Magnification

[Brett]

Could someone explain to me what magnification I can get out of my scope, a 130p with a 650 focal length. I have a 25mm, 10mm, 15mm, 9mm and finally a 6.3mm. I also have a 2x Barlow

Thanks

Brett

[Merlin66]

The formula for magnification is:

Magnification= focal length of the primary/ focal length of the eyepiece.

So for your telescope (fl=650mm) and the various eyepieces:

25mm x26

15mm x43

10mm x65

9mm x72

6.3mm x103

When used with the x2 barlow the magnification would be doubled ie the 10mm would give x130.

Hope this helps.

Ken

[jgs001]

Brett, the accepted usable magnification is considered to be about 2x the aperture in mm... so in your case x260... To calculate the magnification use this calculation

magnification = FL Scope/ FL ep...

so for example, the 15mm eyepiece...

650/15 = 43x

The 2x barlow acts as if to double the focal length of the scope (or halve the focal length of the ep... the effect is the same so it doesn't matter to much...)

so for the same ep...

(650x2)/15 = 87x

You have with those ep's (with barlow)

25 = 26x (52x)

15 = 43x (86x)

10 = 65x (130x)

9 = 72x (144X)

6.3 = 103x (206x)

To go to the higher magnifications, it's better to start low and build up, recentering as you go. You'll probably also need to refocus when you change ep too.

HTH

Beaten ... must learn to type faster

[Brett]

Cheers for the help I had a rough idea but wasn't 100% sure.

Thanks

Brett

[LukeSkywatcher]

I have a scope with similar specs and i have pushed the magnification as far as i can with my smallest EP (6mm) and 2x barlow (which gives a magnification of 216X). It handles it pretty well. I have also stacked two 2x barlows+6mm EP (432X) but i think that is pushing the scope beyond its ability.

I'm going out on a limb here by saying that i think a scope of this size could actually use a 3x barlow.

I wasnt brave enough to buy a TAL 3x barlow for the scope. But i can imagine it working.