Judy,
In response to your questions.
>Excuse me, please. What is a "drop in unit"?
A "drop in unit" in my terminology is a self-contained fixture in which one
can place one or two tubes. Ballast is included.
>
>> Unfortuantley, spacing is much greater than possible with single bulb
>> fixtures, which means that the unit must be used farther from the printing
>How far apart is "much greater" (approximately)? The 4-bulb units I've
>seen were all four feet long, but the bulbs were very close together.
Now excuse me, Judy, but what do you mean by "very close together"?
In my units, spacing between the tubes on the drop in units was about 3/4".
With bi-pole holders spacing can be less than 1/8".
>Sandy, have you tested the more widely-spaced bulbs (assuming still in the
>range of 2 inches or so) or are you just assuming they would be uneven at
>close distances? Someone told me he'd actually put the paper right on the
>bulbs and it was still even, tho maybe those were closer bulbs.
This would be an interesting test. For sure there would be uneveness but
what would be a standard for measuring it?
>
>I'll add that my exposure times for gum and cyanotype were so short at 1
>1/2 inches above tightly ranked single and double fixtures (although
>exposures were even) that I had to move paper stage higher.
>
Yes, sometimes longer exposures are easier to adjust to one's working
conditions.
Sandy