White balance problem with CLS filter

[michaelmorris]

Help needed please.

I'm still pretty new to DSO imaging with my new Canon 1000D (unmodded). I'm using DeepSkyStacker (DSS) for alignment and stacking. After a fair bit of experimentation and asking about, I've worked out that using the camera white balance settings in RAW settings options in DSS gives a good colour balance. However, I've started using a CLS clip filter now and find that all my images turn out red. The camera is set to Auto White Balance (AWB) during exposures.

I have a number of questions.

1) Is there a way of preventing this happening in future? Would setting a custom white balance for the CLS filter on the camera work?

2) Is there a way of automatically or manually compensation for the incorrect white balance on my existing RAW images in DSS prior to stacking?

3) Is there a way of resetting to a correct white balance for images that have already been through DSS? I’ve tried auto levels in Photoshop but this doesn’t make of a difference.

Thanks

[Aza]

This fixes the balance perfect for me while stacking in DSS:

After clicking 'Stack checked pictures' in DSS, click recommended settings.

In that section you can scroll down and ensure you use the option that says:

"If the colour balance in the resulting image is hard to fix......."

If I have to colour balance after DSS, I use a function in Nebulosity. I find it easier to have it done for me, rather than trying by eye!

[michaelmorris]

This fixes the balance perfect for me while stacking in DSS:

After clicking 'Stack checked pictures' in DSS, click recommended settings.

In that section you can scroll down and ensure you use the option that says:

"If the colour balance in the resulting image is hard to fix......."

If I have to colour balance after DSS, I use a function in Nebulosity. I find it easier to have it done for me, rather than trying by eye!

Thanks for the tip, I'll give it a try (It's running now). What is the function you use in Nebulosity?

[Aza]

I use Neb when I dont want to restack, or playing with someone elses image etc.

Click IMAGE > ADJUST COLOUR BACKGROUND (OFFSET)

[michaelmorris]

Right - progress. I've tried various procedures suggested by Arran in this thread and by others in http://stargazerslounge.com/imaging-image-processing-help-techniques/88368-colour-correcting-lp-filter.html and made no progress at all. In fact some of their suggestions made matters worse!

On a hunch, I tried stacking the light frames only, no darks. Bingo, the overall red cast has instantly gone!

My guess is that some stray light is entering the lens cap and, because the CLS filter is in place the camera is producing ever so slightly coloured dark frames. (Just a theory). Now all I have to do is work out how to fix the dark frames problem!

[Beyond_Vision]

Light could be leaking in through the view finder cover the whole camera while taking the darks.

Regards

Kevin

[michaelmorris]

My Canon 1000D didn't come with a viewfinder cover. Where can I get one? What do others use? (I thought of putting a black cloth over the camera, but am worried this will retain heat and hence lead to increased noise. Are these concerns justified?)

[Neil I]

Hi Michael

You should have had a little black rubber thing (technical term:D) fitted on the camera strap. Unclip the viewfinder surround and fit this over the viewfinder opening.

Cheers

Neil

[michaelmorris]

Hi Michael

You should have had a little black rubber thing (technical term:D) fitted on the camera strap. Unclip the viewfinder surround and fit this over the viewfinder opening.

Not on mine.

[Psychobilly]

Insulating tape...

My 1000D came with the viewfinder cover but they are fiddly little blighters especially in the dark...

[jgs001]

Peter, they're fiddly little blighters to fit when you can see what you're doing ...