From: Sandy King (sanking@clemson.edu)
Date: 09/29/03-08:07:02 PM Z
Mark,
>
>
>So my FIRST QUESTION is this: Am I correct in assuming that an
>exposure of say 400 UNITS would not be the equivalent between
>machines?
I think that is probably the case, except for people like me who have
adjusted their light integrators so that one second equals one unit.
>
>My SECOND QUESTION is this: I heard somewhere, maybe at Starbucks,
>that you could adjust the UNITS to different values. I've looked
>all over the place to do this on this thing and I don't see any
>adjustment dial, screw, lever, button or anything. Should I give up
>looking?
All of the Olec light integrators that I have seen have provisions
for adjusting a unit to be whatever you want, but the literature that
describes making the adjustment indicates that it is common practice
in the platemaker trade to adjust the integrator so that one unit
equals one second, or more or less so. But you don't have to do that
so that in fact a unit can be much less than a second, or much more
than a second.
>
>My THIRD QUESTION is this: I thought my right hand looked a little
>pallid, so I got out my light meter and took readings at various
>points on a grid over the bed of the NUARC. I used the foot candle
>setting. I assume that I am not getting accurate UV readings with a
>standard light meter, but perhaps some indication of what might be
>going on. In doing so, I found variance over the bed from 900 to
>2200 foot candles. Has anyone ever looked at how even their NUARC
>exposes images? If so, is it good or bad? Is anyone noticing hot
>spots or cool spots on their prints? Or should I just figure it's
>close enough for Gum printing and forget it?
I have not found that an exposure meter gives an accurate indication
of actual UV light as it relates to printing density in stops. The
best way to test for uniformity of illumination is to expose five
sheets of sensitized material of a UV sensitive process to a Stouffer
step wedges. Make all five exposures at the same time, and for the
same amount of time. Put four of the sheet at the extreme corners of
the easel, and one in the exact middle. Develop and evaluate the
densities and this will immediately tell you how uniform your light
is.
Sandy
>
>Thanks for your kind responses in advance.
>
>By the way-I still am a victim of the AOL conspiracy to keep me
>uninformed, so I don't get every post that comes from the list.
>Should I not respond to someone's question on the list, send it
>again to me privately and I will be happy to respond. I fear I have
>missed at least half the posts on Indigo/Gum and my score card is
>probably no longer valid for lack of complete data.
>
>Mark Nelson
>(He Whose Right Hand Is Now More Tan Than His Left)
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