From: John Campbell (tojohn@texas.net)
Date: 11/12/02-11:10:59 PM Z
Sandy,
Which integrator (manufacturer/brand/model number) is in your configuration?
TIA,
John
www.photogecko.com
----- Original Message -----
From: "Sandy King" <sanking@clemson.edu>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Tuesday, November 12, 2002 10:47 PM
Subject: Re: Consistency Is No Hobgoblin
>
> Jeff wrote:
>
>
> I am not saying that the variations in temperature and humidity are
> not an issue. However, I will say with absolute certainty that 2-3
> minute warm up time is not sufficient for most commercial metal
> halide lamps to reach full output. With an integrator you calibrate
> the unit to reach a certain output, which in my case I have set to
> 100 when the the unit of operation is approximately one second. At
> 2-3 minutes my unit, as measured by the integrator, has only reached
> a reading of 20-30 units, that is, less than 25% of full output.
> Obviously if your exposures are in the 10 minute range and you begin
> them at 2-3 minutes of turning on the light, you should be seeing
> significant variations in printing density, irrespective of any other
> factors.
>
> Sandy King
>
>
>
>
>
>
>
> >Clay & Sandy: Thanks for the suggestions. As you know, I have a
> >metal halide HID. I don't worry much about timing the exposure,
> >because they run 6-8 minutes typically and I don't see how the 2-3
> >second fudge in my crude timing system can make any difference. The
> >intensity of the lamp is another matter. When I got the thing last
> >spring, I followed leads to get an integrator, but pretty much
> >crapped out when the glass-virtuoso guy proved no help. On the
> >other hand, looks like I should be doing a longer warm-up. I've
> >been doing 4 minutes because the electrician said 2-3 minutes would
> >be plenty. As for the quiet time around the house, I can manage
> >that sometimes and I try to.... Say, are you guys saying that the
> >variations in temp and humidity I noted are probably not at issue?
> >-JB
> >
> >At 11:04 PM 11/12/2002 -0500, you wrote:
> >
> >>Clay wrote:
> >>
> >>>Jeff:
> >>>
> >>>What are you using for your light source? And how are you timing
> >>>it or measuring it. I find I get pretty consistent results with
> >>>the same materials and ambient conditions... But I'm using a Nuarc
> >>>most of the time.
> >>
> >>
> >>When using any UV light source without an integrator one is almost
> >>certain to observe some small differences in print density, even
> >>when all other things are held to absolute consistency. I find this
> >>to be true with both my bank of BL tubes and with the HID lamp when
> >>used without the integrator.
> >>
> >>If one must work without the integrator it is best to do so when
> >>the house is relatively quite and there are no large and sudden
> >>current drains. Also, for maximum consistency all light sources
> >>should be allowed to warm up for a few minutes before exposing. Two
> >>to three minutes is enough for fluorescent tubes, while HID mercury
> >>vapor and metal halide lamps need from 5-8 minutes to reach maximum
> >>output.
> >>
> >>Sandy King
> >>
> >>
> >>>
> >>>Clay
> >>>On Tuesday, November 12, 2002, at 08:58 PM, Jeff Buck wrote:
> >>>
> >>>>Actually, it's the tendency of a phenomenon to recur in the same
> >>>>form.... Anyway, after doing platinum/palladium for about
> >>>>fifteen months now, I find if very difficult to achieve. I
> >>>>arrive at a print that is satisfying. I want to repeat it. So,
> >>>>I use the same paper, the same chemicals (plain FO, pure
> >>>>palladium, PO w/ sodium dicromate mostly), the same exposure, and
> >>>>the same developer. As for ambient temperature and humidity, I
> >>>>can get pretty close to repeating, especially this time of year
> >>>>when I'm producing both artificially (by and large). Like the
> >>>>last couple days, I'm printing this negative, and the temp is
> >>>>between 65F and 70F, the humidity is in the range of 60% to 70%.
> >>>>In each instance, the paper has been laying out in the area of
> >>>>that temp and humidity for a few hours; it's a little "heavy" and
> >>>>tacky to the touch. I guess I made four prints in these
> >>>>conditions (I was double-coating Platine, if that makes any
> >>>>difference). There were notable differences in the overall
> >>>>darkness of the prints and in degree of contrast. Would you
> >>>>expect discernible differences working within these variations in
> >>>>temp and humidity? How do you measure the temperature of the FO
> >>>>and platinum or palladium? I'm squeamish, maybe for no reason,
> >>>>about putting a thermometer into a bottle of precious metal....
> >>
> >>
> >>--
>
>
> --
>
>
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