The most ideal enlarger light bulb for some?

David Lyga said:

One thing that I feel is certain: if you use a graded B&W paper, the spectrum CANNOT matter, as all you are doing is projecting an image that is generated from pure silver and ONLY silver. Disagree? State why. - David Lyga

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The spectrum does matter, as graded paper will react differently to Red or Violet in terms of exposure, even if not in terms of contrast. In the same way that silver emulsions react differently to sunlight during the time of day.

guillermo alvarez said:

I have been using this light bulb for about a year now and I am really happy with it. It has the exact same form as the traditional light bulbs and the light distribution looks quite even to me.
I have a Durst M670 SW with the condenser for 6x7 negatives + EL-Nikkor 80mm

https://www.obi.de/e27-led/osram-le...ar-e27-12w-1521-lm-kaltweiss-eek-a-/p/8471229

At first I tried the same bulb with 2700K and I had the same results as the posted comparison - way too little contrast.
I have calibrated my RH Designs Analyser Pro for this bulb and, compared to the default settings from the device, it is 1 full stop brighter than the tungsten equivalent. It also has a little more contrast, but nothing too dramatic (I actually like it like this!)

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thank you for sharing your experience! This bulb is the same that i tried (i bought in "Obi" shop too), but there was some less contrast in the bottom of paper (it was a bit, but it was!). When i have time i want watch the lamp with welder mask for understand the diffusion of light and maybe i'll try again and check if i can improve the orientation.
If i undersand, your enlarger have reflex system for the lamp, so maybe this can help for have better result.

For my enlarger, i have the comfortable way that i need to put the light in a hole, so, it can work with some led panel with good light spectrum.

Hi,
In the end, after a lot of search for a led bulb that can replace the original lamp, i didn't found something normal or reliable.
So i decided to change my light system of the enlarger box, for make the light from up to down.
I took a plate, i cutted it with shissors for metal and i made the correct size for my box. After i made on it an hole calibrated in the center of the condensator.
I bought an osram lamp (the same specific of the thread's lamp) and i opened with a cutter (in youtube there are tutorials for open without damage it"). I removed the light diffuser and i siliconed it in the hole, i made longer the calbes inside the bayonet, for an easy connect, and i fixed with screw the led's plate upper the light's diffuser.
I also made the plate black with some paint for avoid reflections

So in the end, i have a plate with light, connected to the bayonet.
the enlarger are unmodified and if the light it will be broken, i can easy change the leds (i need only to open another lamp and take from it only the led's plate, make longer the cables and screw it!!)

I show all with image.
Of course is ugly and fast work, made with materials that i had at home, but it works!
I also had better result from the old lamp (little bit more density in the corner)

A lot of space inside if i move the lamphouse

Plate with holes and the bulb siliconed

Otherside of the plate

Led's plate with some metal connector and connected to bayonet

Other side of led plate

Led's plate assembled

new "lamp" mounted on the enlarger!

Lamp powered on

All closed you can't see nothing!

Light projected (reflection on column are due to the door opened )

I need to make more print, bit i think i can work with this system

Well done! Thank you for keeping us updated with details of your project. I would be especially grateful for a follow up about how your DIY led light source works in practice.

Hi, thank you!! I didn't create something new or special, in the end i only splitted the lamp in two parts!

In this image, you can see how my light box works

Finding some light similar to the old (the same power, the same uniformity, the same light spectrum, the same/similar size, made by full glass) is very difficut. Also if you found, you need to hope that the other specifics are good (short delay from power on and from power off, good quality of led, etc etc).

In the previous image, you can understand that the hole where light must go is in the bottom of box, so the light that go upper is unused (yes of course light is catched/reflected by the cover of the box, but in any case you don't really need this side of lamp)
The Osram lamp that we are discussing, is not full glass, and normally you must use with system like this:

If you put in my enlarger "as is", you can have light, but it can't be uniform (because the lamp house is horizontally and the light comes only from a little part).

If you watch this image from wikpedia, you can understand the parts of the led bulb (is not the osram lamp):

so in the end, i estracted the driver and the leds (in the osram they are one peace and not splitted like the image) and i put in one plate for make light in one way only (from top to bottom)

In the previous days i made some other prints, and i'm satisfied for the result! Also with different contrasts and other comparison from the thungsten light!

I hope i really found the definitive light system for my enlarger!


Marco

I've just picked up this thread after a long absence. A few years ago I posted this:
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Marco's post above looks promising.

LouisGR said:

I've just picked up this thread after a long absence. A few years ago I posted this:
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"Colour temperature is important with multigrade B&W printing.

