Re: update: screw-in BLB light-box

The issue of reflectors diffusing the light and resulting in loss of
sharpness was discussed at some length on this list some years ago.
I did not engage in that discussion (at least so far as I recall) at
the time, but subsequently I tested the premise myself and did not
observe any loss of sharpness at all when comparing tests *with
reflectors* and *without *reflectors.*

Just for the record, my own tests were done with a vacuum frame, as
opposed to a contact printing frame.

Sandy

>On Mon, 1 Aug 2005, jude.taylor@comcast.net wrote:
>
>>I did not use any reflectors, but that is a possibility that might
>>help. The top of the box INSIDE above the bulbs is all white and
>>should, as far as I can figure, reflect rather than absorb the UV.
>>There are, however, several inches of space from the tip of the
>>coil to the base of the ceramic sockets (top of box), and the
>>sides of the box were not painted white or lined with reflective
>>material.
>>
>>Hummmh! I wonder if silver / white "tea chest" paper lining would work?
>
>Judy, I have no idea if my experience with reflectors would apply to
>your experience with reflectors, but --FWIW -- I found that all the
>ones I tried (with tube flourescents) diffused the light either some
>or a lot, hence costing sharpness, some or a lot. Crumpled aluminum
>foil on the base was the worst, but even just plain white cost
>sharpness. I don't know why exactly. But I don't need to know why. I
>observed it -- (easiest to judge how much with a 21-step of course).
>
>"Tea chest" paper might be medium bad -- not likely to lie
>*perfectly* flat, also with some pattern or mini-grooves of
>reflection, but not as bad as crumpled foil.
>
>That, BTW, may not happen in your setup as much as it did in mine if
>you've got serious-level vacuum frame -- but that's only a guess. It
>could be irrespective of print sandwiching techniques, but in any
>event needs to be watched for.
>
>Judy
Received on Fri Aug 5 12:15:41 2005