would lum channel add anything to M81 and M82

[iwols]

Well just imaged the above with 5 min subs but when looking through my images all the lum channels were well over exposed so just used R,G,B channels,just wondered if i re took the lum channels would it add anything to my final image,an thoughts  thanks

[Clarkey]

1 hour ago, iwols said:

Well just imaged the above with 5 min subs but when looking through my images all the lum channels were well over exposed so just used R,G,B channels,just wondered if i re took the lum channels would it add anything to my final image,an thoughts  thanks

I theory the luminance channel carries most of the image detail, so it should improve the image. However, in reality, by doing RGB only you are effectively producing something more akin to a OSC image. How much difference, particularly on bright targets like these, is another question. I think for very dim fuzzies the difference is likely to be more marked. As a rule my total luminance time is normally about the same as the RGB total time - so three times the length of each colour channel.

Edited April 28, 2023 by Clarkey

[symmetal]

The main contribution of the luminance is in improving the S/N of your image as it will gather signal around three times quicker than the RG or B. Hence them being overexposed if you used the same exposure time. If the background noise in your processed image is more noisy than you would like then adding some luminance will certainly help.

Depending on how well colour corrected your scope is, the luminance may actually be softer than the colour channel images as it can't separately focus for the specific colour bands when using luminance and must use  an 'average' focus position which best manages the full spectrum.

Alan

[ollypenrice]

What makes you say the L channel is over exposed? How have you come to this conclusion? Maybe you could link to a crop around one of the galaxies in the linear L data. Don't link to the whole image, the files are too big.

Olly

[iwols]

On 02/05/2023 at 18:52, ollypenrice said:

What makes you say the L channel is over exposed? How have you come to this conclusion? Maybe you could link to a crop around one of the galaxies in the linear L data. Don't link to the whole image, the files are too big.

Olly

thanks Olly unfortunately I've deleted the lum files but they were 2 white blobs strange really because I've never seen overexposure like it, not had chance since to recapture the lums Cheers