LED Diffusion Lighthead for Omega D5

[denverjims]

In March I had the privilege to workshop with Alan Ross during which he spent time showing me the capabilities of the Ross Masking Technique. One of the things that became clear during our discussions was that this method would not work well with my D5 condenser lightsource. Not wanting to go back to the noisy and heat producing Chromega II head and having used a replacement LED source for the condenser head for some time, I began to search for a LED solution.

I am cold on cold light heads and, sadly, Modern Enlarger Lamps is not currently producing their Model 2. Finally, I was unable to convince my wife to sign the papers to take out a 2nd mortgage in order to afford the Heiland. As a result I went to Plan B which was to try to make one. Below are a couple of pictures of the Omega head so you can see what I needed to design to if I was going to build a replacement.

When I was in his darkroom, Alan showed me some details of his self-made LED head which we used a lot. The following design is adapted from many of the concepts and design ideas he so generously shared with me as to how it could be done.

My design parameters were: 1. It would be a ‘bolt-on’ replacement for my Omega Condenser head; 2. I would use filters (Ilford Multigrade, Rosco, [Arista] Color Printing Filters) for contrast control rather than a dial-in variable method; 3: It would use off the shelf LED components; 4) the negative holder for the Omega would still be used unchanged below the light source and 5. contrast filters would be above the negative.
164960164959
I have attached pictures to this post to illustrate my design and a spreadsheet to show the LED configuration and source.

Top to bottom the components are:

1. a simple box of wood which serves only to act as the place where the lever arms of the enlarger (which are used to raise and lower the condenser head) connect. This was made with 1x6 lumber (over kill but I used to work for AT&T when it was the phone company and we designed phones to last 100yrs).

2. the above is connected to the lid (7”x10”) of the contrast filter holder box. This lid has the LED strip lights mounted on it. I used 1/4 inch Masonite type board to which I glued a 1/32 inch sheet of sheet aluminum. Then I mounted the strip LED light to that. I used the aluminum to give a better surface for the strips to adhere to and to dissipate the LED heat more evenly.

The LED strip lights and the driver (power supply) I bought from FlexFire. Alan had used another vendor but I found that FlexFire had an ‘ultra-bright’ option which put out more lumens per foot. Alan’s head had 12x12 inches of LED strips for up to 8x10 coverage while mine was only going to be 6x8 inches for 4x5. I felt I would need the additional light output. The configuration of my strips and wiring diagram is included in the attached spreadsheet. Also on that spreadsheet is the call out for the FlexFire parts I used.

3. The filter box is mostly just that - a box. The bottom has a 5 1/4 x 5 1/4 inch hole which sits on top of the negative holder. Inside it, it has 2 components: a) at the top I mounted 3 sheets of .05 Mylar in between 2 pieces of window glass to act as the diffuser for the LED light coming down from the lid; and b) in the front of the box is a hinged door through which I introduce the 6x6 inch contrast filters which sit over the bottom hole.

Total cost of components, including LED lights and driver, < $300 US.

Put it all together and paint it black and you get the head shown. I works well so far (about 2 weeks into its use).

In testing, I found that the brightness was within 1/4 stop of the brightness my condenser head (using a Modern Enlarger Lamp 1a light source) so I was happy there.

The only place I was surprised was when I was doing my contrast calibration testing using the Steve Anchell methodology laid out in his “The Variable Contrast Printing Manual”. I first tested my Ilford Multigrade filters and found that, while they were spot on for grades 00 through 2 1/2, grade 3 to 5 filters were producing <3. When I switched to combinations of Rosco filters, I was able to achieve grades 3 - 5, however.

While the spectral output curves of the FlexFire look like they are adequate, apparently there is something missing in the part of the curve that Ilford uses to balance out the exposure factor for those higher contrast grades.

For me this will not be a problem as I was planning to change away from the Multigrade filters anyway. Using combinations of Rosco Magenta and Yellow filters and/or Color Printing Filters, one can achieve finer differences in contrast than the 1/2 grade steps using MG filters.

Hope this was not too confusing with pictures and feel free to PM me or ask questions through this thread about anything that was not clear.

