#1  
Old 30-08-2008, 07:18 PM
PeterO's Avatar
PeterO
Registered User

PeterO is offline
 
Join Date: Jul 2005
Location: Traralgon Vic
Posts: 129
Analyze This Vigneting

Hey all,

Pic below is a Flat through the scope, I,m assuming this to be vigneting, is there anything I can do about this?.

Details are 8" F4 newt taken with a 400d and Baader mpcc, I had to move the primary mirror up the tube by about 16mm and use a low profile focuser to achieve focus with the camera. any ideas or help would be nice.
The image has been stretched a far bit to make it more apparent.
Peter
Attached Thumbnails
Click for full-size image (BINT_MasterFlat_1 (Medium).jpg)
11.1 KB34 views

Last edited by PeterO; 30-08-2008 at 09:52 PM. Reason: more info
Reply With Quote
  #2  
Old 30-08-2008, 09:01 PM
Ian Robinson
Registered User

Ian Robinson is offline
 
Join Date: Jan 2007
Location: Gateshead
Posts: 2,205
Get a lower profile focusor and a bigger diagonal ?

The draw tube is too long.
The draw tube is so long it is stopping some of the light from the secondary from reaching the focus plane of the camera.
A bigger diagonal will ensure full illuminations of the fov (no drop off).

You should have moved the primary rather than secondary.

Last edited by Ian Robinson; 30-08-2008 at 09:15 PM.
Reply With Quote
  #3  
Old 30-08-2008, 10:12 PM
Astrod00d's Avatar
Astrod00d
Lost In SPace

Astrod00d is offline
 
Join Date: Aug 2007
Location: Sydney, Australia
Posts: 218
Moving the main mirror up the tube would increase the size of the light cone at the secondary. The secondary may be too small to illuminate the entire field. The 400d sensor is quite large.
Also the illumnation does not seem to be centered. Is the scope precisely collimated? I read somewhere that these f4 newts are very fussy about collimation.

Cheers,

Rob
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 04:48 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
OzScopes Authorised Dealer
Advertisement
Meade Australia
Advertisement
Celestron Australia
Advertisement
Bintel
Advertisement
SkyWatcher Australia
Advertisement
NexDome Observatories
Advertisement
Lunatico Astronomical
Advertisement
Astronomy and Electronics Centre
Advertisement