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HaRGB with diffraction spikes


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Hi all,

I'm shooting with a Newtonian so diffraction spikes are naturally a part of things.

However, in Ha I'm seeing far less in the way of spikes, even with a threefold exposure time over my L frames. Consequently combining HaRGB using PI's LRGBCombination to use Ha as L gives odd results:

RGB_DBE_clone_hargb.thumb.jpg.bb79940fa447e18b4e907ce82523c7d2.jpg

The Ha on its own (after curves+some more post, but you get the idea):

integration_ha_DBE_ABE.thumb.jpg.ac0f21b4a66938b2b2fe12e5ff984413.jpg

L, similarly processed:

integration_lum_DBE_deconv.thumb.jpg.084db9a2c4357edb45ae7536395f260b.jpg

And the RGB without either mixed in:

RGB_DBE_clone.thumb.jpg.2c879b9a1dbdd6206a3e1ec400e64c3c.jpg

Any ideas on how I might go about successfully creating a HaRGB image from this data?

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Hi..  in Pixinsight there’s a script called NBRGB (I think) that adds the Ha or other NB data..  you need to play around with the settings though and it’s s bit fiddly.  I have found though that it’s much easier If you have photoshop (or similar software) as then you can split the channels paste the Ha over the red channel and use blend mode lighten, you can also put an adjustment layer (levels or curves) on just the pasted Ha and adjust the result to taste.  Then recombine as RGB. Whichever way you go I think you might need to stretch your Ha a bit more before combining to make it contribute effectively.  Using Ha as lum generally makes the stars odd and any  red go pink.

HTH

 Dave

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22 hours ago, tooth_dr said:

Sorry I can’t help but that’s lovely data.  Will be interested in how this is done also. 

It's only a small amount - LRGB was about 4.5h, Ha 45 minutes - but a fairly fast/large aperture (200mm f/5).

13 hours ago, Laurin Dave said:

Hi..  in Pixinsight there’s a script called NBRGB (I think) that adds the Ha or other NB data..  you need to play around with the settings though and it’s s bit fiddly.  I have found though that it’s much easier If you have photoshop (or similar software) as then you can split the channels paste the Ha over the red channel and use blend mode lighten, you can also put an adjustment layer (levels or curves) on just the pasted Ha and adjust the result to taste.  Then recombine as RGB. Whichever way you go I think you might need to stretch your Ha a bit more before combining to make it contribute effectively.  Using Ha as lum generally makes the stars odd and any  red go pink.

NBRGB I tried but was unhappy with the results - until on revisiting it today I turned off the STF I had applied and realised the blueish tint was just a result of that. NBRGB with Ha for R gives this quite pleasing result:

NBRGBCombination.thumb.jpg.9b2d6376a912c03063d210c9944c2429.jpg

There's quite a lot of Ha in the background and this works really well I think. I'm not sure what magic is going on under the hood, but it's working.

 

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On 28/08/2019 at 09:03, Laurin Dave said:

split the channels paste the Ha over the red channel and use blend mode lighten, you can also put an adjustment layer (levels or curves) on just the pasted Ha and adjust the result to taste.  Then recombine as RGB.

 Dave

Thats how I do it. 

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