The need for collumination depends upon the spaces you are trying to maintain. If you are shooting for less than 5 or 6 mils it's important. If your exposure time is longer that 1 minute (I didn't like to see it longer than 30 seconds) don't worry about collumination, get more lamps. You can overcome poor columination with intensity. The old Scanex's had crappy columination, but the effective exposure time was around 5 seconds and they worked pretty well.
----- Original Message -----
For home use, collimated light isn't really necessary, as most of us can't create high-resolution artwork that can make use of it. In fact, none of the low-cost UV exposure boxes that one can buy use it, they just have two or four tubes quite close to the PCB/artwork. I get quite good results with a couple of tubes about 15 cm from the PCB. Exposure is quite long at 13 minutes, I keep meaning to add another two tubes.
[Non-text portions of this message have been removed]