[denverjims]

Below are some additional pictures of the final assembly on the enlarger. In the side view, the filter door is open with the light source on. PS, the light stripe over the door is not a light leak, it was part of the gray sponge material I used to seal the lid to the top of the filter box. I had not painted it yet.

Also, a couple of shots of the spreadsheet showing LED layout & wiring as well as the components I bought from FlexFire LED.

[denverjims]

I thought I'd add links to the FlexFire LEDs I used, their output spectrum and the power supply.
Also a useful YouTube video on how to cut and solder LED strips.

Strips:
https://www.flexfireleds.com/high-cri-93-series-ultrabright-led-strip-light-by-the-foot-natural-white/

Power Supply:
https://www.flexfireleds.com/12v-6-amp-72w-led-strip-light-power-supply/

Spectrum:
https://www.flexfireleds.com/content/UB-CRI-NW-12V-Test-Data-Summary.pdf

YouTube video:
https://www.youtube.com/watch?v=bTRLt-fzTwg&app=desktop

[radii]

Jim,

Very nice project and execution.

As far as the spectrum of the LED goes, did you look into using a mixture of green, blue and ultraviolet ones in lieu of the full spectrum ones?
Or would there be no benefit to it and the flexfire LEDs are the most even balanced ones out there?

How hot does the panel get, how far from the negative is it and how even is light at that distance?

Thank you

JP

[denverjims]

JP,
I did a cursory search but the color versions (at least for most I found) only had one color per strip and the lumens per ft. was less than the Ultra Brite's. Finally, I only had room for 11 rows of strips and I did not think I had enough room for each color to give a correct balance. (Translation: to do so would have required skills I don't have.)

As I said in my design spec, I was just looking for enough "white" light in the right area of the spectrum to be able to use Rosco and Arista Color Printing filters. The MG contrast filter issue did not bother me (although it did surprise me a bit). I tested them out of curiosity and I wanted to share this result with others in case they would plan to use them exclusively.

As far as being balanced, FlexFire advertises that they pick LEDs for each strip (up to 16') from a single mfg. batch so that they are balanced. Most of the other mfg. I queried specifically did not. It may be that some others do as well but I found FlexFire first and they had the Ultra Brite's with sufficient lumens at a fair price so I stopped looking.

The panel has not gotten hot or even very warm to the touch so far. Distance from the lid with the LEDs to the negative stage is almost exactly 4". I think if I were to make another, I would cut that distance down a bit. Using an Ilford EM-10 density meter, I could find no drop off anywhere in the illuminated field. That meter is not the most sensitive in the world but it is good to at least 1/4 stop. The 3 sheets of Mylar seem to have done the job in evening the light out. Also, I did several paper exposure tests with no neg and could discern no unevenness.

Hope that answers your questions.
Regards, Jim

[Kirk Gittings]

Sweet. Thanks for sharing this. Next time I am in Denver (some of my kids live there) I might want to see it first hand if possible.

[Pere Casals]

This lid has the LED strip lights mounted on it....

Thanks for sharing your project.

I'm also DIY making something like this. I plan to use RGB LEDs for contrast control, with 3 separate dimmers for each color, in order to avoid filters, and avoiding moving the head while exchanging filters for split grade, and later burning some areas with another grade.

I guess CRI is not important for BW contrast control, as you always end in some contrast grade, it's a matter of calibration.

The RGB LED source has the advantage that red filter is not necessary, just power on R channel...


Regards.

[radii]

JP,
I did a cursory search but the color versions (at least for most I found) only had one color per strip and the lumens per ft. was less than the Ultra Brite's. Finally, I only had room for 11 rows of strips and I did not think I had enough room for each color to give a correct balance. (Translation: to do so would have required skills I don't have.)

As I said in my design spec, I was just looking for enough "white" light in the right area of the spectrum to be able to use Rosco and Arista Color Printing filters. The MG contrast filter issue did not bother me (although it did surprise me a bit). I tested them out of curiosity and I wanted to share this result with others in case they would plan to use them exclusively.

