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LED Split Printing Enlarger Lamphouse

Mal Paso

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Not having quite enough spare change for the Heiland light source I am working on one of my own. I bought an old nonfunctional Beseler 45 Cold light head and striped it down to the main casting. The diffuser wasn't great and was replaced with light table plexiglass. I'm using Cree Leds. Blue and green for split printing variable contrast paper, red for white light to focus. The LEDs are attached with screws tapped into 1/4" aluminum plate with thermal grease in between. I finally got the LEDs mounted and wired today. I still have to build the switching for timing the blue and green LEDs and an all on for focus. I have about 54 watts total power dimable about 3.5 stops. As soon as I get switching/timing built I can start darkroom tests to see how even the light is and how much power I have. Diffusion eats light,

,I seem to have bollixed the editing but here is the blue.
 

koraks

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Looking good, it'll work like a charm I bet! If you want to go the fancy route, you could implement micro-processor controlled pwm to mix blue + green in appropriate ratios to achieve any contrast grade in a single exposure, but perhaps you're doing a pure split grade approach like Heiland does. I went for single exposure since I dont split grade much (virtually not at all in fact).
The nice thing about diy is of course that you can make the system perform exactly how you want it to. There's no single right or wrong way to do it.
 

RalphLambrecht

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Great job!
 
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Mal Paso

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I'm using the same LEDs and Drivers as JB Harlin. 6 each of the XT-E Royal Blue and XP-E2 Green and 7 of the Red XP-E2s to match power. I added Red for white light focusing but that may be unnecessary as Blue/Green looks good but it's already done. Playing with a single diode I found edge lighting to be the biggest problem so I lit the edge and filled the center. Looks OK on a spotmeter but the real test will be on paper with no negative. Here is the LED array on 1/4 inch aluminum.
Look at all the spots. LOL
Since I am working with the Beseler form factor I made the mounting plate to fit inside the old head so I could adjust the distance to the diffuser. For diffusion, a light source larger than the negative is better. Beseler is designed around 6.5 inch condensers and the best bet might be to remove the upper bellows assembly and build an oversize square light source but I'm hoping this will work. If it does the 1/4" aluminum plate that holds the LEDs will be bolted to a heat sink.

Hope to get the switching built today.
 
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Mal Paso

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Here's the temporary control center Hollywood style, false front. I added a relay to plug into my timer and a switch to turn off green or blue. I didn't have a 3 pole switch for white light, I'll order that in a minute. I need to build a shelf for the controller in the darkroom and move it in.
 
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Mal Paso

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I got it installed and made a test print with just blue, should be grade 5. I focused with a negative then pulled the carrier and made an 11x14 of just the diffuser. The exposure was 1 sec at f45 at 35% power for a medium grey. It's not perfect, a little hotter in the center, but good enough to start making prints.

The red LEDs (with the green and blue) were little help focusing and will be replaced with white.

Tired LOL
 
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Mal Paso

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Last post I had the green off by mistake, focusing is OK with RGB but I will still switch red for 3000K white. RGB full on is just too red.

Just had a printing session and I had to turn it down to 25% output to get an exposure of 3.2 seconds at f22, 4x5 negative printed 9x12 on 11x14 Ilford Classic.It was a landscape of Pt Lobos from 1972 that had a scratch on the back. The scratch is GONE and the tonal range is beautiful. I need longer exposure times before I can dodge and burn though. I will short the center diodes to see if I need them and maybe add more diffusion.

I am really pleased. As soon as I can set up the copy stuff I'll post the prints, I need a digital copy station at some point.
 
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Mal Paso

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Further away produces artifacts. It may have to do with the circular lamphouse and the white paint I used inside. They go away the closer the array is to the diffuser but overall coverage is less even. I'm kind of stuck with the dimensions unless I remove the upper bellows assembly. I am trying for perfect but it's pretty good now. You can barely make out the LED pattern on the grade 5 print of the diffuser only.
 

ic-racer

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Mal Paso said:
I need a digital copy station at some point.
Click to expand...

I use a "red filter" attachment on my enlarger and created a little cradle for my iPhone. Using that I don't have to remove the head of my enlarger to turn it into a copy stand. I also found my printing frames hold the processed prints just fine too. I bring in two lights in from the side. Don't for get to turn off the regular darkroom lights. I was getting a reflection and moved the side lights all over the place to get rid of it without success. Then I realized the reflection was from the overhead light that was still on

Using the iPhone works so well for me, I don't use a scanner for anything anymore.

Again, the iPhone is just sitting on a cradle hanging from the 'red filter' post on my enlarger's lensboard.

 
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john_s

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Mal Paso said:
...... It's not perfect, a little hotter in the center, but good enough to start making prints......
Click to expand...

I have an Aristo VCL4500 (2 "neon" or flourescent tubes) on a Beseler 45 and it's noticeably hot in the centre. Normal procedure to burn edges rectifies, but uniformity would have been nice.
 
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Mal Paso

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john_s said:
I have an Aristo VCL4500 (2 "neon" or flourescent tubes) on a Beseler 45 and it's noticeably hot in the centre. Normal procedure to burn edges rectifies, but uniformity would have been nice.
Click to expand...

I'm going to short the 2 center diodes to temporarily take them out of the circuit and print the diffuser at grade 5 again and see how even it is. I still have enough 1/4" aluminum to make another disk if I find a better layout of diodes. They generate too much heat to run them without a heatsink.


