Led light for contact printing

[Cletus]

I do my Lodima contact printing under a shelf that has a fixture with three of those little 12v halogen lamps in it. I don't think the lamps are more than about 25W each and the fixture is located about 24" above my CP frame. I get a great print with a dense negative on Grade 2 Lodima in about 1.5 - 2 minutes.

I don't know if this is an unusually long printing time since I've never used anything other than this arrangement, but it works great for me and doesn't leave hotspots or evidence of uneven exposure the way I originally thought it might. I "accidentally" discovered this light source, which really amounts to my darkroom desk lamp, while trying to figure out how and where I was going to mount a light for contact printing on Lodima!

[Brian Ellis]

I used a normal indoor flood light in a reflector for years and it worked fine for contact printing. I don't offhand see why a LED light wouldn't work fine too, as long as it's powerful enough. The color of the light source doesn't affect the look of a contact print, it only affects the exposure time.

[cardiomac]

Cant wait to hear what you find out

Lodima seems to require UV or near UV light. It is very insensitive to most visible light, much like Kodak AZO. Completely different than Fomalux.

[Michael A. Smith]

Cemil is doing testing now with Lodima paper. He has been in touch with us and the results are looking promising.

We are having a more contrasty Lodima paper made. If interested, let us know.

Michael A. Smith

[wiggywag]

I do my Lodima contact printing under a shelf that has a fixture with three of those little 12v halogen lamps in it. I don't think the lamps are more than about 25W each and the fixture is located about 24" above my CP frame. I get a great print with a dense negative on Grade 2 Lodima in about 1.5 - 2 minutes.

I don't know if this is an unusually long printing time since I've never used anything other than this arrangement, but it works great for me and doesn't leave hotspots or evidence of uneven exposure the way I originally thought it might. I "accidentally" discovered this light source, which really amounts to my darkroom desk lamp, while trying to figure out how and where I was going to mount a light for contact printing on Lodima!

Thats a long exposure. With a 150w frosted bulb raised over the negative, so you get even light, your exposure time should be around 20 seconds.

[wiggywag]

Cemil is doing testing now with Lodima paper. He has been in touch with us and the results are looking promising.

We are having a more contrasty Lodima paper made. If interested, let us know.

Michael A. Smith

Can't wait for that paper!

Stig

[BlakeChapman]

Since Lodima and Azo paper is slow it needs a bright light. I been thinking of using a Led light that would be up to the task and found this


Any in this forum that have tried using a light similar for contact printing? What is your experience and advise?

Thanks

If you want to make one time investment and save energy you need to go with led lights otherwise bulb is fine for you

[BlakeChapman]

If you want to make one time investment and save energy you need to go with led lights otherwise bulb is fine for you

So which lights have you got?

[gleaf]

Technical sideways, as you said you said the subject was non threatening.
Cree and others produce high power LED's in many wavelengths. Edmund scientific and others sell optical quality opal glass which is a seriously grand diffuser. Three pole adjustable regulators can be wired as constant current sources and the sense resistor adjusted for light desired. Add a re-purposed power supply from and old PC. Many well wishes on your voyage in the technical toy box of life.

[Mark_S]

One thing to be careful about with LED lights is that LED puts out a single wavelength. To get a 'white' light, they take a blue LED, and then put a thin layer of a yellow phosphor over it - the blue light from the LED excites the yellow phosphor, which emits yellow - by adjusting the thickness of the phosphor you adjust the ratio of blue to yellow light until you get the blend that fools a human eye into thinking that it is white light, but your paper may not be so easily fooled...