Go Back   IceInSpace > Equipment > Astrophotography and Imaging Equipment and Discussions

Reply
 
Thread Tools Rate Thread
  #1  
Old 15-06-2013, 06:45 AM
Astroman's Avatar
Astroman (Andrew Wall)
<><><><>

Astroman is offline
 
Join Date: Feb 2005
Location: Paralowie, South Australia
Posts: 4,348
Can we work out Telescope focal length from a Camera FOV?

Hi all,

I was wondering if it is at all possible to work out the Telescope Focal Length from an image taken with a Camera. For instance, I used the website http://nova.astrometry.net on an image I took (below). On successful completion of the image, the website tells me I have a 2.77 x 1.84 FOV with a pixel scale of 4.98 arcsec/pixel and a radius of 1.66

Given the above information and adding the other known values such as I was using a Canon 400D, and the telescope I was using has an aperture of 80mm. Can we then work out the focal length the image was taken at?

Links to the annotated images using Astrometry.net
M8 and M20

NGC 4945

Images below...
Attached Thumbnails
Click for full-size image (M8M20.jpg)
213.3 KB3 views
Click for full-size image (ngc4945ca.jpg)
195.6 KB2 views
Reply With Quote
  #2  
Old 15-06-2013, 08:07 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 6,967
Yes, there are many way's of doing it.
The simplest is probably to use the freeware CCDCalc to enter your data and do some iterations of focal length until it matches...
http://www.newastro.com/book_new/camera_app.php
(just plugged in your camera and FOV - close to 304mm focal length)
Reply With Quote
  #3  
Old 15-06-2013, 08:15 AM
cfranks (Charles)
Registered User

cfranks is offline
 
Join Date: Feb 2008
Location: Tungkillo, South Australia
Posts: 599
Focal Length (mm) = (Pixel Size (microns) / Arc sec per Pixel) * 206.3
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 09:10 PM.

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