At 12:19 PM 2/23/2003 -0500, you wrote: > I've been thinking of how to enlarge 5x7 and 8x10 without buying an 8x10 >enlarger. > > It would seem a plywood box with a light source at one end and lens at the >other would be all that's needed. I spent some time with googles usenet >archives and saw people mention everything from 1100watt monster light >sources to 150watt work lights. Anybody know if a halogen work light would >actually work? The price is right. They generate alot of heat but I'm >guessing almost anything bright enough does. Some sort of diffuser between >the light and the negative holder would seem the easy way. Avoiding >condensors. A couple of fans to handle the heat? One pulling in room air the >other venting out hot air. Could I leave the top open? It would seem with the >lamp pointing down the plywood box not much light is getting out the back. It >would make cooling easier. > > > xxxxxxxxxxxxx >xxxxxxxxxxxxxxxxxxxxx >x x >x x >x x >x xxxxxx >x x x >x x x >x xxxxxx >x x >x x >x x >xxxxxxxxxxxxxxxxxxx x > xxxxxxxxxxxxx > > > Pardon the ascii art. Thats the basic shape. A negative holder in the middle. >A filter holder above it. Mounted on a table. With the easel mounted on a >wall. You'd move the enlarger forward/back to change print size. Or I guess I >could attach the easel to the table some how and make the easel moveable. > > Now the math part. Lets say I'd like to make a 24x30 from an 8x10. Is that a >3x magnifaciton or is it 1/3? > > The formula I have for figuring out bellows extension is > >bellows_extension = (1 + magnifaction) * focal_length > > But that's for the camera. An enlarger goes the other way. I'd like to use my >240mm process lens. It covers 5x7 at infinity but I'm hoping it'll cover >8x10 in this application. If not it's either the 210mm or the 360mm which >both cover 8x10. > >Thanks >Nick > >
Nick, Regarding the lamp - bounce the quartz shop lights ninety degrees off a flat white reflector. Mount a cooling fan off the enlarger with a foil clothes dryer flex duct. Use black foam core for box parts and 3/4 ply for structure. Mount everything on the wall if possible. See my pan enlarger on my web pages. Figure the lens coverage as the diagonal of longest sides. AZ Build a Lookaround! The Lookaround Book. http://www.panoramacamera.us _______________________________________________ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
