Alternative Enlarger lamps

Hello forum,

 

I'll shortly be making my first attempts at darkroom printing. I have a Leitz Focomat 1a with a Schneider Componon-S 50mm f/2.8. Both are in great condition. The lens seems too compact for the auto focus to work on the Focomat and I believe I'll need an extension tube to fix that. Will look into that in the future, for the moment though I'm still able to focus with smaller paper sizes (on larger magnifications I have to adjust the lens focus mechanism dangerously close to the end of its thread).

 

The enlarger requires a 75W opal lamp. This city has power of 220V, however I've only been able to find enlargement lamps in the national market for 110V (the older big cities use 110V in Brazil). I could get a transformer, but since the lamps are rather expensive (and perhaps aren't even real enlarger lamps), I'd like to try some alternatives. I won't import from abroad because of the cost and having recently not received a couple of international items posted to me.

 

I have read that opal finished LEDs with a colour temperature of 4000K produce good results. I have not been able to find one with the equivalence of 75W incandescent. I have however purchased the following lamps, none of which have any writing on the lamp itself.

 

a) an opal LED with colour temp of 4000K and wattage of 7W (== 50W incandescent).

 

b) a compact fluorescent with colour temp of 4100K and wattage of 14W (== 70W incandescent).

 

c) an Osram "silica" incandescent lamp of 40W ("opal" finished but not actually so-called)

 

Both lamp a and b switch on and off very responsively. Lamp b is of course the brightest and the easiest to focus with. All 3 produce a similar looking light.

 

Can anyone please give an opinion on these options? If I use the LED of 50W will I just need to adjust my exposure times by a factor of 1.5? (ie. 75/50 = 1.5)

 

I'm inclined to use the 50W LED as it has a more "classic" form factor. The florescent is more elongated and extends fairly close to the condenser - and i think may produce a less even spread of light (although to my eye, it looks the projection looks nice and even).

 

Thanks - all the best!

Use the LED lamp. The CFL will take an age to reach a stable brightness.

 

I'm able to walk into any discount store and buy an LED bulb with opal plastic cover with any (equivalent) wattage from 60 to 150. I think you just need to look a bit harder.

 

In any case, the difference in light output between 50 and 75 watts isn't that great.

 

Modern papers are quite a bit faster than when that old Focomat was built, so you might even benefit from using a lower output bulb, in that exposure times will be more controllable, especially on smaller prints.

 

Try to get hold of the instructions for the Focomat. There are two mechanisms controlling lens extension - the manual helix and the autofocus parallelogram. They both need to be adjusted properly, and it sounds as if they aren't.

 

I believe the Focomat was often supplied with a Leitz Focotar lens. This lens has quite a long body, so you may well need a short extension tube for small prints. Old Leica-fit extension tubes should be easily and cheaply obtainable if the parallelogram adjustment isn't sufficient.

Edited December 8, 2018 by rodeo_joe|1

Thanks. Actually I looked pretty hard and went to a square with probably 40 lighting shops. :) lots of options at 3000k and at 6000k but few at 4000, which I believe is neutral. Yes, I have the manual. It just won't adjust as described because the lens is too short. I saw elsewhere someone recommending an extension with the schneider

For black and white enlarging 3000k should be fine--the original bulb would have been around that color temperature, and going too high on the kelvin scale will just necessitate adding more yellow filtration with variable contrast paper to get normal contrast. When I used a cold light head (fluorescent tube somewhere around 5400k) I needed a 40 CC yellow filter to bing contrast back to normal so that VC filters gave appropriate grades of contrast. Rodeo Joe is correct that newer papers are more sensitive than older ones used to be so the 50 watt equivalent may well be your optimal choice. I would also avoid CFL bulbs--they take a little while to get up to full output and age badly, as well as frequently having incomplete color spectra, which can also lead to troubles with variable contrast papers.

So in your opinions, LEDs are OK?

I suspect LEDs will cause lots of problems for color printing, but could be fine for black and white.

 

I remember being told when I was younger (I got my first enlarger when I was about 10) that enlarger lamps didn't have the label on the end with the company name and wattage, like ordinary lamps have. That would be in just the right position to get in to the image, though somewhat blurred out.

