[Jean Poitiers]

Hi all,

Just a quick question here to ask for some more knowledgeable input and/or experience.

A long while back at my thrift store I picked up an almost new-in-box Polish "Krokus 3 (Color)" enlarger with a working bulb. I got it to print some negatives from my Pentax 6x7 (instead of scanning) ... and now I have a Fujica G690 BL, so I really would like to go forward to this print project.

That bulb was a 150W which is the max for the enlarger without its extension tube and it just died. What are my other possible options aside from buying a similar bulb as a replacement? For a test, I put in an old IKEA 11W fluorescent type bulb and it did not look too bad with the test negative I had in the Krokus.

What could anyone suggest and thanks in advance for your input. Cheers, J

[stevebrot]

Online photos show an enlarger with a filter drawer. Assuming that the bulb had a tungsten filament, I would attempt to replace like with like, even if doing only B&W work. Halogen would be a second-best choice with CF or LED being distant 3rd and 4th. My concern would be emittance spectrum, particular if you are interested in using VC papers or dipping into color.


Steve

[UncleVanya]

Home | Freestyle Photographic Supplies

Also search for any enlarging bulb on Amazon for example this: PF603E 241V 75W E27

Wattage differences only will cause longer exposure times.

[sqrrl]

I'd really be looking for an enlarger bulb, my krokus 66 had a regular base (I think shape excepted they're the same thing), so it shouldn't be too hard to find a bulb with that base. You can go for a lower wattage bulb with the results that it will take longer to expose a photo. The 150w maximum is related to heat buildup, more light equals faster printing, which isn't always a good thing.

CFL is probably your worst choice as the colour spectrum isn't great, and it takes time to get to full brightness as it warms up, which means your repeatability in a series of long exposures will go all to hell. LED has the same problems with colour spectra, but at least it's instant on at full power unlike the CFL.

The best for your purposes is tungsten, and you really want an enlarger bulbs they are opaque white (which avoids hot spots) and don't have the label printed on the end of the bulb (most commercial bulbs do this).

[stevebrot]

CFL is probably your worst choice as the colour spectrum isn't great, and it takes time to get to full brightness as it warms up, which means your repeatability in a series of long exposures will go all to hell.

In addition, many continue to glow even when turned off (lesson learned hard way while loading a daylight tank).


Steve

[ChrisPlatt]

In addition, many continue to glow even when turned off (lesson learned hard way while loading a daylight tank).

When I built my first darkroom I installed a 2 x 40 W fluorescent shop light fixture for ambient lighting.
To my surprise those long tubes would continue to glow for several minutes after being turned off.
I never replaced that fixture so I had to be careful to wait awhile before opening any boxes of photo paper.

Replacing the enlarger lamp with the original type incandescent is probably your best bet.

Chris

[Not a Number]

The old bulb should have a manufacturer and model designation stamped on it. A simple search engine query should turn up a source for replacements. Back when 8mm projectors went the way of vinyl record players (80s-90s) I bought as many spare lamps as I could find in the local stores but it turns out a few companies are still making the lamps today.

[WPRESTO]

I would advise at least looking for a supplier of bulbs. I have come across some that list an astonishingly variety of otherwise hard-to-find-&-get bulbs. Whether necessary or not, there were bulbs specially made for enlargers. B&H, Adorama and Freestylephoto all list multiple bulbs specifically intended for use in making prints.

You could also go to a more general supplier such as bulbs.com or lightbulbs.com, but I think they are less likely to have photo-enlarger bulbs.

[Bob 256]

I would try this lamp if it is anywhere similar to the old style. It has a CRI of over 80 and should give comparable results to an incandescent (these LED lamps use a phosphor to emit their light and it is almost a perfect continuous spectrum match but for the pump wavelength near the UV end). Go for the 2700K version since that comes closest to what you probably had. You won't ever have to replace it again with the lifespan of LEDs. No guarantees that the color will match your old lamp but you will use color gels anyway to balance color and I would guess it will be really close without that.

https://www.alliedelec.com/product/sylvania/79292/71075876/?gclsrc=aw.ds

[stevebrot]

It has a CRI of over 80 and should give comparable results to an incandescent (these LED lamps use a phosphor to emit their light and it is almost a perfect continuous spectrum match...

Spectral sensitivity of B&W photographic papers varies by contrast grade with the general assumption that the light source is ~3000K emission spectrum, a close match to most enlarger lamps*. This is not the same as perceptual equivalence (CRI) to 2900K as deficiency or peak may affect both paper speed and contrast grade.


Steve

* A quick survey of the selection at B&H shows lamp color temps from 2850K to 3400K.

[Not a Number]

Variable or poly contrast papers are sensitized for green light. Varying the color spectra varies the contrast. The set of poly contrast filters I own have a magenta to yellow cast.

[fs999]

I have found three online vendors in France : Caddy Photo, ProPhoto and MX2

[stevebrot]

I have found three online vendors in France : Caddy Photo, ProPhoto and MX2

Yay!!!


Steve

[Wheatfield]

I'd really be looking for an enlarger bulb, my krokus 66 had a regular base (I think shape excepted they're the same thing), so it shouldn't be too hard to find a bulb with that base. You can go for a lower wattage bulb with the results that it will take longer to expose a photo. The 150w maximum is related to heat buildup, more light equals faster printing, which isn't always a good thing.

CFL is probably your worst choice as the colour spectrum isn't great, and it takes time to get to full brightness as it warms up, which means your repeatability in a series of long exposures will go all to hell. LED has the same problems with colour spectra, but at least it's instant on at full power unlike the CFL.

The best for your purposes is tungsten, and you really want an enlarger bulbs they are opaque white (which avoids hot spots) and don't have the label printed on the end of the bulb (most commercial bulbs do this).

This last part is important. The label on the bulb will show up in prints. If you can’t find an actual tungsten enlarger bulb, I would suggest a warm white (3000k) led. Halogens get quite hot, hotter than an incandescent bulb. They aren’t well suited to equipment that wasn’t designed to use them.
LED bulbs run cool, and have heavy enough diffusers that hot spotting shouldn’t be a problem. The spectrum might be a bit off for VC papers, but it will probably just mean using a slightly different filter grade compared to the original lamp.

---------- Post added 04-25-19 at 09:54 PM ----------

I have found three online vendors in France : Caddy Photo, ProPhoto and MX2

Excellent.

[Baala]

Sorry to be little out of topic, but I'm new to this forum and I'm genuinely surprised that somebody outside of Poland is using a Krokus enlarger and even more surprised, that nobody is complaining about it ("buy something better!"), but giving good advice instead, it's very refreshing.