to( tom a) my scope is a startravel 120 f600 + 10mm 25mm & x2barlow lense?

Answer 1

Thank you. You could have added to your previous question, though : )

Others will know more than me about medium-length refractors. But I expect that this sort of scope is good for wide field views of the sky, as well as viewing planets and splitting doubles, provided it has good optics.

The magnifications are as campbelp says, so it depends on what you want to see. If you're looking at the moon and planets, you start on low power (the 25mm ep), then increase for more detailed views using the barlow or the 10mm. If you're interested in splitting close multiple stars, then do the same.

For deep-sky objects, like open clusters and nebulae, you'd generally use the widest field you have, which is the 25mm. For some objects, you could increase the magnification then, but that also makes the field of view narrrower.

Get a good book of star maps to know the sky a bit, too. Nightwatch by Terence Dickinson is a good guide.

Answer 2

Magnification is focal length of objective divided by focal length of eyepiece. So a 600mm focal length telescope with a 10mm eyepiece gives 60 power. The 25mm eyepiece would give 24 power. The x2 Barlow just doubles the magnification, so 10mm + Barlow is 120 power and 25mm + Barlow is 48 power.

Answer 3

And your question is ................?