Focal length

[todd8137]

Hi all sat here with a friend and we both have diferent ideas about working the focal lenght of a reflector scope see pic below

A =the whole lenght of the tube ?

B =from bottom of tube to the focuser

Thanks in advance.

Pat

[JED-E3]

It's from the top of the primary mirror to where the eyepiece sits in the focuser so you have to allow for the sideways distance from the secondary mirror to the eyepiece too.

[todd8137]

Thanks problem solved

Pat

[Floater]

How encouraging. A straightforward answer to a question.

Power to you Jed.

[todd8137]

How encouraging. A straightforward answer to a question.

Power to you Jed.

That's one of the great aspects of SGL ,ask a Qs that may have been asked a million times and it's always answered ,the mass knowledge of every one makes any Qs answerable ,most Qs I have asked have been answered with in ten minutes after 4 years I can now even answer some my self through the knowledge of others

Pat

[Moonshane]

yep. what he said.

[Floater]

Mind you, if the Q falls into the 'what should I spend my money on' or 'what's the best ...?', look out for lots of head scratching and lots of different views!

[todd8137]

Scopes should really be a personel choice I try and avoid telling people what to buy in case they are disappointed

Pat

[Floater]

How wise, Pat. How wise.

Still, I have found the opinions of people with wider, deeper experience contribute to the mix when trying to learn.

So don't be too reticent to share your thoughts. Newbies like me need a guiding light more often than not ...

[todd8137]

Looking at your sig you have some great eye pieces,with astronomy there's some thing new to learn every day

Pat