Image of the day

Captured by
John Roach

Enhanced Uranus showing Polar Cap and possible Aurora

About Astromart

My Account

New to Astromart?

Register an account...

Need Help?

Focuser size

Started by scottw, 03/13/2009 06:39PM
Post Reply
Posted 03/13/2009 06:39PM Opening Post
Scott Anderson
View public profile Send a private message to Scott Anderson Find more posts by Scott Anderson Find threads started by Scott Anderson
Forum Member

Join Date: Oct 2003

Location: Addison NY, US

Posts: 61

Hello,
I have a newish Orion reflector andthe focuser tube is around 1.638" inside diameter. What is this for?

Scott
Quote
Posted 03/14/2009 04:12AM | Edited 03/14/2009 04:13AM #1
Michael Minnhaar
View public profile Send a private message to Michael Minnhaar Find more posts by Michael Minnhaar Find threads started by Michael Minnhaar
Forum Member

Join Date: Jul 2005

Location: Portland OR, US

Posts: 57

The drawtube diameter quite often is larger than the eyepiece to avoid vignetting and/or to allow proper baffling. You will use an adaper or eyepiece holder to step this down and hold the diagonal or eyepiece.
Vixen uses 41mm ID/43 mm OD with M43x0.5 male thread for 1.25" and 58mm ID / 60mm OD with M58x0.5 female tread drawtubes for 2" eyepieces. Many focuser to day still use these sizes.

Michael
Quote
Post Reply

Funding Member

Sponsors


View all sponsors

Search