>Subj: Re: UV Light banks
>Date: 97-11-01 00:15:51 EST
>From: DKenn473
>To: richsul@roadrunner.com
>To: alt-photo-process-l@skyway.usask.ca
>Dick- we tried a test tonight using a metro-lux and it didn't prove out as
>above.
>one lux with light source 6 inches from probe surface was six seconds while
>one
>lux with light source 2 feet from probe was 15 seconds. The light source was
>16- 90 watt blubs with a total width of 25 inches and length of 3 feet.
> Working on the large prints we've been doing latelyI've noticed that our
>exposure times have increased greatly even though the "lux" eposures have
>remained the same. ie a 45 lux exposure with the exposure unit 2-3 inches
>from print is about 4 1/2 mins
>when the unit is 2 feet above print it is more like 15 mins. It amazing how
>when theory meet reality- reality usually wins out. Any thoughs on this?
>
>David Kennedy
>
David,
I don't remeber when I tested this but I never went out as far as two feet.Your test more or less confirms what I said. You 3x'd the distance and only fell off a little over one stop. Point source would have been 9 stops. The larger the bank, the less the fall of. Had you boxed it in with high white sides, the fall-off would probably been a whole lot les, minus only what the sides absorbed and didn't reflect back to the surface. BTW, for those building systems, white paint is more reflective than aluminum paint.
Cheers.
Dick
Think of a 100 foot x 100 foot bank. as you move away from it there would be very little fall off.
Maybe Bob Schramm can illucidate this further.
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