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H Alpha filter - no idea what to do

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#1 PhilNight

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Posted 12 February 2024 - 07:56 PM

Hi, I was give a clip in H Alpha filter for my dslr as a present. But I've no idea how to process images from it. All the images are red. Everything. Any guides on how to process with those and ordinary dslr images combined?
Thanks

#2 hyiger

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Posted 12 February 2024 - 08:18 PM

The spectral line of Hydrogen Alpha is 656.28nm which is a deep red. So... everything is going to be red. Also, unless your camera is modified it won't be that sensitive to Ha.

 

You can take a set of RGB images (say 30 or so) and H-a images (again 30 or so) then stack them together which will give you a stacked RGB and stacked Ha. Split out the RGB into separate channels then combine with H-a by adding it to the red channel. 


Edited by hyiger, 12 February 2024 - 08:18 PM.

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#3 bbasiaga

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Posted 12 February 2024 - 09:10 PM

https://youtu.be/UiE...UeQFnEs4cqR4r_y

I actually just saw a video on how to do this in Siril today.
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#4 idclimber

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Posted 12 February 2024 - 09:11 PM

Don't even try, convert it to black and white like this. 

 

get.jpg?insecure

 

 

Otherwise you would need to combine the Ha data with some data without the filter. 


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#5 Jlex

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Posted 12 February 2024 - 10:15 PM

Hi, I was give a clip in H Alpha filter for my dslr as a present. But I've no idea how to process images from it. All the images are red. Everything. Any guides on how to process with those and ordinary dslr images combined?
Thanks

How long were your exposures (subs)?  


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#6 ntph

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Posted 12 February 2024 - 10:33 PM

But you can do it--and why not!! HaRGB is what I think hyiger is getting at, but here is a video from Dylan O'Donnell that simply shows some of the ways of combining data. Of course, there are many ways to do this, but Dylan gives a good overview in this video  (not the actual processing part--for that I recommend perusing Cuiv the Lazy Geek's extensive bideo collection or using any of the "standard" texts--Miller, Bracken, etc.). Certainly Dave is right--you can get very nice monochrome ie black and white images just using Ha data. But you are not limited to just that. No different than combining data from a dual-band filter used on a OSC camera with broadband data--folks do it all the time. 


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#7 Robert7980

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Posted 12 February 2024 - 10:40 PM

+1 This is what I’d do, once it’s grey scale you can do whatever you want with it from there… 

 

Don't even try, convert it to black and white like this. 

 

get.jpg?insecure

 

 

Otherwise you would need to combine the Ha data with some data without the filter. 


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#8 bobzeq25

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Posted 12 February 2024 - 11:03 PM

Note that the H alpha filter is NOT designed for use with a color camera.  It's designed for a mono camera.

 

It will work some, but with a color camera you only using some of the pixels.  With a mono camera you're using all of them.  That's better.  I'll bet the image in #4 was taken with a mono camera.  @idclimber - yes?

 

There are similar filters that ARE designed for color cameras.  They're called duoband filters.  A common one, made in clip on style for a DSLR, is the LEnhance.  They use all the pixels.

 

They also produce a color image.  Win-win.  Much better.

 

Neither of these filters works all that well with a stock DSLR.  A stock DSLR blocks most of the H alpha light.  To fix THAT, you can modify the camera to pass H alpha light.  Like this (one alternative, and a good one.)

 

https://www.lifepixe...mera-conversion

 

Bottom line.  By all means have fun with your filter.  But.  It can't give you a color picture, just a red one (or black and white).  It won't work as well as an LEnhance.  If your DSLR has not been modified, it won't work well at all.

 

Bottom line.  Don't expect too much.  Don't expect the same quality pictures as others you've seen, especially if your DSLR is not modified..  That filter is not going to get you great results, especially if your DSLR has not been modified. There is no magic fix, although somewhaat longer subexposures and MANY more of them will help.  The problem is not your skill, it's just an inevitable result of using that filter with that camera. 


Edited by bobzeq25, 12 February 2024 - 11:08 PM.

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#9 PhilNight

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Posted 13 February 2024 - 06:31 AM

The spectral line of Hydrogen Alpha is 656.28nm which is a deep red. So... everything is going to be red. Also, unless your camera is modified it won't be that sensitive to Ha.

 

You can take a set of RGB images (say 30 or so) and H-a images (again 30 or so) then stack them together which will give you a stacked RGB and stacked Ha. Split out the RGB into separate channels then combine with H-a by adding it to the red channel. 

Thanks everyone for helping with this.

I should have added more info, the dslr isnt modified, 

I kinda knew the filter was more of a red channel or B&W than anything like images as having separate filters.

But again I hadnt a notion of what to do, so this has given me a lot more info than I had yesterday and cant wait to give it a try.................eventually........when the clouds go away which have been around for weeks.

 

Thanks again.


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#10 PhilNight

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Posted 13 February 2024 - 06:38 AM

https://youtu.be/UiE...UeQFnEs4cqR4r_y

I actually just saw a video on how to do this in Siril today.

I need to learn Siril, it looks so cool to use. Thanks for this.



#11 PhilNight

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Posted 13 February 2024 - 06:40 AM

But you can do it--and why not!! HaRGB is what I think hyiger is getting at, but here is a video from Dylan O'Donnell that simply shows some of the ways of combining data. Of course, there are many ways to do this, but Dylan gives a good overview in this video  (not the actual processing part--for that I recommend perusing Cuiv the Lazy Geek's extensive bideo collection or using any of the "standard" texts--Miller, Bracken, etc.). Certainly Dave is right--you can get very nice monochrome ie black and white images just using Ha data. But you are not limited to just that. No different than combining data from a dual-band filter used on a OSC camera with broadband data--folks do it all the time. 

I think O'Donnells channel is great. Cheers




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