As far as being balanced, FlexFire advertises that they pick LEDs for each strip (up to 16') from a single mfg. batch so that they are balanced. Most of the other mfg. I queried specifically did not. It may be that some others do as well but I found FlexFire first and they had the Ultra Brite's with sufficient lumens at a fair price so I stopped looking.

The panel has not gotten hot or even very warm to the touch so far. Distance from the lid with the LEDs to the negative stage is almost exactly 4". I think if I were to make another, I would cut that distance down a bit. Using an Ilford EM-10 density meter, I could find no drop off anywhere in the illuminated field. That meter is not the most sensitive in the world but it is good to at least 1/4 stop. The 3 sheets of Mylar seem to have done the job in evening the light out. Also, I did several paper exposure tests with no neg and could discern no unevenness.

Hope that answers your questions.
Regards, Jim

Yes, thank you for the thorough answer.
I had at some point thought about making a similar panel and was concerned about the spectrum, since traditional printing paper seems to be designed with incandescent light sources in mind. So a lot of work making a panel that will produce mediocre results ...and that the relative short distance to the negative would produce hot spots. It all seems to be working just fine though, as you have proven.

[denverjims]

Sweet. Thanks for sharing this. Next time I am in Denver (some of my kids live there) I might want to see it first hand if possible.

Sure Kirk, just let me know.
In fact come by on a 3rd Saturday of the month & join our LF group mtg. as well. We'd promise to be gentle. ;>}
Best, Jim

[denverjims]

Yes, thank you for the thorough answer.
I had at some point thought about making a similar panel and was concerned about the spectrum, since traditional printing paper seems to be designed with incandescent light sources in mind. So a lot of work making a panel that will produce mediocre results ...and that the relative short distance to the negative would produce hot spots. It all seems to be working just fine though, as you have proven.

Yes, I did consider distance for that reason but, inverse square law being what it is, I was trying to balance it out to keep it bright enough for reasonable exposures. With as many LEDs per inch as there were, and as tightly as I packed the strips, seemed to work.

Regards, Jim

[Chauncey Walden]

Jim! 2nd Saturday! Kirk, always welcome.

[denverjims]

Jim! 2nd Saturday! Kirk, always welcome.

Whoops! It's that thick Costa Rican air! Yes, 2nd.
(A contrite) Jim

[Tin Can]

Very good design and execution.

The parts are still available.

I missed this as I was not on the forum for months at that time.

Great post!

[Pieter]

Are there any issues using a conventional timer with LEDs? Start-up lag, flashing, etc?

[denverjims]

Good Questions.
1. No problems using conventional timer. Current load on timer very low due to LEDs and, in my design, less than a conventional 60 watt bulb.

2. Yes, there is a 'Start-up' lag. In the case of the LEDs and driver I used, it worked out to about .7 seconds. As a result, I need to add .7 on my timer to my calculated total time for the exposure. Once they are on, the time to full luminosity according to the specs is only a few milliseconds so I have not needed to adjust for that. The .7 second adjustment is a bit of a pain, but overall the advantages of LEDs make it very much worth it to me.

3. I have noticed/measured no flashing. Once the LEDs are on, they seem to stay at a constant luminosity.

Unasked:
Do you have to 'warm' the LEDs & driver up with some 'on time' before the actual exposure?

My Answer:
I have not added any warmup for each exposure. I was told, by the manufacturer, that the first time you turn on the LEDs after some hours of disuse, there may be a need to have them on a few seconds to reach full luminosity. However, since I usually have them on for that time (at least) to confirm proper focus of the negative at the start of each darkroom session, I have not done anything special for this issue. Nor have I done any preliminary 'on cycles' for subsequent exposures within a darkroom session. Seems to work fine.

I am still using the Version 1 of the lighthead that I documented in this post - even now. I had expected I'd need to build a V2 to get to a final, fully usable one but so far, so good. Even blind pigs...

Hope that helps, Jim

[denverjims]

Very good design and execution.

The parts are still available.

I missed this as I was not on the forum for months at that time.

Great post!

Thanks, Randy.
Best, Jim

[Pieter]

Good Questions.
1. No problems using conventional timer. Current load on timer very low due to LEDs and, in my design, less than a conventional 60 watt bulb.

