From: Michael Mutmansky (psu4ever@ix.netcom.com)
Date: 02/11/00-04:39:41 PM Z
William,
I agree, and am planning on getting an Olec integrating timer, rather than a
metrolux. The Olec are made for UV exposure (for pre-press) so I would expect
them to be more suitable. They also can come with controls to turn on the
vacuum pump, etc. so they really do seem to be a good method. Also, they are
available used fairly inexpensively.
However, if you are not using an integrating timer, then you should be aware of
the output depreciation when a neg you printed last year is just not coming out
the same this year!
As I noted, these performance curves are general, but even so, after the first
1000 hours, the lamps may require an additional 1/2 stop of time added.
Considering the level of accuracy most photographers work at, this is not
terribly significant, and will fall into the overall noise level of variables
that are not controlled to high precision.
---Michael
William Laven wrote:
> >
> >As I originally stated, the output goes through it's most dramatic
> >changes at the very beginning, so I would recommend "seasoning" the
> >lamps for at least 100 hours before trying to establish any type of base
> >exposure times. In the chart from Philips, the curve is still quite
> >vertical out to about 300 hours, and then curves to a slight downward
> >straight line by 1000. When the lamps are young, you are going to have
> >problems getting a reliable base exposure time.
>
> This is exactly why the Metrolux timer or a light integrator is so good for
> exposure units. Why burn lamps for 100 hours when you could be printing
> then and still achieving predictable consistent exposures with a light
> integrator/Metrolux?
>
> Also, while the Philips graph indicates such a precipitous drop, I've not
> seen that with my printers (several of my own and several which I use in
> workshops). That is, my exposure times didn't have dramatic increases in
> response to the suggested decrease in lamp output.
>
> I wonder whether others' experience is similar or different.
>
> Curiously, a few days ago I was printing and the exposure times were
> consistently faster than they were a year or so ago when I last did a
> calibration on the Metrolux,suggesting that the lamps' output had
> increased! Go figure.
>
> ********************************************************************
> WILLIAM LAVEN PHOTOGRAPHY
>
> Tutorials in Platinum/Palladium printing and Zone System.
>
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>
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