Saunders 4550XL light fall offgreenspun.com : LUSENET : Large format photography : One Thread
I have just been fussing around changing my standard routine for proofing contact of (4)4x5 negs on a sheet of 8x10 paper. As I was doing this I noticed that there seems to be light fall off. I am set up with the enlarger height and "focus" at the point where a 4x5 neg would be as if enlarged full frame to an 8x10 piece of paper. I measured it several ways (incident and spot) with my Sekonic L-508 and there is an even fall off of 1/2 EV from center to edge. I was kind of surprised. Now I don't know if this is typical or will even make much of a difference in real world printing. I hadn't noticed any problems with my prints but will go back and look. Despite this I would still love some comment on this from those more experienced than I with this finding. Thanks!
-- Scott Jones (email@example.com), January 21, 2002
I measured time ago in the same way than you with the same results. I have a lpl 7452 color head, 250watts, apo-rodagon 150mm. I think itīs normal. If needed, I expose a bit more this area...
-- jose angel (firstname.lastname@example.org), January 21, 2002.
You will find that light falloff is pretty routine with most enlargers, perhaps this is why most printers burn in the edges of their prints !
-- Jeffrey Scott (email@example.com), January 21, 2002.
i noticed the same thing. when i have to print a 24x20 print out of the 4x5 negative, i use a 120mm lens. the fall off is less since the head does not have travel as far up the column. this seems to work pretty well, but i use a 150mm lens for any enlargement that is less in size. regardless, i always burn the corners and edges of all my prints.
-- howard schwartz (firstname.lastname@example.org), January 21, 2002.
For contact printings I do not focus the enlarger at all and I make sure if I want contactprints on a 8x10 paper the enlarger is in a position for where he covers at least 10x12 and I also close the lens 1 f stop down. So I have only ilumination differences at about lesser then 1/10 f stop!
-- Armin Seeholzer (email@example.com), January 22, 2002.