Gene Johnson wrote: > > Did we ever talk about using LED's for an enlarger? They have some pretty > bright ones now. Maybe a real dense array of say white,blue,green yellow > red. Maybe some could be turned off to change contrast? Just wondering out > loud. > > Gene > ----- Original Message ----- > From: "Uptown Gallery" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Thursday, September 19, 2002 10:01 PM > Subject: [Cameramakers] fluorescent lamps for b/w LF cold head enlarger > > > Hello: > > > > I am curious if anyone has ever used 'tri-phosphor' lamps for enlarging. > > > > I'm interested in an 8x10 enlarger for b/w only, on a budget. > > > > I started looking into low pressure pulsed xenon - lotta heat, and nearly > > obsolete, $100 for 750W lamp, $3000 for new commercial ballast/power > supply, > > and it's not a friendly prospect - 52 V at about 18 amps plus 10000 volt > > spike to ionize gas...so, I think I'll look into other approaches. > > > > Ansel Adams used massive array of logo-less incandescent lamps - heat > again. > > > > I'm pondering either full spectrum fluorescent (linear tubes only as far > as > > I know), or tri-phosphor complact fluorescent (3 spectral peaks spread out > > over visible spectrum depending on color temperature, 2700K, 3500 K, 4100K > > and 6500K available (CRI 82, but that may not be relevant to film). I got > > spectral plot of the 6500K one today because I was unfamiliar with that > one, > > and the spikey spectrum of the tri-phoshor type does make me > nervous...hence > > my request for others' fluorescent experience. > > > > What I'm considering is using seveal GE Biax (folded tube) 18 or 27W lamps > > for an 8 x 10 or 11x 14 head, each driven with a high frequency electronic > > ballast. Driving the lamps above 15kHz eliminates the 120 Hz (100 for 50 > Hz > > countries) flicker and produces about 15% more lumens than line frequency. > I > > have access to a manufacturer of small electronic ballasts (I used to work > > there). I am considering running them from a DC supply with individual > > regulators so the light output could be adjusted for each lamp. > > > > My main worry is the strong spectral peaks in this type of lamp. The > intent > > of this lamp design is that the brain is supposed to 'fill in the spectral > > gap', and THINK they are full spectrum lamps. > > > > Thanks in advance for responses. > > > > Murray > > > > _______________________________________________ > > Cameramakers mailing list > > [EMAIL PROTECTED] > > http://rmp.opusis.com/mailman/listinfo/cameramakers > > > > _______________________________________________ > Cameramakers mailing list > [EMAIL PROTECTED] > http://rmp.opusis.com/mailman/listinfo/cameramakers
Try this site: http://www.huws.pwp.blueyonder.co.uk/leden.htm and do a search on Lumileds. Regards, Marv _______________________________________________ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
