Advice on processing H-alpha images with DSLR

[Wailin]

Hi all,

Probably been asked before but can't seem to find any info. As the title states, I imaged the Sadr region in Cygnus late last night with a 7nm Ha filter. My first time using such a filter I was amazed at the detail in the subs as they popped up on backyard eos. I think I have some really decent data but I am unsure as how to proceed with the stacking and processing since I use a 450D camera, not a CCD. I use nebulosity for stacking. Do I just add darks and flats as normal and stack as if it was RGB? I presume the flats and darks need to be taken with the filter in place also? Another question I have (forgive me!) is the debayering process on nebulosity, what should I do in this case with Ha images?

Apologies for all the questions, I just don't know how to proceed.

Tony

[rfdesigner]

dark, flat with the data prior to debayering. (flats need the filter, darks don't ... there's no light landing on the sensor.. so the filter has no effect)

once debayered just trash the G & B of course.. then align and stack.

Derek

[Wailin]

dark, flat with the data prior to debayering. (flats need the filter, darks don't ... there's no light landing on the sensor.. so the filter has no effect)

once debayered just trash the G & B of course.. then align and stack.

Derek

Thanks Derek. How do I discard the G & B channels before alignment?

[rfdesigner]

split from colour into 3 monochrome "r" "g" "b" frames.

In iris the command is "split_RGB", I'm not sure about other packages

Derek

[Wailin]

Thank you Derek. Got it sorted.

[Shibby]

Hi Tony,

I remember that excitement when first using an Ha filter

I can't speak for Nebulosity, but you need to disable interpolation when debayering; e.g. "super pixel" mode in DSS. This'll 1/4 the resolution but give you a proper red channel without interpolation messing it up. You could also enable 2x drizzle (if you have enough RAM to cope!) as this can help reduce the noise. It may also improve resolution but I always reduce by 50% afterwards if doing this...

I trash the G+B channels in photoshop from the stacked result.