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barlow basics

Started by Plantsir, 10/28/2017 05:52AM
Posted 10/28/2017 05:52AM Opening Post
I am new to telescope ownership, I have a 6" Newtonian , hand made unit in a sonotube. I use 1.25" celestron eyepieces and others. I have found tons of cool stuff, I am happy with the overall capabilities but as with all telescope owners I want bigger, clearer, further ............. Can I add barlows ?
Posted 11/01/2017 09:04PM #1
Hi Chris,

It would help us to help you if we knew a couple more details about your Celestron Eyepieces: What focal length(s) of eyepieces do you have that you might want to use with a Barlow ?

For example: if you have a 24mm eyepiece, a 2x barlow will make it seem like a 12 mm eyepiece. And it follows that a 32mm eyepiece would work like a 16mm eyepiece with the same 2x Barlow.

Posted 11/01/2017 09:31PM #2
Hi again Chris,

It would also help us to help you if we knew either the "f ratio" of your 6 inch Newtonian or the "focal length" of the scope. For example: if your scope is an f5 then the focal length is 6" x 5 = 30" or in mm that becomes 152mm x 5 = 760mm, so a barlow would make that 760mm x 2 = 1520mm and then you could compute the "power" of the combination of the scope and eyepiece combination (and perhaps a barlow too).