My First HaRGB - Orion

[Knight of Clear Skies]

Had a go at blending my Ha shot of Orion into an RGB image from November 2014. I used Photoshop to blend in the Ha in the red channel, using lighten mode so that it only adds signal where the Ha is brighter (think that might have been an Olly tip in a thread I read somewhere).

It's a partial success, it's brought out more of the Loop and Angelfish but there are a few artifacts where I couldn't get the image to align perfectly. I'm not sure if I did something wrong or if the distortion in the two shots is preventing it. They were taken with two different 50mm lenses at different focal ratios, and in different orientations. There is also a red background where the two frames don't line up. For comparison, here's the original RGB image.

A worthwhile experiment but I prefer the plain Ha image.

[SyedT]

Wow, that is stunning! The cloud complex looks fantastic; a job really well done!

[ollypenrice]

Do you have Registar for the co-registration of the two images? If not you could Dropbox me the TIFFS and I'll do it for you and return them. Just PM me.

It looks as if there's quite a bit of rotation between RGB and Ha though.

I do add Ha as you suggest. I got that from Rob Gendler's website some time ago. While the Ha is pasted over red in blend mode lighten there is nothing to stop you from manipulating it in situ to see what the effects are. For example, if the whole background is being lightened you can pull the Ha down at the very bottom in Curves but, to get more effect higher up the brightness, you can then lift the curve around the middle. In a nutshell you are not obliged to work with the Ha as it was pasted onto red, you can persuade it to do what you want once it's there!

Olly

[Knight of Clear Skies]

Thanks for the offer and the tips Olly. I've saved the layers in PS so I'll have another go at aligning and see what adjusting the curves does to the image (on-the-fly preview is definitely a strength of PS). I don't have Registar at the moment but I'll probably need it if I start doing more HaRGB images. I've just joined the 1600MMCool crowd but it's awaiting first astronomical light, I'm thinking about a 3nm Ha filter to go with it.

[ollypenrice]

Just now, Knight of Clear Skies said:

Thanks for the offer and the tips Olly. I've saved the layers in PS so I'll have another go at aligning and see what adjusting the curves does to the image (on-the-fly preview is definitely a strength of PS). I don't have Registar at the moment but I'll probably need it if I start doing more HaRGB images. I've just joined the 1600MMCool crowd but it's awaiting first astronomical light, I'm thinking about a 3nm Ha filter to go with it.

Stop thinking and spend!!!! Great, great filter.

Olly