U of S | Mailing List Archive | alt-photo-process-l | Re: Some Lights It Hot, Some Lights It Cold

Re: Some Lights It Hot, Some Lights It Cold

This is called a light integrator. It calculates how much light has fallen on a specific area and measures the amount in units, as water meters measure volume.

Light integrators are necessary with the HID (high density discharge) lamps used in plate-burners because the intensity of the light is not 100% until the unit has been on for a minute or so. However, radiation is 100% with BL fluorescent tubes within 5-10 seconds of turning them on and does not change much even with long exposures, unless the tubes and ballast get hot.

Do you have a fan installed on your unit? If not, I would install a fan before worrying about an integrator.

Sandy King

At 8:22 AM -0600 3/8/07, Michael Koch-Schulte wrote:
Forgive me the headline, I'm atoning for a life of typos...
Seriously though, I have a real question... I use a bank of UV BL
fluorescents to print my work (a la Eepjon). I've been weeding out the
errors, big and small, in my process lately. I find that when the are hot,
used within the last half hour, they are anywhere from one-third to
two-thirds a stop faster than when the lights are "cold". The difference
makes printing to highlight and calibration (using the term loosely) a real
pain. I know on commercial units there is a sensor which calculates how many
"units" of UV has been emitted so the operator can compensate. Has anyone
built a similar switch for the smaller light boxes?