jim, I wonder if you have just re-invented the wheel. Your comprehensive reply is going to keep us informed. Thank you. - David Lyga
jim, I wonder if you have just re-invented the wheel. Your comprehensive reply is going to keep us informed. Thank you. - David LygaNo lamp is going to be perfect. Even the sun doesn't put out an even spectrum, yet it's the measuring stick by which all bulbs are compared to. But incandescents, like the sun, put out a near linear spectrum. Incandescents tend to be higher in the red and infrared, and don't put out much UV. LED's tend to have pretty jagged spectrums and can put out a lot of UV. Fluorescents are even worse in those regards. But printing papers and filters were designed with incandescent bulbs in mind, so they're as close to perfect as you'll find.
Like I said before, if you really want to get serious with LED bulbs, I would consider the Hue or Lifx lights as probably the way to go. They have the option to display over 16 million colors and over 1,000 shades of white. They use a combination of red, green, blue, and white LED's in their bulbs, so they shouldn't have any major dips in their spectrum that can't be tuned out. So it should be possible to find an appropriate color that will work with any setup, color or variable contrast B&W. They are also dimmable. The problems are that they are software controlled and pretty expensive, plus the Hue bulbs require a hub. I've never attempted to use one, so I have no idea how practical they are in use, nor how difficult it would be to tune it to work appropriately.
Ron, are you inferring that I cannot get adequate contrast differentiation with my 'low' 3000K bulb? I have tested but cannot see a contrast difference compared with my #211. Your '3000' seems to be a bit underexposed. - David LygaLED bulbs work perfect! Just make sure you have bulbs with a color temperature 4000K or higher. The image shows my test results. You can also look at this post:
https://www.photrio.com/forum/threads/using-led-bulbs-in-an-enlarger-great.148255/
View attachment 219335
http://www.modernenlargerlamps.com/Modern_Enlarger_Lamps/Model_2_Data.html
Here are the VC tests Emil performed with the Modern Enlarging Systems Model 2.
His enlarging head uses Cree XP-G LEDs which he says are the best you can get.
The lamps I used for these test are Osram Parathom Classic (4000K) and Philips (2700K); don't recall what the 3000K was. The incandescent was a Philips Photocrescenta 150W at 230 volts. And you're right: there are fluctuatiions. So there is no guarantee and I recommend you do your own testing. I have several Osram Parathom Classic 4000K bulbs in use, different watts, and they all work fine.The test that Ron presented is very interesting. But as he did not specifiy the models of lamp (and this includes the incandescant one and the voltage he is running it too), we only can guess that it all will work with the models we would use.
Moreover I got the impression that there still is fluctuation of models even at one manufacturer.
Hi to everyone! i'm Marco and i'm writing from Italy. I'm a analog printer too and i have a question about the replacement of tungsten bulb
I have a durst D659 enlarger that work with 150w opal lamp.
Unfortunately in Italy, the new lamp is only available from the brand Dr Fischer, but the liftime of that lamp is really short!
The test of @Ron789 is interesting and i'm courious how 4000 kelvin temperature can work correctly with the contrast of paper!
I have a question for Ron (or for who know it), wich lamp i can use for my enlarger ?
My lamp housing is not like yours, is horizontal upper the condensator:
So, if i use the osram parathom, i have a little problem of diffusion of light (expecially, very little, in the bottom right side). (i tried that lamp and i saw the result).
I tried also the osram opal lamp (full glass), but the result was not good (wrost diffusion of light).
There is some tested lamp that i can use for replace the 150 watt?
Thank you very much for the help
Shipping may be too high to the EU but see what FreeStyle has. https://www.freestylephoto.biz/
I have been using a led bulb in my Meopta Opemus 6 for 3 years now with no problems, I us a 2700 14.5 watt bulb, and I get all grades, nice prints, works fine, you do need the 2700 warm bulb, the cold tone bulb won't give the grades, easily as good as a tungsten bulb, but nice and cool, no negative popping, so no focus problems
Richard
TThanks, i saw they have tungsten light very cheaper, but noto led of course.
Thank you very much, before watching this thread, i tried a full opal led light (Philips) of 2700 kelvin and 17,5watt....but It wasn't enough for the print (very very very long time). Consider that my enlarger Need 150watt.
With 4000 kelvin i saw more food result but i agree that i Need 2700 kelvin for the same result.
Do you have some lamp model to suggest?
Thank you again
Yes, i asked because i tried different lights without success.From experience: With a condenser head, if the LED bulb is physically longer or shorter than the proper tungsten bulb, the result could be significant non-uniformity of illumination on the print due to the optics of the condenser.
As others have posted, test your LED bulb well.