 

I don't know that the usual LED bulbs have the right light distribution, along with the condenser lenses, to uniformly illuminate the negative, but if they do, they should work well enough for black and white.

 

As mentioned, they might complicate variable contrast filtering.

 

The usual white LEDs are made from a blue (almost violet) LED, plus a phosphor coating to generate (like fluorescent lamps) red and green.

That could have a not so obvious effect on VC paper. Best would be to use them with graded paper.

 

You can also use a big diode, commonly sold as high wattage voltage converters (they work well for heating appliances) to convert to 120V.

(Unless your enlarger has a fan. I don't know of any that do, but I suspect some might.)

 

I suspect that if both 230V and 115V appliances are common, then transformers are easy to find.

At 75W, the transformer isn't so huge, but still not cheap.

B&H in NYC appears to have a pretty extensive selection of enlarger bulbs. If available, it is probably worth the trouble and cost of ordering the proper bulb for the enlarger if they stock it.

So in your opinions, LEDs are OK?

The LED might work well enough and can't be that expensive so I would give that a try. With some regular bulbs the label will show on your prints --I had that happen to me once when I had an enlarger bulb burn out late at night and had to replace it with a regular bulb. The amount of diffusion with a stock LED bulb might not be enough to evenly distribute the light over the condensers--you can test for that by exposing a sheet of paper for a short time with no negative in the carrier. If the light is even over the whole negative then the print should come out a uniform shade of gray. If the corners are lighter then the light output isn't even and you may need a different bulb or to check the condenser lenses to make sure that they are positioned and aligned properly.

Thanks for the information Glen. Good idea about the test, AJG, i'll do this, and Sandy, yes, i will try to get the real thing at some point.

 

I had some success printing this afternoon. I used a 1+7 dilution of Adox Adotol NE, a 2% stop solution that i mixed from 4% acid vinegar and standard Kodak fixer. The paper size is 3.5 x 5 inch so after doing some tests strips I settled on just 2 seconds at f/8 (using the ~50watt LED). I developed for a minute agitating the tray every 10 seconds. Stopped for 10 seconds, agitating more or less constantly and fixed for 2 minutes agitating every 10 seconds. Please let me know if I'm doing anything wrong with this.

 

I settled on f/8 (i also tried f/16 which didn't seem much different) because I read somewhere that smaller apertures can give less contrast. Is that correct?

 

The paper i have is Ilford Multigrade IV. I don't yet have any filters to play around with contrast, but that's something I'll try in the near future.

 

Here is a shot of our washing line and the first photo, taken with my phone (the focus is good in the print). But, a question: I've had real trouble framing because I cant see very well with the safe light I'm using. The light looks purpose built and has a heavy red filter at the front of a closed cylinder. For the element I've used a 40watt red incandescent lamp - i wonder though if i can use a standard 40watt bulb however? - it might make it easier to see.

 

All the best!

 

here is the safe light:

 

The spectrum of a white LED is much more even than most fluorescent tubes. It's a little lacking in the cyan region, and heavy in the blue-violet region, but overall reasonably well-balanced. I see no reason why one wouldn't work perfectly well with VC paper; maybe with a slight adjustment to the recommended filtration, but certainly a lot better than a CFL tube.

 

Most of the domestic LED bulbs I've seen have no lettering on the opalised plastic enclosure, so no issue there either.

 

Here's a comparison I did some time ago between 'daylight' LED lighting and actual sunlight.

 

A safelight like that should have a 15 watt bulb fitted, or no more than 25 watts at most. A dark red filter isn't needed for B&W printing, it should be fitted with an amber filter. Anyway, don't expect to be able to see well enough to read in darkroom lighting. It should be dim.

Edited December 8, 2018 by rodeo_joe|1

Cool White LED bulbs: Are they "full-spectrum"?

 

has spectra for cool white and warm white LEDs.

 

I don't know so well the spectral sensitivity of VC paper.

Hopefully the OP can tell from his prints if the contrast is off one way or the other.