2. Yes, there is a 'Start-up' lag. In the case of the LEDs and driver I used, it worked out to about .7 seconds. As a result, I need to add .7 on my timer to my calculated total time for the exposure. Once they are on, the time to full luminosity according to the specs is only a few milliseconds so I have not needed to adjust for that. The .7 second adjustment is a bit of a pain, but overall the advantages of LEDs make it very much worth it to me.

3. I have noticed/measured no flashing. Once the LEDs are on, they seem to stay at a constant luminosity.

Unasked:
Do you have to 'warm' the LEDs & driver up with some 'on time' before the actual exposure?

My Answer:
I have not added any warmup for each exposure. I was told, by the manufacturer, that the first time you turn on the LEDs after some hours of disuse, there may be a need to have them on a few seconds to reach full luminosity. However, since I usually have them on for that time (at least) to confirm proper focus of the negative at the start of each darkroom session, I have not done anything special for this issue. Nor have I done any preliminary 'on cycles' for subsequent exposures within a darkroom session. Seems to work fine.

I am still using the Version 1 of the lighthead that I documented in this post - even now. I had expected I'd need to build a V2 to get to a final, fully usable one but so far, so good. Even blind pigs...

Hope that helps, Jim

I asked about the timer and flashing because I set up a small electroluminescent panel to flash paper and had to add a dummy load or the panel would pulse when off as long as it was connected to the timer. Also have a lag, but I have been able to compensate since the flashing time is always the same--I only use one paper right now.

[denverjims]

I asked about the timer and flashing because I set up a small electroluminescent panel to flash paper and had to add a dummy load or the panel would pulse when off as long as it was connected to the timer. Also have a lag, but I have been able to compensate since the flashing time is always the same--I only use one paper right now.

Pieter,
No, I see no flash of any kind either during or after timer operation with my setup. The timer I am using is an old Ilford DT600 (previously a Creative Phototronics Touch Timer). (Note: The one picture I found on the web (below) is of the programmable version. The one I am using is the straight, non-programmable one.)
184448

Sounds like you did figure it out, though. I'm no electronics guru but sounds like the timer you are using was set up to operate loads much larger than your panel. The additional load you added probably compensated for this. Maybe someone else, with more expertise on the subject, might have better insight.

Finally, the .7 seconds lag in my setup is, to my best perception, constant. I just don't know if this interval is a general constant with that combined type of LED and driver or if it would vary by driver or by the number of LEDs one would use in the configuration.
Best, Jim

[Paul Ron]

Im using the rosco filters with my cold light. They're very thin, I laminated them so they'd be nice flat in my holders. My only disappointment with the filters I mail ordered from B&H, they were in terrible condition, wrinkled n damaged as if they were used as floor mats in their warehouse. I had to go to the store to get nice ones.

[jp]

The .7 second lag might be the power supply If your timer were downstream of that, there might not be lag.

[m00dawg]

Great post! I've been pondering how to switch my D2 to a diffusion enlarger and this seems like a good way to go! To jp's point, the lag is probably the power inrush from the AC to DC power supply for the LEDs. I think you could fix that by using a relay controlled from the timer. So the timer is turning the relay off/on which would open/close the DC side of the circuit where the LEDs connect to. That keeps the LED power supply itself ready to go.

I haven't found a relay that is for switching a lower voltage using a high voltage for the switching though I'd imagine they exist (that or perhaps a transistor).

My concern here is those Ilford MG filters. I've gotten quite used to those so matching the wavelength there would be ideal. I wonder if warm-white LEDs might be closer in spectrum? I think the multicolored LED solution might be the best option. I think that's what the Intrepid 4x5 enlarger uses (actually wondering if I can augment their head on my D2...). And/or I wonder if RGB LEDs would work (you can find pretty dense RGB LED strips if space is tight, though not sure about light output). I'd still prefer filters over fiddling with colors. I think I would need/want a much more intelligent timer where I could easily dial in the desired filters for me to be happy with not using the gel filters.