Mark Overton
T
The bulb brand I use is an own brand bulb from a DIY store, B@Q, and is a dial brand, but I would the kelvim rating and wattage rating is pretty much the same though all brands
contrast grades (through filtering) are never 'excact' and don't have to be. It's better to adopt a procedure of: if print looks too soft use a higher grade filter or i it feels too hard use a softer grade filter rather than looking for 'exact' grades. printing is an art not a science.I think the bottom line here is that not all led bulbs are the same. In the facility where I teach darkroom, the owner replaced the lamps in all of the Beseler 23C enlargers with leds. Worked fine for my beginners, but I was skeptical when it was time to imtroduce contrast filters. However, they appear to work fine. Or, at least well enough for our purposes. I am still skeptical that the grades are exact, but if one can get the print they wish, the all is well. As was said, test and see.
PS: I won’t be switching the lamps in my own enlargers as long as oem lamps remain available. And I have about a ten year supply.
Hi to everyone! i'm Marco and i'm writing from Italy. I'm a analog printer too and i have a question about the replacement of tungsten bulb
I have a durst D659 enlarger that work with 150w opal lamp.
Unfortunately in Italy, the new lamp is only available from the brand Dr Fischer, but the liftime of that lamp is really short!
The test of @Ron789 is interesting and i'm courious how 4000 kelvin temperature can work correctly with the contrast of paper!
I have a question for Ron (or for who know it), wich lamp i can use for my enlarger ?
My lamp housing is not like yours, is horizontal upper the condensator:
So, if i use the osram parathom, i have a little problem of diffusion of light (expecially, very little, in the bottom right side). (i tried that lamp and i saw the result).
I tried also the osram opal lamp (full glass), but the result was not good (wrost diffusion of light).
There is some tested lamp that i can use for replace the 150 watt?
Thank you very much for the help
Hi Marco, looking at the picturesI of your enlarger, I fear the basic layout of the lamphouse (which puts the lamp in a horizontal position at an 90 degree angle relative to the condenser/light path) does not go well with LED bulbs in general. The reason is that, unlike incandescent bulbs, the peak of light output of common LED household bulbs is often concentrated in a zone perpendicular to the long axis of the bulb (and LED light is very directional to begin with). So only relatively little light is emitted to the "sides" of the bulbs, which is where your condenser system is located. I think this is why you do not get satisfactory results with the LED bulbs regarding light distribution and intensity. Now, there are LED bulbs which have a more even (wider angle) distribution of light (close do 300 degrees, IIRC). Some vendors publish diagrams which show the light distribution of the bulb. You could try to find a LED bulb which emits a lot of light to the sides (light distribution angle preferably ~ 300 degrees). But my guess is you will still loose a some brightness compared to an opal lamp. So, what can be done?
I am not familiar with the details of the lamphouse of your enlarger, but my first check would be if it is possible to alter the location of the socket within the lamphouse to bring it in a vertical position above the condensers. Looking at the pictures of the housing, there is probably not enough room at the top of the condenser.
Second possible solution would be to somehow install a mirror of appropriate size at an angle of 45 degrees above the condenser system (the lamphouse of the Durst L138 actually uses a very similar layout: The lamp is positioned to the side of the actual light path and uses a mirror to deflect the light in the direction of the condensers).
Third idea would be to install an LED panel of appropriate size right above the condenser system. So ... I cannot offer any plug and play solution for your problem. Good luck and keep us posted how your project goes ...
Hi Marco, Philips has recently introduced a new LED buld that has the same shape as traditional tungsten bulbs: https://www.123led.nl/Philips-E27-led-lamp-peer-mat-koel-wit-10-5W-100W-i4232-t573.html
I have not tried it yet but it might solve your problem of uneven light spread.
My experience with LED bulbs is they have a lag time when first lit, and an after-glow when extinguished.
I still have a question, maybe you can clear my mind. In this thread, Ron have the same result with cooler light (4000k), in the web, i saw people use 4000 kelvin too (sometimes much cool light). If i understand, the classic light of 150w have color temperature little bit less than 3000 kelvin, how is possible that this change doesn't impact with the color filtration for multigrade papers?
And if i need to make some led panel, is better if i use 4000 kelvin temperature or is better be to 2700 kelvin ? If is the second, why i have better results too with 4000 kelvin?
Maybe is only because 4000k led bulb have different spectrum's light that work better with condensator.. but i don't know!
Really thank you for your information. Unfortunately what tou said is correct. There isnt' a real led lamp that can emulate perfectly the old lamp.
For your suggestions:
1. I can change orientation of light, but i must find some e27 short lamp because i can't close the top of enlarger. So i think is impossibile
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