Scope EP mag. V. Astro EP mag. (1 Viewer)

Musoman

PETE - Nikon/Sony Shooter

• Sep 19, 2010

• #1

Can anyone tell me how Scope EP's match up equally ( in magnification ) to an Astro EP ?

Astro EP's seem to be measured in millimetres ( 5mm, 10mm, 15mm, 20mm, etc ) rather than the X of Scope EP's.

So for instance, if you have a 30x Scope EP, whats the equivalent in an Astro EP , would it be 30mm ?

 

S

Steven Astley

Well-known member

• Sep 19, 2010

• #2

The magnification depends on the focal length of the telescope aswell as the eyepiece

Magnification=focal length of scope/focal length of eyepiece
which means

focal length of eyepiece=focal length of scope/magnification

So for a 500mm scope a 30x eyepiece would have focal length of around 17mm

 

Musoman

PETE - Nikon/Sony Shooter

• Sep 19, 2010

• #3

Can you do all that again with 420mm + 24x scope EP Steve ? Cheers

It seems to work out very similar ...17mm approx

So a 17mm Astro EP on 420mm scope, would be equiv. to 24x Scope EP on the same 420mm scope ( i think )

 

Last edited: Sep 19, 2010

S

Steven Astley

Well-known member

• Sep 19, 2010

• #4

Musoman said:

Can you do all that again with 420mm + 24x scope EP Steve ? Cheers

It seems to work out very similar ...17mm approx

So a 17mm Astro EP on 420mm scope, would be equiv. to 24x Scope EP on the same 420mm scope ( i think )

Click to expand...

Yep, moreorless. Thats why nikon eyepieces have different mags on different scopes.

 

Musoman

PETE - Nikon/Sony Shooter

• Sep 19, 2010

• #5

Noted.

I think Paul actually said the same thing, only i didnt realise it till now. My maths isnt the best

 

alphan

Well-known member

• Sep 20, 2010

• #6

Most scope EP have a few X # on their EP. Does that refer to specific scope FL only? Does spotting scope have a very limited choice of FL?