RE: UV light box construction
I built a light box last year for 12x20 which has been working fine. I
(Bcouldn't find any explanation of why the distance between the tubes should
(Bbe X and why the distance to the neg should Y so I set up a spreadsheet to
(Bcalculate the light level at various points across the film plane in order
(Bto find X and Y such that the variation in light level was insignificant. I
(Bended up with x=6cm and y=18cm which gives a theoretical 13% difference in
(Blight intensity centre to edge.
(BOf course the calculations are based on assumptions which are not correct -
(Bsuch as infinitely long tubes and zero reflectance from the sides. I think
(Bthe results of the calculations err on the conservative side and you could
(Bprobably increase X and reduce Y by some considerable amount before any
(Bvariation became 'material'.
(BI'd be happy to send the spreadsheet (Excel) should you wish to see it - and
(Banyone else on the list.
(BPractical advice - paint the inside white. Also I built my box upside down I
(Bthink - the box sits face up with the tubes near the floor and the printing
(Bframe goes on neg facing down. I don't think that has any material impact on
(BUK mobile ($B1Q9q$N7HBSEEOC(B): +44(0) 7770 787069
(BJapan mobile ($BF|K\$N7HBSEEOC(B): +81(0) 90 6440 7037
(BJapan land line / fax ($BF|K\$NEEOC$H%U%!%/%9(B): +81(0) 166 92 5855
(BFrom: Ken Sinclair [mailto:firstname.lastname@example.org]
(BSent: 22 February 2009 03:15
(BSubject: UV light box construction
(BI am now in possession of a sheet of baltic birch, 12 BL tubes,
(Bthe correct number of 'tombstones' and am almost at what one might call
(Bthe 'final, too-late-to-change design' stage.
(BI plan on having the lamps on one 'surface' of the birch 'plate' and
(Bthe ballasts on
(Bthe upper. I have planned to have this "rack" sitting on a 1 inch
(Bthe interior of the box to facilitate easy access when (and if) any
(Bof the parts need
(BBefore I commit the sheet of plywood to the table saw, I have to
(Bbelieve that some
(Busers may have found there to be an optimum distance between the
(Bwith the distance from the lamps to the top of the print frame.
(BPractical advice would be very much appreciated.
(BQuando omni flunkus moritati (Red Green's Possum Lodge)