Beseler 23C 4x5 modification, DIY LED head

[konakoa]

Hello folks,

I'd like to share a modification to a Beseler 23C I've made to make it a very compact and light weight 4x5 enlarger. I've also made a LED head for it that may be interesting. I wanted to detail and show my decision process along the way, so I created a webpage with text and photos describing what I did. It can be seen at:

www.deadbread.com/crumbs/23c.html

I'd be very interested to hear any thoughts or suggestions!

 

[Paul VanAudenhove]

Wow! That's very impressive! Can you give me an idea of the total time and parts costs? I might search for an old 23C....

 

[Denis P.]

Danny, that's brilliant!
A very useful source of info for all of us DIY-ers

I think I can even see a 5x7 enlarger built this way....
Hmmm...

 

[konakoa]

Paul - from beginning to end, about a month and a half. It took awhile as there were several delays for shipping time and backorders for parts. If everything was immediately on hand, I'd say about four days. The biggest time consumer was milling out the negative stage - a full day. The rest was a snap in comparison.

As for costs, I spent about $700. It would be substantially less if you already had a lens, existing enlarger, etc. My costs were higher as I bought a lot of brand-new parts. Considering a brand-new 4x5 is upwards of $1600 and is far bulkier and heavier than my modified 23C, I didn't think it was too bad.

 

[konakoa]

I neglected to mention printing times. With the lens at f/11, 8x10's are around 5 seconds. 11x14's in 7 seconds. Those times are with VC filters in place. The LEDs are bright!

If the photographs on the site aren't clear or anyone needs a more detailed view, please contact me - I'd be glad to provide larger photos.

 

[Paul Goutiere]

Hello folks,

I'd like to share a modification to a Beseler 23C I've made to make it a very compact and light weight 4x5 enlarger. I've also made a LED head for it that may be interesting. I wanted to detail and show my decision process along the way, so I created a webpage with text and photos describing what I did. It can be seen at:

www.deadbread.com/crumbs/23c.html

I'd be very interested to hear any thoughts or suggestions!

Hello,
What a superb idea. I wouldn't think it would work but there it is. I do have a small suggestion if I may:
If you would like the leds to go out immediately, put a switch between the power supply and the leds. There is a component in the power supply (called an electrolytic capacitor) that will store some voltage for a while.Bypass this and the leds go out immediately. Just in case no one else has suggested this.
paul

 

[jstraw]

Not counting a switch and the materal to build the housing's case, the materials for a 6x6 unit for my Beseler 45MXT comes to about $140. Wow.

How would one operate the 12 volt line via a timer, rather than a switch if the timer is passing 115 volts? Since plugging the ac adapter into the timer would have the capacitance issue....

 

[Nicholas Lindan]

www.deadbread.com/crumbs/23c.html

The delay with the LED's turning off can be fixed with a relay. Get a 120V 60Hz coil relay from Radio Shack and wire the relay contacts between the LEDs and the power supply. Leave the power supply plugged into the wall all the time, it won't draw any power if it is disconected from the LED load.

 

[jstraw]

The delay with the LED's turning off can be fixed with a relay. Get a 120V 60Hz coil relay from Radio Shack and wire the relay contacts between the LEDs and the power supply. Leave the power supply plugged into the wall all the time, it won't draw any power if it is disconected from the LED load.

Then the relay is connected to the timer?

 

[Curt]

Hi Danny, do you think the strips could be cut in order to arrange them for a 5x7 head? Or do you think that your design could be added to by putting extra strips around them?

Curt

 

[Curt]

I also noticed that the LEDs come in both 7000k and 3000k strips. Variable contrast head? Dimming of LEDs and edge burning possibility in the array?
Lots of questions.

Curt

 

[wirehead]

Well, it wouldn't be very hard to hack up an LED VC-light source that would let you select the grade digitally. No more futzing around with filters.

In fact, I've probably got most of the necessary bits sitting on my desk right now.

 

[konakoa]

Paul, Jstraw, I simply have the wall transformer for the LEDs plugged into a GraLab 450 timer. For what it's worth, the GraLab is advertised as capable of handling inductive (fluorescent tube cold light) loads. I'm not sure if that pertains to the little AC/DC transformer for the LEDs, but so far I haven't had any problems with either the timer or transformer.

The wall transformer I got from LEDtronics has the following rating: AC input 120 volts, 0.25 amps. DC output 12 volts, 1 amp, 12 watt maximum. The GraLab 450 just lists the following maximum loads: lamp 600 watts, or a resistive load of 1,200 watts.

I'm glad to see some solutions to the LED 'fade'. I can best liken it to printing with a color head -- the fade of light from the bulb when it's turned off. I'm not too sure of myself to be dabbling with delicate electronics, so I've just been incorporating the 'fade' into the printing time. For me, it's nothing more complicated than making a test strip, deciding on a good time, then making a working/final print in the exact same manner and time as the test strip.

 

[konakoa]

Curt, I chose the 7000K strips as according to the manufacturer they're the brightest they offer. The 3000K LEDs are much dimmer, about 1/4 as bright if I read their charts correctly. Using both wouldn't offer VC (7000K blue-white and 3000K dull yellowish color) and would get into problems with the brightness difference between the LED modules. The modules are one unit; and as my limited understanding of electronics goes, the LEDs are connected in series. I don't see a way to control each individual bulb for dimming and edge burning as you describe. Any dimming of the light would have to be applied to the entire strip of 12 bulbs.

