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iwols

lrgb percentage

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hi guys i know it may vary but typically what percentage do you do the following lrgb images for dso ie do you do twice as many l as rgb if you know what i mean

thanks 

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I usually decide how long I can image for - lets say 6 hours.

I will use about half the time on Lum binned 1x1 and the other half split equally between RG and B binned 2x2

If the target starts low to horizon but is climbing I take the RGB first so my Lum is taken at the highest/clearest point.

If its a descending target I take Lum first then RGB.

Not saying its the best way but it works for me !

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That sounds a good strategy Dave, I must admit I tend to do a sequence of twice as much Luminance as RGB just repeating itself, but using the higher altitude for the Luminance does sound a good plan.

Carole 

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5 hours ago, Skipper Billy said:

I usually decide how long I can image for - lets say 6 hours.

I will use about half the time on Lum binned 1x1 and the other half split equally between RG and B binned 2x2

If the target starts low to horizon but is climbing I take the RGB first so my Lum is taken at the highest/clearest point.

If its a descending target I take Lum first then RGB.

Not saying its the best way but it works for me !

why RG and B binned 2x2 thanks

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I believe this is because your luminance layer contains the important detail of the object and RGB is just adding the colour information and doesn’t need to have all the detail of the luminance.

i too am just learning the right balance with a mono camera. 

One thing to remember, if you do take the rgb 2x2 then don’t forget to take 2x2 flats! 

Bryan 

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7 hours ago, iwols said:

why RG and B binned 2x2 thanks

The detail is all in the Lum layer - much less important in RGB so I go for speed in RGB and detail in Lum.

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Also be aware if you bin the RGB you'll need software capable of re-sizing the RGB to match the Luminance as it will be half the size. 

Carole 

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I spend an evening on a filter. Current project, trying to get 3 hours each RGB and as much Lum as possible. Some cameras have a different QE response also. Like my ASI1600 is more receptive to red and green and a little less blue, but not by much. So you could say you'd need a little bit extra blue to match the others. I just shoot equal RGB. An hour each at least.

 

Regarding Carole's point above, if you bin RGB and you have Pixinsight, a star alignment will auto align the binned and non binned files without fuss.

zwo_asi1600mm-pro_qe_graph.jpg

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I don't like binning colour because I tend to use little or no luminance on the final stars, certainly on targets with starfields on 'empty' background. So I want nice tight stars with good colour close into the core rather than too saturated.

On the main question of the L to colour ratio, you'll probably find processing easier if you shoot the same amount per filter. However, if the target has interesting faint signal to bring out then shooting more luminance will do exactly that. You can shoot vastly more luminance to find the faintest stuff but combining it with the colour becomes considerably more difficult. Very strong Lum needs to be added in small interations, the colour saturation increased, the noise reduced and the partial lum re-applied, this process repeated several times. The last application of Lum is done without noise reduction to restore detail.

If imaging at high resolution it is worth allowing the seeing to inform your decision of what to shoot and when. If the FWHM values are good, shoot lum. If not, shoot colour. At lower resolution this is less critical.

Olly

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