Stupid eye piece questions

[Briddo]

Okay folks here are a couple of more really stupid questions about eye pieces.

I'm going to buy a couple of new eyepieces for my Celestron Astromaster 130 eq and I think I have confused my self so now need to ask some advice. Sorry in advance for my stupidity:confused:

Does the smaller "mm" on an eyepiece mean it has greater magnification? So a 10mm eyepiece has greater magnification than a 30mm one?

Can someone explain why some eyepieces are referred to as "low power" and others "highpower" ??

Hope someone can help an idiot.

Jan

[brantuk]

Yup - you have the principal correct. If your scope has a focal length of say 600mm then a 20mm eyepiece will give you 30x magnification. A 10mm eyepiece will take it up to 60x mag and therefore a higher power. Just divide the ep size into the focal length

Try not to go above 200x mag. UK seeing isn't usually good enough to support higher powers. 150x to 180x is a comfortable maximum. Also bear in mind the highest practical limit in the ota specs - often over stated so not a good idea to go anywhere near the maximum

[John]

Yes, the smaller number of mm (thats the focal length of the eyepiece) the greater the magnification you get.

It's useful to have eyepieces that give low, medium and high magnifications with your scope because different objects have different needs.

Low power is something around 25x - 50x and high power, in your scope, would be 150x or so. High power is useful for the moon, planets and binary stars. Low or medium power is useful for deep sky objects. Some deep sky objects are pretty large (eg: the Andromeda Galaxy is 3x the diameter of the full moon) so low power is best for looking at those.

[Zul]

Yes 10mm eyepiece will give more magnification than 30mm. You can count simply what magnification will be for example mine telescope focal length is 500mm and i put 10mm eyepiece 500mm/10mm=50x magnification etc. 500mm/4mm=125x.

[Orion_the_Hunter]

This SGL guide http://stargazerslounge.com/beginners-help-advice/80772-eyepieces-very-least-you-need.html will tell you everything you need to know.

[Briddo]

Thank you very much indeed I now understand.

You are such wonderful people.

Jan

[solo]

Jan, you could also get youself a x2 Barlow lense as well which effectively doubles your eyepiece collection. You put this into your focusser and then your eyepiece into that. This doubles the magnification of the eyepiece. Hope I haven't confused you.

[Briddo]

Thanks folks. I have got the focal length of the telescope and have had another look at the link posted by Orion the hunter and it now makes sense.

I'm not really totally stupid (at least I don't think so!) I'm just trying to adjust my photography head to a telescope/astronomy head!

Thanks Solo I get the principle of a Barlow lens so added one to my shopping list at least they are not as expensive as camera lenses!

[John]

... I get the principle of a Barlow lens so added one to my shopping list at least they are not as expensive as camera lenses!

The TAL 2x barlow is the best quality of the lower costs ones - about £35.00 each.

Beware though, really good quality eyepieces / barlows can easily get as expensive as camera lenses

[Tinker1947]

There are EP's that allow camera to be attached, i have ordered a baader-hyperion-68-degree-eyepiece from FLO with a T-Adapter, as your into Photography these might be of interest.