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Old 10-08-2011, 08:35 PM
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Tandum (Robin)
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L to RGB Exposure Times.

I was shooting some flats earlier tonight and threw in some LRGB while I was at it. I notice that with the same light box setting, L needs 6 Secs exposure to reach 22,000 while Red needed 20 Secs and GB needed 15 Secs.

That's roughly a 4:1 ratio against an LED light box. I'm hoping to shoot off a few subs on a G2V star before I shut up shop to double check the numbers against a white source but does this mean I can knock back my Lum exposures to be a quarter of my colour exposures? Or extend do I extend my colour exposures?

What am I missing here?
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Old 10-08-2011, 08:44 PM
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kinetic (Steve)
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Robin,

I'd suggest it's maybe because the LCD/LED? backpanel light
is giving three spikes of light as in this pictured link.
http://ledmuseum.candlepower.us/eighth/soyomon.gif

(further narrowed by the filters too , maybe) .....
Compare that to a more continuous G2V spectrum and that could account
for the 4x exposure needed.

Steve
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Old 10-08-2011, 08:54 PM
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Tandum (Robin)
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Cheers Steve. I've got a G2V data base loaded in sky so it's a no brainer to snap a few shots off. I have already done the RGB filters but didn't think about Lum. In retrospect, I'd imagine it should be a 3:1 ratio as RGB is additive?

[edit]
Yes it's additive. I got 45K for L and 27K, 25K and 17.5K for RGB but only shot one 5sec sub on a G2V for each.

Last edited by Tandum; 10-08-2011 at 09:49 PM.
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