ETX-125 Max EP

[oshb5]

Hi All

Now i have this scope And I have 3 EP.s at the moment a 25 , 17, and a 10 so am in the market for a few more I know i need something of larger dia like say a 40 But what I was wondering is what is the smallest it can use that would not take it over and start to blur the image i.e. something just before the limit of the scope and my eyes LOL.

I also a a good quality 3x Barlow but reading it will not be much use with the ETX apart from possibly Luna viewing

So rearly im looking for suggestions as to how far i can go with out wasting money on a EP that is past the limit of the scope and spending time trying to focus it in,,?

regs Andy

[brianb]

The 10mm you already have is too much. Optimum high magnification is approx. 12.5mm with your f/15 scope.

[John]

As Brian says, I think your 10mm eyepiece will deliver the maximum magnification your scope can usefully deliver, and then it would have to be a night of good vieving conditions to make use of that so a 12.5mm / 13mm eyepiece would be a more useful purchase. At the other end of the scale a 32mm, rather than a 40mm, in the 1.25" fitting, delivers the maximum true field of view - the 40mm shows no more and has a rather narrower, tube-like, apparent field.

[brianb]

At the other end of the scale a 32mm, rather than a 40mm, in the 1.25" fitting, delivers the maximum true field of view - the 40mm shows no more

True but that's not the whole story ... you get more apparent contrast with a lower power. If you already have a 25mm it's hardly worth going for the 32, go straight for the 40.

[John]

True but that's not the whole story ... you get more apparent contrast with a lower power. If you already have a 25mm it's hardly worth going for the 32, go straight for the 40.

If you like, but I find the views through a 1.25" 40mm tube-like and unsatisfying.