Quote:
Originally Posted by Tom Davis
Excellent detail and FOV!
Tom
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Thanks very much Tom!
Quote:
Originally Posted by strongmanmike
What are these extinction factors and ratios you speak of.?
Mike
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Hey Mike...
Ratios are my G2V star weights that match my system.
I'm sure we've discussed this before???
Ok I take an even amount and exposed subs in all channels but apply them with different intensities.
For my system- R=1.215 G=1 B=1.282. (these figures were derived from taking short exposures of a G2V analogue star with my setup. You write down their separate intensities and divide first the red into green... this is your red ratio, divide the blue into the green... this is your blue ratio and we call the green 1.) You still have to add a multiplier factor to what ever altitude you were shooting the star at, because of colour extinction, but once this is done, these ratios/ weights are your base...
Ok, so these ratios are if I we were pointing our scope up at 90* at the zenith... no interference, shortest distance of atmosphere to go through.
The further you go down from zenith, the less transmission certain wave lengths have, more so with blue light.... because there will be more interference and more atmosphere to go through.
I use a chart that tells me the multiplier factors I need to use in conjunction with my pre- determined rgb ratio/ weights.
Ex. if the object was at say 65*.. my chart tells me I need to multiply my R (1.215)x 1.011, G(1) x 1.017 & B(1.282) x 1.026.
So now my corrected weights will be
R=1.228, G= 1.017 and B=1.315... this is what I plug in maxim when I do a rgb combine.
This of course can fail if conditions change in the night. But at the very least it gives us a mathmatical pedestal to work.
A few guys who are no slouches developed this method back in -1998 when ccd detectors were coming of age..... Chuck Shaw, Al Kelly, Ed Grafton and Richard Berry.... plenty on the net about them. I remember reading the article in Sky and Telescope.
You can use Richard Berry's AIP4WIN which has a colour calculator tool in it as well.
I know some compare their images to others on the net and adjust accordingly, but why do this when we have a mathmatical approach rather than guess work. Many imagers use this method.
Yep, all artistic license though I know, and up to each and every individual on how they want to do things......
Quote:
Originally Posted by Ric
Lovely image rich, that's a beauty.
So clear and detailed.
Cheers
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Thanks very much Ric !
Cheers all, hope you're able to get out while the moon's gone!
Rich