Dealing with hydrogen Alpha

Also, when processing the hydrogen Alpha Subs do I not need a flat? Do you still use the light pollution and background calibration tools? Probably going to start next clear stretch of weather we have.

Posted by: gdwats@comcast.net

 So I just sent my camera in for a hydrogen Alpha modification. I also have a 7mm baader hydrogen Alpha filter. It is my plan to take RGB images with the camera as modified followed by images taken from home using the 7nm hydrogen Alpha filter before the camera to pass only hydrogen Alpha and ignore all the street lights, and then to add these hydrogen Alpha filter frames as luminance. Does this make any sense? And would I do this in app or what I use Photoshop to blend the two Integrations?

Hi Greg,

Process the H-alpha exposures with the H-alpha debayer algorithm to immediately have the monochrome H-alpha to work with 😉 without loss of resolution.

Yes, it depends a bit on the object, but you could use the H-alpha layer as Luminance. Allthough in my experience, HaRGB composites where you blend Ha with the Red channel (and possibly other channels) works better than using it only for luminance. Bu then again, it's very data and object dependent, so you really need to experiment I think.

Just make sure that you have the integrations registered to each other, then you can combine the layers in the RGB combine tool to make a LRGB or HaRGB for instance (or in any other application if you want).

Cheers

Mabula

Posted by: gdwats@comcast.net

Also, when processing the hydrogen Alpha Subs do I not need a flat? Do you still use the light pollution and background calibration tools? Probably going to start next clear stretch of weather we have.

Yes, flat calibration is still needed to correct for dust and vignetting if present (usually is)

Yes, h-alpha data can be easily corrected with the LP tool:

H-alpha Data shot with a Nikon D600 mono (so bayer filters removed in this case) by Yves van den Broek

Background calibration is only applicable on multi-channel (so RGB)  data. So you can apply it on the composite that you make with the RGB combine tool 😉

Mabula

Thanks much. I would definitely prefer to add Ha to the red Chanel. Just need to learn how. Do I do an rgb stack first, separate into 3 channels, take the red channel and somehow add the HaRED channel to it in PS, then recombine the RGB channels or something? 

Posted by: gdwats@comcast.net

Thanks much. I would definitely prefer to add Ha to the red Chanel. Just need to learn how. Do I do an rgb stack first, separate into 3 channels, take the red channel and somehow add the HaRED channel to it in PS, then recombine the RGB channels or something? 

@gregwrca,

You can do this using the RGB combine tool, PS is not needed at all to make a composite. Major downside of doing it in PS is the fact that you need to stretch the data big time to use in PS which leaves you with less room to play with. In my honest opinion, it's much better to make any compositie while keeping the data linear.

In the RGB combine tool, just assign Red data to Red, Green data to Green, Blue data to blue, Ha data to Red and. Apply both Red and HA data with 100% ( so they actually contribute 50%) and increase the Ha-multiplier to 2-5 to get a nice Red + HA mix in the Red channel of the composite.

Kind regards,

Mabula

Thanks much. Was able to get 3 subs of 20min each on ic434:

Probably out of luck on getting RGB this year. Had some guiding issues as this sunk  into the trees to the West. Focuser on order.

When combining HaRGB, can I first somehow load the Ha image and RGB image and register them with each other so I can match up stars in the combine area?

Hey it worked! Not great material, bad and misaligned images but success. Thanks Mabula. Now just need some good data to work with this spring.

Posted by: gdwats@comcast.net

Thanks much. Was able to get 3 subs of 20min each on ic434:

Probably out of luck on getting RGB this year. Had some guiding issues as this sunk  into the trees to the West. Focuser on order.

Looks great 😉

Posted by: gdwats@comcast.net

When combining HaRGB, can I first somehow load the Ha image and RGB image and register them with each other so I can match up stars in the combine area?

Hi @gregwrca,

You need to have the channels aligned before you load them into the RGB combine tool.

Simplest way is to register and save them 😉 after having created the channels separately.

Mabula

Got it. I did register the 2 stacks
 together, then loaded the 2 registered
 image frames into rgb combine.
 Seems to have worked same?

Posted by: gdwats@comcast.net

Hey it worked! Not great material, bad and misaligned images but success. Thanks Mabula. Now just need some good data to work with this spring.

Making an HaRGB composite takes some practice. You need to experiment with the multipliers for the R and Ha channels and their % assignment to the red channel in the composite. Be aware that broadband Red has much more signal then the Ha narrowband data. This usually means that the multiplier of Ha needs to be much higher than the Red multiplier 😉 

It can also make a difference if you first register and normalize the channels before loading into the RGB combine tool. Normalization will help you to get a better initial composite. It makes the data of the separate channels more comparable.

Posted by: gdwats@comcast.net

Got it. I did register the 2 stacks together, then loaded the 2 registered image frames into rgb combine. Seems to have worked same?

Indeed !

Thanks again. Learning a lot here!

Above I used 2.5x on ha.