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-casting-Downlight-Spotlights/dp/B00AR90NFG/ref=sr_1_41?s=lamps-light&ie=UTF8&qid=1365791453&sr=1-41&keywords=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 ;)

[Mark Sampson]

I'm not patient enough for 4-minute print exposures when enlarging on Azo (I tried it). As opposed to 20" on enlarging paper. Michael and Paula's Azo forum has a section about enlarging on Azo/Lodima, including someone who was making an LED head, but I haven't looked at that site in years, probably. I thought about rigging up a Dyna-Lite strobe head as the enlarger light source, but never got around to it.

[Drew Wiley]

A few commercial heads have been marketed for azo, and even for pt/pd. Overheating was a problem. The prints will blacken if your darkroom catches fire too!
A bit too much DMax. Actually, any true color mural head would punch azo in a matter of seconds. I once had one and the utility bill just for the cooling fan was more per month than my entire house... there were four exhaust hoses of pure silicone (worth about $700 apiece), and the fan itself drew more wattage than an industrial table saw. You get the idea. But it can be done via halogen enlarging. The LED option looks interesting but I'm a bit skeptical if it would make much difference. And
if you tried to obtain variable control of the amt of an entire bank of lights, you'd run into EMI hell. Simply switching a bunch of em on and off all at the same time
might work. Somebody will try and the learning curve will progress...

[Tin Can]

I like the concept.


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.

[Drew Wiley]

The idea of dodging/burning with a light bank is actually a poor idea. Ole Ansel tried that with toggle switches, and many people have since. It gives way less control than the simple dodge/burn card method, and introduces a major level of headaches. To computer-control complex LED lighting you have to go to sinewave control. Avail, yes.... expensive, yes,yes, yes.... subject to constant software upgrades and potential rapid hardware obsolescence too, yes! But if ya gotta try I, I do know how. But I'd wait a little longer, since LED is a lighting category rapidly evolving at the moment.

[Tin Can]

We can wait, tech advances are accelerating.

Somewhere I postulated the end of physical displays, why not just wire directly to optic nerve. After all the blind now see with hardwired imagers.





The idea of dodging/burning with a light bank is actually a poor idea. Ole Ansel tried that with toggle switches, and many people have since. It gives way less control than the simple dodge/burn card method, and introduces a major level of headaches. To computer-control complex LED lighting you have to go to sinewave control. Avail, yes.... expensive, yes,yes, yes.... subject to constant software upgrades and potential rapid hardware obsolescence too, yes! But if ya gotta try I, I do know how. But I'd wait a little longer, since LED is a lighting category rapidly evolving at the moment.

[Drew Wiley]

Think you're getting a little close to X-Files reruns. There are already too many geeks wandering around this neighborhood with bar codes on the back of their
necks!

[Tin Can]

Google Glass embedded. It is all coming, no fiction needed.

I bet the military is very close right now.


Think you're getting a little close to X-Files reruns. There are already too many geeks wandering around this neighborhood with bar codes on the back of their
necks!

[Brian C. Miller]

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.


The idea of dodging/burning with a light bank is actually a poor idea. Ole Ansel tried that with toggle switches, and many people have since. It gives way less control than the simple dodge/burn card method, and introduces a major level of headaches. To computer-control complex LED lighting you have to go to sinewave control. Avail, yes.... expensive, yes,yes, yes.... subject to constant software upgrades and potential rapid hardware obsolescence too, yes! But if ya gotta try I, I do know how. But I'd wait a little longer, since LED is a lighting category rapidly evolving at the moment.

Egoltronics Multidodge contact printers (http://egoltronics.com/products.html). Hoo yeah! Also, the Log E enlargers.

Actually, with modern electronic kits, it's not too expensive. It's just that nobody wants it. A voice coil mirror controller operated scanning a laser diode beam across a negative would illuminate it just fine, and then it's a matter of telling the controller what gets burned or dodged. That could be done with a camera and a sheet of paper, to record coordinates for the controller.


Think you're getting a little close to X-Files reruns. There are already too many geeks wandering around this neighborhood with bar codes on the back of their necks!

