at 224x which is impossible with any clarity at all. any ep under 10mm probably won't work, the smaller the ep in mm the more power and therefore the better the optical system has to be to cope. the barlow is probably poor quality and also adversely affects the view.

[maddownunder]

Thanks boys, I suspected as much that it was the scope. Just have to keep saving to upgrade to decent scope. will have to bend your ears for some advice on what would be the best thing to buy, come the time.