My kit is a Focomat 1c and the Heiland Splitgrade system in manual mode with Agfa Gr 0 and 5 filters. I changed from Philips Photocrescenta 75W type PF 603 E51-P3/3 (phew!) incandescent lamps to a LED about 18 months back. I chose a 10W OSRAM warm-white LED lamp. According to the manufacturer, the colour temperature is 2700 degrees K, and the 10 W LED is equivalent to 60 W incandescent. The colour temperature of the Philips lamp is 2800 degrees K. The OSRAM bulb is virtually the same size and shape as the Philips and fits well.

My first prints were well-exposed, but the grading was too soft. After a round of trial and error calibration I have settled on giving 1.8 to 2 stops extra exposure with the Gr 5 filter, leaving the Gr 0 filter timing unchanged from the Heiland module reading [you can simply dial this into the module in steps of a tenth of an f stops].

This works very well and produces very nice prints. And the enlarger stays cool.​

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Marco's post above looks promising.

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Hi!
For now, the system work well.
Simeone more expert than me, sayed that it's impossibile that, with this lamp, contrast 5 can work, cause the multigrade paper need some light spectrum that led light can't provide (only the infrared led). So normally you Need to Build a light with mix of led, infrared led and some filter for make calibration of the spectrum.

I didn't had time for test the result with 5 grade.
In the worst case i Will use the OLD lamp only for this grade

marcolo88 said:

Hi!
For now, the system work well.
Simeone more expert than me, sayed that it's impossibile that, with this lamp, contrast 5 can work, cause the multigrade paper need some light spectrum that led light can't provide (only the infrared led). So normally you Need to Build a light with mix of led, infrared led and some filter for make calibration of the spectrum.

I didn't had time for test the result with 5 grade.
In the worst case i Will use the OLD lamp only for this grade

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Thanks for your work on this.
I think, however, that the LED that you would need to add to approach grade 5 would not be an infra-red LED, because that would be at the wrong end of the visible spectrum.
Grade 5 sensitive emulsions are sensitive to blue light, so the additional LED would need to be a blue light or blue + UV light.

MattKing said:

Thanks for your work on this.
I think, however, that the LED that you would need to add to approach grade 5 would not be an infra-red LED, because that would be at the wrong end of the visible spectrum.
Grade 5 sensitive emulsions are sensitive to blue light, so the additional LED would need to be a blue light or blue + UV light.

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Sorry i made mistake, i want say ultra violet led
How was your result with grade 5? Accettable?

I've switched back to EFP halogen bulbs for now.
The LED substitute available to me didn't put out enough light - exposure times were too long.
The contrast behavior with the LED bulbs I tried was significantly different from the halogen, but I decided not to work further toward "calibrating" them due to the light output issue.
My LPL 7700 enlargers do work normally with relatively low light output, so other enlargers may be more suitable for the not so bright LED bulbs.
And of course, there are new LED bulbs coming out every day.
I wanted the LED bulbs I had to work, because they ran very cool.

MattKing said:

I've switched back to EFP halogen bulbs for now.
The LED substitute available to me didn't put out enough light - exposure times were too long.
The contrast behavior with the LED bulbs I tried was significantly different from the halogen, but I decided not to work further toward "calibrating" them due to the light output issue.
My LPL 7700 enlargers do work normally with relatively low light output, so other enlargers may be more suitable for the not so bright LED bulbs.
And of course, there are new LED bulbs coming out every day.
I wanted the LED bulbs I had to work, because they ran very cool.

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Do you Need 250watt old lamp?
My led bulb cover perfectly the old 150 watt thungsten light!

I have an old 5x7 enlarger with a lightbulb the size of a soccer ball. The guy I got it from said it was in there when he got it in the 1950s. I have no idea what kind of messing around would be necessary once that thing blows....

marcolo88 said:

Do you Need 250watt old lamp?
My led bulb cover perfectly the old 150 watt thungsten light!

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No, but thankyou.
I was experimenting with an LED based direct substitute for an EFP bulb - one like this:
https://www.amazon.ca/Philips-314880-100W-Projector-Light/dp/B000N5MVAO

Here we are two years later. I mainly work with real colorheads taking real halogen bulbs. But I certainly have enough experience with LED substitutes to state that anything of that variety you buy in an ordinary store has an enormous BS coefficient built into its marketing labeling. In other words, if the package claims the bulb will last 7 years, factor a 20X BS coefficient, meaning you're lucky if the bulb lasts 3 months. And expect awful color characteristics. Their comparative lumen weakness has already been noted. But there are plenty of trash halogens out there too, including Phillips brand.

I encourage folks to build their own LED lamphouse like this one: https://www.photrio.com/forum/threads/led-split-printing-enlarger-lamphouse.173834/
I made a clone of that one for my Beseler 45, and it works well. Its grade 00 and grade 5 are identical to using Ilford's filters with a tungsten lamp, split-grade is easy by turning off green or blue, and the diffuser hides dust and scratches. You don't get these advantages when using a bulb from a store.