First ever RGB image and I'm struggling

[swag72]

I have got data for my first ever RGB image - I took it last night and my hope was to add it to my Sh2-235 data so that I could colourise the image.

My Ha subs were all taken at 600s unbinned. Last night I took RGB subs, 15x 300s unbinned for each filter. What I am finding during processing the RGB is that I have totally lost star colour. That suggests to me that the subs were too long, yet in the nebula, there is little colour in there.

So, how do I go about deciding what is the best time for RGB subs? I thought from my reading and searching that 300s would be fine, but clearly it's too much for stars and not enough for the nebula. I just want to keep it simple at the minute and not try anything too fancy.

In my individual RGB subs, I could feintly see the nebula in the red channel, but in the green and blue only stars. That was kind of what I was expecting. Interesting there's also massive gradients in the RGB data, while in the Ha there was none at all.

Would welcome your thoughts on this as I try to progress to a colour image.

[swag72]

Folks, I think I MAY have found the problem.

I took RGB images last night and tonight when I have just come out to the obs, my filter is in the green position. That suggests to me that last night I only took R and G and then combined more G into the blue channel, when I really forgot to move the filter round.

MAYBE!!

[MG1]

D'oh easily done when trying to plan it all out.

Have a glass of wine and relax over Christmas...the progress you've made has been amazing so 2012 is def going to be a great year.

Best wishes and thanks for all your questions, many of which have raised some interesting points for us all.

Merry Christmas Sara

[ollypenrice]

Yup, done that. Once? No. Twice? No, worse than that...

Your subs cannot possibly be too long at the f ratio of your scope. You could double it and be OK on almost all targets, but I wouldn't. 5 mins should be fine.

Happy Christmas! I'm shooting flats on Xmas eve. I'm a NERD!!! Drinking quite a lot though...

Olly

[swag72]

Cheers to you both!!

@MG1 - There will be loads more silly questions in 2012, so watch this space!!

@Olly - Glad I'm not the only one!! You say about the subs not being too long, yet when I check the individual subs I am still getting stars with cores at the max ADU. Will they still have colour? Perhaps they are white stars?!!!

[ollypenrice]

Cheers to you both!!

@MG1 - There will be loads more silly questions in 2012, so watch this space!!

@Olly - Glad I'm not the only one!! You say about the subs not being too long, yet when I check the individual subs I am still getting stars with cores at the max ADU. Will they still have colour? Perhaps they are white stars?!!!

They will round the edges. You could shoot some RGB shorts and paste these underneath, then erase the stellar cores from the long stack on top. There's a Martin B tutorial on how to select stars only. Or you could use Noel's Actions, Increase Star Colour. Or you could do this: paste a copy of the core-burned image underneath. Blur it and increase the saturation, so spreading colour around the star cores. Then just erase the star centres from the top image.

Olly