In the interim, I read up a bit on making a diffusion panel for the Omega D2. I'm guessing something as simple as rice paper would either not provide even lighting or would transmit too much texture? If not, placing that on top of the negative carrier would work in a pinch?

I love the condenser look when it works but man can it be contrasty. Spotting hasn't been a huge issue (so far) but I definitely get more dust than I did on my Beseler 67. My tiny darkroom doesn't have room for two enlargers (and I prefer to print 4x5 most of the time anyway).

[ic-racer]

I read up a bit on making a diffusion panel for the Omega D2.

I'd consider a Chromega D head to convert an Omega enlarger into diffusion. There are still bargains to be had on ebay, seeing as the filters don't fade. I have a 'spare' D size head for my Omega enlarger already, but if I didn't I'd pick up another Chromega D while they are still available.
The longer lift rods you need to mount the Chromega head are at any USA hardware store.

185255

[m00dawg]

I was looking at those, but they require a special control box as well correct? I was having trouble finding both for a reasonable price.

[ic-racer]

I was looking at those, but they require a special control box as well correct? I was having trouble finding both for a reasonable price.

The most economical power supply 412-021 is basically just a transformer in a box. Although the ELC lamp is a 24 volt lamp, it is my understanding that the transformer actually supplies 22.5 Volts to give a longer lamp life.

The fan and panel lamp operate on 120V, so the 120V is just passed through.

There are no other electrical or electronic components in the box with transformer.

[ic-racer]

I was looking at those, but they require a special control box as well correct? I was having trouble finding both for a reasonable price.


The 412-021 is the Standard Power Supply and is the most economical solution. It is basically just a transformer in a box. Although the ELC lamp is a 24 volt lamp, it is my understanding that the transformer actually supplies 22.5 Volts to give a longer lamp life.

The fan and panel lamp operate on 120V, so the 120V is just passed through.

There are no other electrical or electronic components in the box with transformer.
185257

[denverjims]

I'd consider a Chromega D head to convert an Omega enlarger into diffusion. There are still bargains to be had on ebay, seeing as the filters don't fade. I have a 'spare' D size head for my Omega enlarger already, but if I didn't I'd pick up another Chromega D while they are still available.
The longer lift rods you need to mount the Chromega head are at any USA hardware store.

185255

I had used the Chromega D diffusion head before I went to the Modern Enlarger Lamps (MEL) condenser LED head. It did the job and infinitely adjustable, dial-a-contrast was very nice.

However, the main things for me were that the constant fan noise was driving me to distraction and the heat from the lamp would quickly warp the negative as it heated up (I did not want to use a glass negative carrier due to the 4 additional surfaces that would need to be cleaned). If you can deal with these issues, I'd go with that solution because, as ic-racer said, there are heads available at pretty reasonable prices now-a-days. You WILL need the longer lift rods if you do.

I was mostly satisfied with the MEL head as it solved both of those problems for me with a 'bolt-on' solution. I'm a decent housekeeper so dust was not an insurmountable isssue. However, as I stated in my original post, I wanted to start using Ross masking method which requires a diffusion head. That's what took me down this build path.

Best, Jim

[ic-racer]

The thread indicates "D5" and I read it a number of times without seeing; the pictures are so small I did not notice you using this on a D5500 chassis. I use those with the D5500 color head. I have 3 heads and 3 controllers and enough spares to make one more head. This is one of those threads I'll save as a reference. If I made a LED head like that I think I could fit it in one of my spare D5500 head shells.

185262

[denverjims]

The thread indicates "D5" and I read it a number of times without seeing; the pictures are so small I did not notice you using this on a D5500 chassis. I use those with the D5500 color head. I have 3 heads and 3 controllers and enough spares to make one more head. This is one of those threads I'll save as a reference. If I made a LED head like that I think I could fit it in one of my spare D5500 head shells.


Hi ic-racer,
Actually, I'm not sure that I stated this but my enlarger is officially an Omega ProLab II. After the failure of Omega to capture a significant market with the automated D5500, they introduced the ProLab II enlarger which was essentially a D5 lamp housing and negative stage mated to a D5500 column. See KEH's description here (http://www.khbphotografix.com/omega/Enlargers/PLII.htm).

