You really need a fan in the box. If you don't have one the bulbs will heat up during exposure and light output will fall dramatically, to less than 40-50% of output when the bulbs are kept cool with a fan. You can not see this with your eyes but if you have light integrator the fall-off in output is dramatic.
Originally Posted by Jeremy Moore
Regarding Bill's comment about the BL and SA tubes my testing has consistently shown that the BL tubes print slightly faster than the SAs. But many people agree with Bill's finding and as far as I can determine opinion appears to be about equally divided as to which bulb prints faster. However, there is a slight difference in contrast in the mid-tones between the two lights that results from more belly in the curve of BL prints. This information will be found in the appendix I did for the new edition of Dick Arentz' book on platinum printing which should be out in a few months.
However, if your intention is to print both Pd/Pd and one of the dichromate colloid processes there is no questio but that the BL tubes is overall much better.
Last edited by sanking; 06-20-2004 at 09:00 AM. Click to view previous post history.