By framing I assume that you're meaning positioning the paper under the enlarger? Do you have an enlarging easel? If you do this shouldn't be that hard to do--open your enlarging lens up to f/2.8 to position the easel and focus, then stop down to f/8 to print. If you don't, get one when you can. By the way, there should be a visible difference between 2 prints exposed for the same time interval (2 sec.) and different f/stops. f/16 should only allow only 1/4 as much light to reach the paper as f/8, and unless both prints are totally over exposed (completely black) the f/16 print should be much lighter. You might want to take the lens off of the enlarger and look at the diaphragm to make sure it is working properly.

Cool White LED bulbs: Are they "full-spectrum"?

 

has spectra for cool white and warm white LEDs.

 

- Where? I don't see any spectra there at all.

 

In any case, I went straight to the horse's mouth and examined a few LED spectra through a slit+prism spectroscope. As described above, the spectra were pretty even and not spikey. The only deficiency was in a small band between blue and green, but VC papers are only interested in the green and blue output.

 

I would post the spectra, but it's actually impossible to capture the LED (or any continuous) spectrum with a digital camera, since the Bayer filters are cut too narrowly to show anything but three separated RGB bands. And people worry about the quality of photographic lighting!

By framing I assume that you're meaning positioning the paper under the enlarger? Do you have an enlarging easel?

 

Yes and yes. And yes, I realise i wasn't using it properly! Thanks, I think I have it sorted out now.

 

By the way, there should be a visible difference between 2 prints exposed for the same time interval (2 sec.) and different f/stops.

 

Yes, the f/16 print was made with a longer time interval. What I was wanting to know is, when the time interval/exposure is adjusted correctly for each aperture, should there be any qualitative difference between an enlargement made at f/8 and f/16? For example, will there be a difference in contrast? Some of the blogs I read recommend using f/16 for enlargements and others recommend f/8. I can see that f/16 gives more room for fine tuning when setting the exposure time, however I read somewhere else that contrast may be reduced at small apertures, which is why I chose f/8 - and also because, to my knowledge, lenses tend to perform best in terms of sharpness, at least when taking photos, at f/5.6 or f/8. It depends on the particular lens, of course.

 

A safelight like that should have a 15 watt bulb fitted, or no more than 25 watts at most. A dark red filter isn't needed for B&W printing, it should be fitted with an amber filter. Anyway, don't expect to be able to see well enough to read in darkroom lighting. It should be dim.

 

Can that 15-25 watt bulb be "white"? Perhaps my 40 watt red bulb has an equivalent brightness. I checked the filter again and it's definitely red and not amber. Do I take it that red is an overkill with B&W? In any case, now that I've worked out how to use the easel properly, I'll have less problems.

Yes and yes. And yes, I realise i wasn't using it properly! Thanks, I think I have it sorted out now.

 

 

 

Yes, the f/16 print was made with a longer time interval. What I was wanting to know is, when the time interval/exposure is adjusted correctly for each aperture, should there be any qualitative difference between an enlargement made at f/8 and f/16? For example, will there be a difference in contrast? Some of the blogs I read recommend using f/16 for enlargements and others recommend f/8. I can see that f/16 gives more room for fine tuning when setting the exposure time, however I read somewhere else that contrast may be reduced at small apertures, which is why I chose f/8 - and also because, to my knowledge, lenses tend to perform best in terms of sharpness, at least when taking photos, at f/5.6 or f/8. It depends on the particular lens, of course.

 

(snip)

 

For film, it is usual that pushing, decreasing exposure and increasing development, increases contrast.

 

I have never known that used for printing.

 

For printing, development goes close to completion.

Small differences in development time don't change the result so much.

Over or underexposed prints usually can't corrected with changing development.

 

Most papers have a recommended 60s or 90s time in the appropriate developer.

If you expose appropriately for the recommended time, you won't find much difference between

equivalent exposure at different f/stops.

 

Many enlarging papers now are fast enough, that you almost have to go to f/16

to get reasonable times. With many timers, it is hard to get less than 10s or so.

 

For camera lenses, diffraction limits sharpness at small apertures.

By symmetry, that should also be true for printing.

 

For printing, there is only one distance to the paper. There is no

need for depth of field to allow for differing object distance.

Some depth of field helps with focus accuracy.

