Led light for contact printing

[wiggywag]

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
http://www.amazon.com/JK-led-Die-cas...=24w+led+light

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

Thanks

[Jon Shiu]

I use a regular 60W bulb in reflector @ 30" with AZO and it works fine.

Jon

[Jac@stafford.net]

No. Those interior lights are focused. Not good and not strong enough.
A regular photo-flood bulb in a reflector hung far enough away from the contact frame is best.
I use (because I have so many) a 250 watt bulb on a timer

Jon Schui's suggestion is also very good for longer exposures.

[wiggywag]

A have also been thinking of using strong LED light together with a battery to have a very stable power output, which canbe useful for printing.

[Sevo]

A have also been thinking of using strong LED light together with a battery to have a very stable power output, which canbe useful for printing.

Well, work with exposure times notably below 1/50s might benefit from DC powering. But contact printing? You would not even see a difference if you exposed the contacts with flashes in ten-second intervals...

In general, LED lights are too weak. Or rather, too expensive by photometric unit - once you go past 8-12W (the illumination strength of a 75W incandescent household bulb), prices get unreasonable. High power LED sources equivalent to 500W halogen exist, but these do not only need special power sources and reflectors, but also are so expensive that they are only marketed as marking or signal lights for inaccessible places, where they pay for themselves over their long unattended life time. If you have a application that asks for less than 100W in household bulbs with no particular illumination characteristics, go for LED. Otherwise, it is a expensive choice, often with spectral or illumination issues you would not have with much cheaper lights...

[cardiomac]

A have also been thinking of using strong LED light together with a battery to have a very stable power output, which canbe useful for printing.

I have built a custom, high output, blue LED 4x5 lamp for enlarging on to Fomalux silver chloride paper. The exposure times needed were comparable to those typical of standard enlarging paper. The cost of the lamp was about $30 more than a standard, white light Model 2.

I'm not sure the same results will be seen with Lodima paper because I suspect the Lodima requires UV or near UV light. I will be doing some tests in the next few weeks and should know for sure soon.

Cemil
www.modernenlargerlamps.com

[Jim Jones]

Perhaps in the near future a mosaic of LEDs near the printing frame and controlled by a computer will permit the dodging and burning to be preset for finer control and repeatability.

[Kevin J. Kolosky]

Just a quick question about something I don't know about. You say this Lodima paper is so slow, and I would guess that is why people don't enlarge with it.

Question is this. If a person is a patient person, can you enlarge with it? Or ot put it another way, how long would the exposures be if you used an enlarger with it?

[Drew Wiley]

Chloride papers will indeed work for enlargement if you have an enlarger lens with a relatively large max aperture and good strong halogen source, typical of pro colorheads. This doesn't mean the tonality will come out exactly like that of a contact.

[wiggywag]

I have built a custom, high output, blue LED 4x5 lamp for enlarging on to Fomalux silver chloride paper. The exposure times needed were comparable to those typical of standard enlarging paper. The cost of the lamp was about $30 more than a standard, white light Model 2.

I'm not sure the same results will be seen with Lodima paper because I suspect the Lodima requires UV or near UV light. I will be doing some tests in the next few weeks and should know for sure soon.

Cemil
www.modernenlargerlamps.com

Cant wait to hear what you find out