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LED Enlarger Head - Update
As some of you may be aware, I have recently converted a DeVere 54 enlarger to LED lighting using the tri-colour PCB from an LED stage light.
Last night I finally got round to making some prints and I am very pleased with the results...... which I can't show you yet as I didn't have enough fixer!!! I made up a weak mixture with the little I had but all the prints I made have darkened. I will order some more and make some prints which I can show here.
Anyway, despite this, these are my observations:
The first print I made was with all three colours (red, green and blue) and all appeared to work well. I was worried about the spread of light and the diffusion not being enough and I was expecting to see the corners lighter than the centre i.e. reduced illumination at the edges. Actually it looks very even across the whole print so I don't think there is anything wrong with the diffusion I have used.
I then tried prints with just the green and just the blue LEDs. Both of these worked very well and showed low and high contrast as expected. Not at the extremes of 0 and 4 or 5 as could be achieved with normal filters but perhaps 1 to 3 or 3.5 (just guessing here).
The thing which surprised me was that for a similarly dense print I needed just over twice the time with green as I did with blue. I was expecting it to be the other way round.
Another surprise was the amount of light. As a guide, printing a 5x4 negative up to 10 x 8 with the lens two stops down, I could get a good print with around five seconds exposure time. I may increase the diffusion a bit to both reduce the level and to be sure of good light spread (even though I have already stated that it is ok!).
I will update this thread with some pictures when I get them.
Steve.
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Thanks for the update Steve. I was wondering about this very thing last night, and if the lens was working out for you.
Rick A
Argentum aevum
BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
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The lens is working fine thanks. Did those small, rectangular pieces of paper turn up in the post?
Steve.
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Oh my, yes they did. I converted them into liquid refreshment, as you said they would.
cheers
Rick A
Argentum aevum
BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
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 Originally Posted by Steve Smith
Did those small, rectangular pieces of paper turn up in the post?
Steve.
I think the technical term is "Beer Tokens", but I could be wrong.
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I remember sending Soupy Sales some of those "funny green pieces of paper" out of my mom's purse when I was a kid.
Maybe that's what he's talking about? 
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They were useful beer tokens at that. They were accepted at the local watering hole.
Worker, I did that too. My mom wasn't real happy with me for a while.
Rick A
Argentum aevum
BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
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Originally Posted by paul ewins
I think the technical term is "Beer Tokens", but I could be wrong.
I think I did refer to them as beer tokens in my covering letter!
Steve.
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Yes Steve, you did refer to them as "beer tokens".
Rick A
Argentum aevum
BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
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Originally Posted by Steve Smith
The thing which surprised me was that for a similarly dense print I needed just over twice the time with green as I did with blue. I was expecting it to be the other way round.
Someone on another forum has pointed out that I shouldn't be surprised by this as the nature of the blue sensitive higher contrast emulsion should build up density quicker than that activated by green light. For a fair test I should compare the times taken to get to a mid grey.
The next step is to get some new fixer and make some proper prints and lots of notes - something I don't often do but should!
I am then going to work on a switch mode controller with a single control so that fully anti-clockwise the duty cycle is 100% green and 0% blue. Turning the control clockwise will increase the duty cycle of the blue and reduce that of the green so at the mid point they both receive 50% and fully clockwise it is 0% green and 100% blue. This will give me a single Contrast control. I may also add an overal Brightness control. All I need to add are Horizontal and Vertical Hold controls and it will resemble a 1960s TV!
Steve.
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