How do you get the red out..?

[Astro Nut]

Gordon,

Reason I ask is, Nebulosity has an option to correct the white balance for "modified" DSLR's. This automatically takes care of 99% of the reds problem during the pre-processing stage.

I'm using Nebulosity 2 and I too have a red problems with my modded-DSLR images, any chance you can forward the pathway to this feature in Nebulosity, and any tips when using it?

Also, when trying to get the red out, does this feature, or any other processing technique leave the nebula gains one gets by using a modded camera?

Seem like I've been losing fine details in objects when I reduce the red.

Thanks,

Rich

[ghswen]

Hi Rich,

Go to "Edit / preferences" and change the item shown in the attached screen print.

That should help correct the problem. Note that you will still have to tweek the colors a bit in post processing but it clears up quite a bit of the problem on the pre processing.

[Astro Nut]

Thanks for your response Gordon.

Sorry if I'm badgering this point, but I'm sure using this feature in Nebulosity will reduce the red, but do you feel it reduces the extra detail that one gains by using a modded camera in the first place?

Using other techniques, I've tried getting rid of reds in other images, but have also lost a lot of fine detail that I modded my Canon for in the first place.

Thanks again,

Rich

[KeithBC]

In DSS, I set my red level to 0.75 of the green and blue level. I also selected the auto white balance feature. To be honest, I don't know if these two features work together, or if the auto balance is overriding the 0.75 factor, but the combination takes care of the white balance extremely satisfactorily. On the DSS histogram, the three colour curves come out perfectly synchronized, and I don't have any problem getting a pleasing colour balance in GIMP or Paint.Net. I used to have a terrible time getting the red balanced before I found these settings.
Untitled.png

[ghswen]

Not really. Since the process to correct the white balance takes place during the debayering process all the detail should remain. Keep in mind what you are correcting is the "over correction" for the red channel. The problem with a un-modified camera is that is can't capture near enough red in the first place.

I'm sure buried deep in the setup for DSS there is a setting for a modified camera, I just don't use it so can't really say for sure.

The problem with correcting 'after the fact' is all of the detail is in place and somethings are going to be adjusted that could reduce the details you want to keep. That's why it's better to have the process take place earlier rather than later.

edit: Looks like Keith got his post in before mine! Thanks for the info Keith, I was sure DSS had a way to adjust for it!

[Astronewb]

In DSS, I set my red level to 0.75 of the green and blue level. I also selected the auto white balance feature. To be honest, I don't know if these two features work together, or if the auto balance is overriding the 0.75 factor, but the combination takes care of the white balance extremely satisfactorily. On the DSS histogram, the three colour curves come out perfectly synchronized, and I don't have any problem getting a pleasing colour balance in GIMP or Paint.Net. I used to have a terrible timer he red getting the red balanced before I found these settings.
Untitled.png

Thanks Keith, I haven't stacked any of the images in DSS yet, so I was wondering if I could just adjust the RBG sliders to reduce the red. Your method seems a bit more repeatable. I'm going to stack a few tomorrow as usual, and then stack the same with the settings adjusted, and see where it winds up.

Best, Paul

[dibia]

Try shooting with a Custom White Balance. In PS the RGB channels can be adjusted in Levels. Color balance could also be tweaked.

Clem

QUOTE=Astronewb;1057515882]Hi, attached is a single 240 sec image, (Cave Nebula) taken with my Nikon D5100. Just got it back from being modified for full spectrum and Ha. I have about 30 mins of exposures I'm waiting to stack. Just wanted to hear from modified camera users on the best way to eliminate the red halos around the stars and reduce the overall red cast in the image?



I did some quick stretching and processing in PS to make it presentable.

ISO 400, 240 secs, Baader SkyGlow filter. iEQ45, guided w/mini Borg 50 and SSAG. 15 Jul 2012.

Thanks in advance,

Paul[/QUOTE]

[Astronewb]

Thanks Clem, I shoot in RAW, so the camera white balance doesn't effect it, Jpg's are fine with a gray card white balance. Will try the PS settings as well.

Clear skies,

Paul

[Astro Nut]

Paul,

I was wondering if I could just adjust the RBG sliders to reduce the red

I tried this myself and I lost a lot of the nebulosity I tried to capture with a modded cam.

Try it yourself...take the red sliders to the extremes in either direction and you'll see what I mean.

Rich