I wonder if that's from 12 Monkeys, where it was an ID assigned to prison inmates.

[Drew Wiley]

Cute Brian.... So did you actually price one of those and then figure out how much more it would cost to turn it into a workable system for normal photography....
"not too expensive" is a relative term. And as far as big bertha film recorders, we've got those too... they're called Lightjets, Lambdas, Chromiras, etc.... not exactly
cheap to own and operate either. ... and not exactly a 4H project for some kid in the back of a barn with a soldering iron... LED programmable controls are already
in use to control all kinds of energy and decor variables in large-scale commercial lighting, and potentially apply to halogen or anything else. It's big budget stuff.
Try squeezing any more than three dimmer controls into an LED bank at the same time and see what happens ... a mess! I can automatically dodge black and white
for about ten cents a year. It's called neocreosin dye. Then for color it's called a masking punch. But with all these electronics devices planted in everyone's head
already (via subliminal web images and other Martian conspiracies), it's becoming impossible for the human race to do anything the easy way.

[Brian C. Miller]

I wasn't thinking of a LED dimmer, but a LED laser scanned across the negative. The LED doesn't have to be dimmed, just pulsed. This stuff was "old" when I was in high school. Unlike a film scanner, the requirements for a simple light source is quite a bit less. There's a number of tutorials for "hard drive laser oscilloscope" projects and such. As an electronics geek who became hooked in kindergarten, building stuff like this is fun.

The question is the initial cost. A precision film punch is not cheap, and one is needed for each format. So, a punch for 8x10 and 11x14, the contact holder, etc. and that adds up really fast. Contrast that with a controller, a couple of voice coil motors and 1st surface mirrors, laser LED, and sans programming time, its probably 1/4 the cost or less.

Mind you, this is using it just as a light source, not making a DIY film recorder. And it looks like the crocein dye needs amonia to remove it.

[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 (http://www.niceledlights.com) 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...

[cardiomac]

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

The problem with LED's is that commonly available, high-brightness units do not put out much light in the UV range where Lodima is most sensitive. High-brightness UV LED's are available but they are very expensive and require eye protection. Near-UV LED's at 405nM are relatively inexpensive and work OK, at least they require no eye protection. I have used them in a 4x5 diffusion lamp head for enlarging on to Lodima. Using 8 LED's at full power (about 24 Watts total), it takes about a minute to expose a typical 4x5 negative to an 8x10 print. The advantages are that there is no heat so there is no warping of the negative, the emitted wavelength of light passes easily through the enlarging lens, having a single dominant wavelength may improve sharpness through the lens, and no eye protection is needed.

[polyglot]

With longer wavelength UV (the cheaper UV LEDs), you don't have the "visual focus" / "chemicals focus" offset problem as with shorter wavelengths. And less of it will be absorbed by the glass.

[Tin Can]

Is that good or bad?



With longer wavelength UV (the cheaper UV LEDs), you don't have the "visual focus" / "chemicals focus" offset problem as with shorter wavelengths. And less of it will be absorbed by the glass.

[polyglot]

The longer wavelengths will be easier to deal with. For a start when you focus the print under the enlarger using visible light, you won't need to apply a focus adjustment and hope that you got it right. And your exposures are likely to be shorter for a given LED power. There's a reason that Nikon sells special quartz UV-Nikkors: glass lenses soak most of it up.

Think of sitting behind a glass window. You don't get sunburnt because the glass absorbs all the UV-B but the longer wavelength UV-A still comes through and (say you're a truck driver with chronic sun exposure through windows) turns you wrinkly.

[cardiomac]

The longer wavelengths will be easier to deal with. For a start when you focus the print under the enlarger using visible light, you won't need to apply a focus adjustment and hope that you got it right. And your exposures are likely to be shorter for a given LED power. There's a reason that Nikon sells special quartz UV-Nikkors: glass lenses soak most of it up.

Think of sitting behind a glass window. You don't get sunburnt because the glass absorbs all the UV-B but the longer wavelength UV-A still comes through and (say you're a truck driver with chronic sun exposure through windows) turns you wrinkly.

Good explanation.