[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: [ATM] cassegrain perforation size

To: lance clarke <atm@atmlist.net>
Subject: Re: [ATM] cassegrain perforation size
From: Richard <cnc@cncservo.co.uk>
Date: Mon, 5 Nov 2007 18:01:12 +0000
Delivered-to: atm_arc@astro.umsystem.edu
In-reply-to: <BAY140-W43F426E675C463049A96B6A8880@phx.gbl>
List-archive: <http://www.atmlist.net/pipermail/atm>
List-help: <mailto:atm-request@atmlist.net?subject=help>
List-id: The Amateur Telescope Makers List <atm.atmlist.net>
List-post: <mailto:atm@atmlist.net>
List-subscribe: <http://www.atmlist.net/mailman/listinfo.cgi/atm>, <mailto:atm-request@atmlist.net?subject=subscribe>
List-unsubscribe: <http://www.atmlist.net/mailman/listinfo.cgi/atm>, <mailto:atm-request@atmlist.net?subject=unsubscribe>
References: <BAY140-W43F426E675C463049A96B6A8880@phx.gbl>
Reply-to: Richard <cnc@cncservo.co.uk>
Sender: atm-bounces@atmlist.net

Hi lance,

Monday, November 5, 2007, 5:47:15 PM, you wrote:

lc> I'm finished hogging, and need to determine the size of my Dall-kirkham perforation.
lc> The primary is 150mm f/4, the secondary is 45mm and the effective
lc> focal length of the entire system is f/16.

Assuming a field diameter of 30mm, a back focal distance of 100mm and
mirror separation of 460mm then a 35mm diameter hole will do you. If
the back focal distance is 200mm with 440mm mirror separation then you
will need a 40mm diameter hole.

-- 

Best regards,
  Richard in the UK

_______________________________________________
ATM mailing list http://www.atmlist.net/

References:
- [ATM] cassegrain perforation size
  - From: lance clarke <alaskawolfjoe@hotmail.com>

Prev by Author: Re: [ATM] Mirror cell for an 8" mirror
Next by Author: Re: [ATM] Public Terrestrial Telescope: Focuser Materials & Lubricants?
Previous by thread: [ATM] cassegrain perforation size
Next by thread: Re: [ATM] cassegrain perforation size
Index(es):
- Author
- Thread