It is currently Sun Aug 19, 2018 7:28 am


Post new topic Reply to topic  [ 1 post ] 
Author Message
PostPosted: Mon Sep 14, 2015 8:39 pm 
Offline

Joined: Fri Dec 10, 2004 10:34 pm
Posts: 287
Location: Surrey
DSLR cameras allow you to manually select the colour temperature of the light source when an image is taken as well as leaving the camera to decide for itself (auto) setting. What I am trying to find out is what is the best or correct colour temperature to use for each type of astronomical object. When you select a 'low' temperature the red sensitivity is reduced relative to the blue. If you select a high colour temperature the opposite happens and the blue sensitivity is reduced relative to the red. If you use a low colour temperature you can reduce the red/orange light pollution in images but this will also reduce the red (H-alpha) sensitivity.

This really applies if you save your images in JPG as this reduction in sensitivity takes place before the image file is written and presumably cannot be undone. It is less of a problem if you take RAW images as at least for Canon Cameras you can adjust the colour temperature of the RAW image prior to saving it as a JPG or TIFF.

The forthcoming lunar ecllipse is one place where this is very important as I suspect the 'auto' setting may decide the image is 'red' and therefore low temperature so it will use a lower colour temperature and thus eliminate some if not all of the predicted red colour. I have never seen this topic in any DSLR imaging articles or books.

Does anyone have any experiance or comments or are you willing to tell us all what you do ?

In my case I tend to use a low colour temperature for thins like Meteors and NLC to try to cut the light pollution out but quite often forget and leave the camera on 'auto'.

Good imaging

_________________
Engineer @ Work - Astronomer @ Play


Top
 Profile Send private message  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 1 post ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group