I typically call it a D5 because that's the compatibility model most folks know. I felt that the fact that it was a ProLab II not relevant to the project. Sorry for the confusion.

Best, Jim

[ic-racer]

No confusion, just a belated "congratulations for having what I think is the best 4x5 enlarger Omega made." It was a great system, allowing both the lift or cassette style negative holders and automated or manual heads.

[ic-racer]

Just so others that are not familiar with these enlargers know, a LED head like you constructed can sit right on the cassette negative holder and be bolted to the cassis. In that case the lift mechanism is not needed.
185309

[m00dawg]

The 412-021 is the Standard Power Supply and is the most economical solution. It is basically just a transformer in a box. Although the ELC lamp is a 24 volt lamp, it is my understanding that the transformer actually supplies 22.5 Volts to give a longer lamp life.

The fan and panel lamp operate on 120V, so the 120V is just passed through.

There are no other electrical or electronic components in the box with transformer.
185257

Late to reply (sorry) but that makes sense. Something I could probably build even if I couldn't find the box, but curious - it may sound silly, but how do you then adjust the filter amounts? It looked like some of these heads required a separate control thinger?

[ic-racer]

Late to reply (sorry) but that makes sense. Something I could probably build even if I couldn't find the box, but curious - it may sound silly, but how do you then adjust the filter amounts? It looked like some of these heads required a separate control thinger?

The Chromega head is all mechanical in the filter control. The other power supply you may have seen is the Chromegatrol, which is a combination of the power supply and a built-in timer.

The D5500 (that I have) uses electronic control of the filters with servo motors. The controller boards have many discrete components, so it is somewhat sustainable in the right hands.

[m00dawg]

Oooh ok. Yeah I was looking at the Chromagega D or some such and didn't see that there are knobs on the bottom :) Finally found the manual for one of those. I think I still have a bias towards a diffusion system that just lets me use filters. Seems like having to dial in filter amounts when doing split grading would get old pretty fast but the prices for these things aren't too bad used. I could go back to figuring out an under the lens solution I suppose. I used Ilford's under lens system that clamps onto the lens, but it doesn't fit on half the lenses I use with my D2 so I'll need to figure that out.

[ic-racer]

Just the diffusion system in the Chromega is/was state of the art. The mixing boxes ("Light Multipliers") have fancy diffusion panels that are thinner at the corners to even the light. There IS a filter slot also. I have seen Chromega heads with broken built-in filters given away (to me in fact :) ).
185524

From the manual:


Should you ever wish to use supplementary filters for special effects, etc., the space under the light multiplier accepts standard 5"x5" color printing filters, separation filters, etc.

[m00dawg]

Hah I must've missed that when reading the manual! Well that sounds pretty great!

[Daniel Unkefer]

https://live.staticflickr.com/65535/48410140211_368265af78_z.jpg (https://flic.kr/p/2gKQC6R)Printing with new E3 (https://flic.kr/p/2gKQC6R) by Nokton48 (https://www.flickr.com/photos/18134483@N04/), on Flickr

Today I disassembled and rebuilt the LED head I received with my Automega E3. I mounted the LED driver on top of the head (as Jerry Bodine did) which gives more room inside for spreading out the diffusion plexi inside and now it's pretty even. Using my Pentax Digital Spotmeter I can see the center is 1/3 stop brighter than the four corners. I can live with that.

So tonight I am printing through 5x7 glass carrier with the E3 and the LED :)

[Daniel Unkefer]

https://live.staticflickr.com/65535/48413617242_6224712943_z.jpg (https://flic.kr/p/2gL9rGE)5x7 E3 LED test 1 Norma TMX100 PMK+ (https://flic.kr/p/2gL9rGE) by Nokton48 (https://www.flickr.com/photos/18134483@N04/), on Flickr

https://live.staticflickr.com/65535/48413471321_482ebe23c6_z.jpg (https://flic.kr/p/2gL8GjM)5x7 E3 LED test 2 Norma TMX100 D76 (https://flic.kr/p/2gL8GjM) by Nokton48 (https://www.flickr.com/photos/18134483@N04/), on Flickr