I think a larger 5x7 might be possible. I don't think the modules can be cut (at least I wouldn't!) as I see resistors built into the circuit boards of each strip every three bulbs -- I have no idea what cutting into the module would do to it. However, I think the 6" modules could be rearranged for a 5x7. Offhand I figure the head will probably have to be taller than the 4x5 I've built (to better diffuse the light out to the edges) and will need more than six light strips. I'll tinker with my setup and let you know ASAP about 5x7.

 

[wirehead]

Hrm.

You could always try wiring up the all transformer through the GraLab on the 12v DC side....

Also (and I can walk folks through it if they want) you don't need to buy a strip, you can just get a perfboard from Radio Shack, some resistors, and some bare LEDs and make your own modules. Should be able make modules to fit any size that way.

 

[Curt]

Thanks all for the excellent answers to my questions. I am quite excited about the possibilities of using LEDs for a diffused light source. I was already looking for loose LEDs as wirehead had noted about making a board for use instead of strips. The strips though would simplify the work and seem to be a very good and well thought out process. A relay would be worth looking into with use of my existing timers.

Thanks
Curt

 

[jeroldharter]

I think that someone here who is handy with electronics could make some money if he built a relatively cheap VC LED light source that was adaptable to the standard enlargers. The Calumet is > $1500 which seems awfully expensive for turning blue and green LED's off and on.

I suppose the easiest way is to use the white LED strips mentioned here and then use below the lens glass filters for split contrast printing, but a head with both blue and green filters would be nice.

 

[Lee L]

I think that someone here who is handy with electronics could make some money if he built a relatively cheap VC LED light source that was adaptable to the standard enlargers. The Calumet is > $1500 which seems awfully expensive for turning blue and green LED's off and on.

I suppose the easiest way is to use the white LED strips mentioned here and then use below the lens glass filters for split contrast printing, but a head with both blue and green filters would be nice.

Jerold,

I've been thinking about construction a light source for my D5 similar to the one in this thread, but using strips of blue and green LEDs from superbrightleds.com that are similar to the white ones used here. They have two kinds (one that snaps into shorter lengths) and they use half as many LEDs in the same space as the units in this thread. Given the times reported here, that light loss wouldn't be too problematic. UV or deeper blue LEDs might get more contrast.

Lee

 

[jstraw]

Do these LED's require any filtration in addition to VC filters? What is the right color temperature for a VC light source?

 

[konakoa]

I haven't needed any filtration with the white LEDs other than my standard VC filter set. The light from the LEDtronics modules is a blue-white. Unfiltered, this light is the equivilent of a grade 3 (best guess) on my papers -- Kentmere VC RC and Agfa MC FB.

5500K is 'daylight' and most tungsten/halogen bulbs are around 3000K. I suspect the right color for VC could be just about anything we want, just so long as we can get enough green, blue and UV in the mix that our papers are sensitive to.

 

[wirehead]

Well, like I said, I've got the bits on my desk to make a LED VC head.

I'm pretty sure that you'd be able to do it with stock parts and a microcontroller. Instead of white LEDs (which are not as efficent as the advertisers would like to think) you should just use blue and green LEDs.

Depending on sensitivity, you should be able to use the three-color-in-one-pacakge LEDs, which reduce the uneven-color-distribution problems and lets you have a "safelight" mode or lets you use it as a color head too.

There's a lot you could do with it, mind you. Imagine programming in a split-tone pattern with x seconds at grade 0, y seconds at grade 2, 10 seconds of safelight so you can grab your dodging tools, and then z seconds at grade 4 in a box that, as far as the parts are concerned, costs under $50.

 

[Curt]

I'm pretty sure that you'd be able to do it with stock parts and a microcontroller. Instead of white LEDs (which are not as efficient as the advertisers would like to think) you should just use blue and green LEDs.

Hi wirehead, can you give me a lead on where to buy LEDs? I think I will put together a light source for my small 6x6 enlarger to experiment with. I need to have my Beseler 45 in operation or I would use it.

Many thanks to all the folks here. If anyone else is going to experiment or make one would you please post the info here?

Curt

 

[konakoa]

Curt, I dabbled around and I'm reasonably sure a 5x7 could be made from the LEDtronics modules. I made up a outline and I'm including a side view of my existing 4x5 head you might be able to use. I'm posting it here for everyone, however please keep in mind it's experimental. The last thing I want to do is cause anyone here grief.

The design is based off my 4x5 -- all I've done is add four more modules to the end of the head for a total of ten 6" strips. Ten modules creates a total of 120 LEDs (cripes!). Printing times would probably be something like two seconds. Something in-line to dim the bulbs (a rheostat?) would be useful. Also, with that many bulbs some kind of ventilation would probably be a good idea; perhaps nothing more than some open slits in the sides of the box with light baffles for passive cooling.

Superbrightleds.com (posted earlier by Lee) has some neat alternatives to LEDtronics. Also, a completely custom made light, like wirehead's suggestion, might be more practical for a 5x7.

 

[Curt]

Danny,
Thanks, I have been brushing up on my basic electronics and looking at some LEDs. This is the kind of project that I would enjoy putting together and the strips are a good way to get going right away.

Curt

Thanks so much for the diagram and picture.

 

[Steve Smith]

Thanks for posting these details. I have been thinking about making a 5x4" enlarger and an LED light source seems to be the best way to do it. I may also do some experiments with alternate green and blue LEDs.

Steve.