Can you do it?

[Shelster1973]

Very quick question...can you combine Ha and an L image in some way to get a false colour image?

Only askingas that is all I have to go on with my new CCD at present so was wondering if I am just going to be stuck with the mono images for Ha and L or can I combine them and do some withchcraft magic on them

[vlaiv]

Well yes you can, but I don't know if results will be pleasing and it will be witchcraft indeed

Shoot things that you know are composed primarily out of Ha and some other emission line like OIII. Subtract Ha from Lum to get other component. Use such three channels to create two tone composite (Ha, OIII and Lum).

Reasoning being: if object is emitting bulk of its light in Ha and OIII then Lum will in effect be Ha + OIII, there fore Ha - Lum = OIII.

You must insure that you calibrate your frames properly: Scale them so that feature that is Ha only has same value in Ha and Lum exposure / stack. Stars will look funny colored so I guess it is best to make them white.

[MattJenko]

Sara has done some lovely images using single channels, and has done a very nice article about it : http://swagastro.weebly.com/artistic-one-channel-processing.html