 

Without actually doing the diffraction calculation, I have never

worried about using f/16. I suppose with some neutral density,

you could get a reasonable time at f/8.

 

(snip)

 

Can that 15-25 watt bulb be "white"? Perhaps my 40 watt red bulb has an equivalent brightness. I checked the filter again and it's definitely red and not amber. Do I take it that red is an overkill with B&W? In any case, now that I've worked out how to use the easel properly, I'll have less problems.

 

Most safelights use a white (or clear) bulb and specific (usually) glass filter.

 

Some use a colored bulb, such as red, without a separate filter.

This is more usual for starter kits.

 

You would not use a colored bulb and also an added filter.

 

Popular enlarging papers use the 0C safelight filter, which is bright enough

to work pretty well in a darkroom. You should be able to read (data sheets

or timer numbers) under a 0C safelight.

 

Panalure and some color papers use a #13 filter, which is very dark.

I once dropped some paper on the floor, and couldn't find it under a #13

safelight. The #10 is even darker.

Can that 15-25 watt bulb be "white"?

 

- Definitely. Safelights like that were designed to take an ordinary 'pigmy' tungsten bulb of the sort you find in a fridge light.

 

Your safelight looks as if it was designed to take interchangeable filters - probably the same as the filters for the old Kodak 'Beehive' safelight. My Kodak Beehive came with half a dozen different filters, which wouldn't work if it was fitted with a red bulb.

 

Glen. A line on the CIE 1931 horseshoe is not a spectrum, and neither are some vaguely drawn and outdated curves.

Edited December 9, 2018 by rodeo_joe|1

The diagram here shows a much better comparison between LED, CFL and Tungsten outputs.

 

As can be seen, a conventional incandescent bulb has a very poor output at the blue end of the spectrum, where photographic paper is most sensitive. Therefore, substituting a lower wattage LED lamp for a tungsten-filament bulb seems entirely appropriate.

 

The previously noted dip in the cyan region of the LED spectrum still emits more energy in that region than a conventional incandescent lamp. Almost half of a filament lamp's energy is wasted in the invisible infrared region.

Yes and yes. And yes, I realise i wasn't using it properly! Thanks, I think I have it sorted out now.

 

 

 

Yes, the f/16 print was made with a longer time interval. What I was wanting to know is, when the time interval/exposure is adjusted correctly for each aperture, should there be any qualitative difference between an enlargement made at f/8 and f/16? For example, will there be a difference in contrast? Some of the blogs I read recommend using f/16 for enlargements and others recommend f/8. I can see that f/16 gives more room for fine tuning when setting the exposure time, however I read somewhere else that contrast may be reduced at small apertures, which is why I chose f/8 - and also because, to my knowledge, lenses tend to perform best in terms of sharpness, at least when taking photos, at f/5.6 or f/8. It depends on the particular lens, of course.

 

 

 

Can that 15-25 watt bulb be "white"? Perhaps my 40 watt red bulb has an equivalent brightness. I checked the filter again and it's definitely red and not amber. Do I take it that red is an overkill with B&W? In any case, now that I've worked out how to use the easel properly, I'll have less problems.

I did some practical testing with my set of El Nikkor enlarging lenses a long time ago and standardized on f/8 for 50 mm f/2.8,f/11 for 80 mm f/5.6 and 105 mm f/5.6 and f/16 for 150 mm f/5.6. These were the optimal apertures for my particular set of lenses and Zone VI enlarger that they are used on. I doubt that you will see a significant difference in contrast with a smaller f/stop but you may begin to see a slight loss of sharpness due to diffraction with large prints

The catch is that the lamp mountings may be varied, so you may need to replace both the bulb and the socket (or the whole head even). In fact the latter is probably the way to go. Edited December 11, 2018 by JDMvW

Many enlargers have lamps that use the usual lamp base, and adapters are

available for some lamp bases.

 

The Omega B22 that I have uses the 111A lamp with bayonet base:

 

SYLVANIA 11624 - PH/111A - 75 Watt - S11 - BA15s Base

 

It might not be easy to replace the socket, as it might be somewhat closely

part of the enlarger head.

 

The size and position of the bulb, in relation to the condenser lenses,

is an important part of the optical system.