Very Cool! If I could knock out a wall for the right hand light...... I still have the frame of my first Beseler 45 in storage up north and was thinking of setting that up in the print finishing shop. The printhead went up in the Soberanes Fire but it has a 25 inch vacuum easel for a baseboard. I have a small mill for making an adapter. All the shows require electronic submission so I have to digitize all my analog submissions. LOL I found a clean 45 MCRX over in Modesto for $325 with the now $900 stand included, it was the fastest way to get going again.

Thanks!
 
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Mal Paso

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This morning I put a loop of tape over the center diodes and made a test print of the diffuser, no neg. The center was perfect. I disconnected the center diodes, cut a second diffuser, installed it and made a second print, awesome!

The working configuration now is 5 LEDs each of red green and blue 24 degrees apart around the edge of the aluminum plate heatsink with 2 layers of 1/4 inch color code 2447 acrylic for the diffuser.

After thinking about it I am keeping the red for positioning dodge and burn tools.
 

koraks

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The heiland controller automatically switches on only red when you enter burn mode for a few seconds and then goes to blue/green. That allows the user to position dodge tools.
 

john_s

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john_s said:
I have an Aristo VCL4500 (2 "neon" or flourescent tubes) on a Beseler 45 and it's noticeably hot in the centre. Normal procedure to burn edges rectifies, but uniformity would have been nice.
Click to expand...

Actually, thinking about this, evaluating the uniformity of illumination, I've always doe this by using the enlarger set up to do a print (lens focussed) then without a negative, but it occurs to me that the natural falloff of illumination of the lens might be causing my apparent hotspot. So maybe I don't have a hotspot after all, just lens falloff (unavoidable physics) possibly worsened because I use a slightly shorter wide angle lens in order to deal with low ceiling height.

So maybe, OP's idea of shorting the central LEDs is creating a "coldspot" which is an improvement over perfectly even illumination?
 
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Mal Paso

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Cool! I don't have much info on the Heiland, Thank You! I was looking at my first print with the LEDs and figuring out the burn when I thought of it. I'm thinking foot switches too. One red one timed blue green. And a 4 channel timer. The switching is done through the BuckBlocks, they are on all the time with the dimmer leads Closed until exposure. When the timing switch opens a resistor across the dimming leads controls the amperage through the diodes. Right now I have a 120V relay plugged into my timer that breaks the blue and green circuits.

The last print look great! The quality of light is very good and stable. The LEDs are running on a 24V power supply further regulated by the BuckBlocks. I could print with the heater running. LOL
 
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Mal Paso

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john_s said:
So maybe, OP's idea of shorting the central LEDs is creating a "coldspot" which is an improvement over perfectly even illumination?
Click to expand...

Removing the center diodes resulted in even lighting edge to edge (with my El Nikkor 135mm). Adding a second diffuser removed artifacts around the edge.
 
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Mal Paso

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Here are the prints. They are light on the left side from stray window light, still don't have a copy setup. The tonal range was exaggerated in Photoshop, the variation in illumination was more subtle than shown. This is blue only with the original 6 diode setup.


This is 5 blue diodes around the edge.


This is 5 diodes with 2 diffusers.


The three pole white light switch arrived and 2 foot switches are on the way.
 
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mshchem

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That's a great idea.
 

mshchem

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Looks awesome.
 
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Mal Paso

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I just got out of the darkroom, prints are in the washer. I tackled an old negative from Pt Lobos of a hillside in open shade above the ocean. You could have clouds, shadows or mud. I exposed for the clouds in the sky and completely dodged the shaded hillside during the green exposure so it only got blue light (grade 5). The effect was amazing, you see all the rocks and trees on the shaded hillside as they were printed higher contrast at a reduced exposure than the rest of the grade 2 print. And you can't tell, just like Paul Wainwright said.

Oh, there was a scratch on the back of the negative, no trace on the print.

I spent $40 for a defunct Beseler Cold Light Head and about another $200 on the parts that make up the final design. If I hit the jackpot I'll likely get a Heiland but this is Very Cool!

I made separate prints of green and blue exposures, they show how multigrade works, will try to post.
 
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Mal Paso

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I forgot to mention power levels. My experience with diffusion heads was long exposure times, wide apertures The original Beseler tube was 35 watts florescent, The LED head is about 46 watts at full power and is about 1.5 stops faster than the Condenser Head when the LEDs are at 25% power. The 11x14 print exposure was 8 seconds at f22 for each color, 4x5 negative. I will try some 120 and 35 negatives later today

The controller is still evolving. Red is going on a foot switch as well as a 3 pole switch for combined red/blue/green for focusing. I think the second foot switch should be burn, hand selected for blue or green. I'll trigger exposures by hand as 3 foot switches might be a little much. My old setup was exposure/burn.

LEDs are about 50% efficient, That means they are a 23 watt heater and at full power the aluminum plate that holds the LEDs gets warm. The conventional Condenser Head used a 150 watt bulb that was 5% efficient and generated 142 watts of heat which is why there is Infra Red absorbing glass in the condenser system to keep the negative from frying.

I am grateful to those who posted their LED conversions and thoughts, Thank You.
 
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Mal Paso

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The controller now has a foot switch for red, a 3 pole switch for all on white light and a 3 pole relay with one pole switching off the safelight while the print LEDs are lit. I took the center 2 red diodes out of the circuit so it's 5 of each color now. Last print session the exposure was 13.8 seconds at f16, 4x5 neg, 11x14 Multigrade print, at 20% on the scale which is 3% above just on. At some point I would like better calibration of the dimming and an automatic 80% on for all diodes when focusing. I printed a 6x6 neg yesterday without problems. My fears of an underpowered unit were unfounded but having full power to focus is awesome. I can see the image on the black arms of my easel.
 
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