Help with UHC filter colour (Magenta)

[vincentnm]

Hi All,

I took this widefield of the Veil using a UHC filter and a F1.8 lens/Canon 350D. 600s exposure.

The UHC's given me a magenta background. How can I get rid of this background colour in PS? . Tried Colour Balance, Colour Replace, Levels/Curves after converting to CMYK. Nothing works really.

Anyone got a clue?

Thanks,

Vincent.

[Aza]

I loaded it up into Nebulosity and used the Adjust colour backgound setting. Not perfect but took 2 seconds.

Do you stack the subs in DSS? If so you can do this:

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......."

[Catanonia]

Sometimes I use Noels actions and LP removal. Works to an extent, but you have to be careful with it.

Also try this link out

Astrophotography Photoshop for Beginners

[roundycat]

a couple of quick observations; the lens is giving you major geometry problems at f1.8, 2.8 or 4 might be better. The exposure is much too long for f1.8.

I tackled the background colour in PS and tried to enhance some of the nebula detail that was present. I made extensive use of Curves together with numerous selections to try to reduce the gradients. Not very successfully.

Mostly I suspect the gradient problems were down to the filter not being a match for the wide view of the lens, what was the focal length? Somewhere around 20mm?

Never convert any of your pictures into CMYK, it is particularly useless for our purpose. Your filters will be RGB, your colour channels will be RGB and you printer will expect RGB.

You can just make out the Veil and the NA nebula at the top LH corner.

Dennis