Two peak Histogram - why ?

[AlistairW]

Hello,

I have been trying out a new DSLRich has a Baader BCF and a CLS CCD filter. I took a simple series of Andormedia of 30s lights, and stacked in DSS with RGB aligned. What I got back when I open the TIFF in photoshop was a picture with a purple hue to it. The histogram was like a camel, -e R and G were roughly in the same place but the bluewas shifted by a good cm (on my screen) to the right - it basically looked like a camel hump. The effect being a very blue dominated colour. Is this normal ? - The histogram certainly didn't look like ones I had done before, - any ideas what might have caused this ?

Thanks

Alistair

[AlistairW]

Maybe I need to do this ?

http://awesomeastronomy.com/tutorials/dso-astrophotography/61-aligning-rgb-channels

[PhotoGav]

That will be the CLS filter that is causing the colour cast. Yes, you can realign the colour channel peaks in Photoshop and it should balance the colours. Good luck with that, I always found it quite tricky to sort out the CLS colour cast, but there are plenty of people who swear by them, so it must be more than possible!

[PeterCPC]

You can align the colour channels in DSS as well.

Peter

[AlistairW]

Right - interesting - i was not aware of this colour cast. Infact what I will do is take a series of subs without the filter to prove to myself that is what is causing this. Thanks for the help.

[wxsatuser]

It's normal unless you use a custom white balance.

As above, aligning the channels in DSS normally does the trick.

Here is mine with daylight WB.

Edited February 19, 2016 by wxsatuser