Philips Photocrescenta substitute

[AgX]

Concerning incandescent lamps, there are still at least 3 manufacturers in western Europe making low volumes of special models.

 

[snusmumriken]

Ah, that's a sad tale. I assumed you meant (earlier) that Photocrescenta bulbs were made in Germany under a Philips factory, or under licence to Philips. Much credit to whatever German business took on the production, but depressing about Philips' changing direction. I can understand that analogue photographers have become a tiny market, but light bulbs as a whole...? I shall look differently at my toothbrush this evening.

 

[AgX]

The german manufacturer is given at post #3. Sorry for not naming it myself. But there is nothing to licence today except for the Philips tradename of those lamps. But these lamps were made by several manufacturers in the past under their diffeent brands and tradenames anyway. And I in textbooks etc. that name was not even used, in contrast to the overrated studio lamps.
The technology of these enlarger bulbs was not different from making plain household bulbs, except for the diffusion coating, but such was used at some household bulbs too. So nothing Philips actually could shine with. I rather meant all the technology this manufacture had brought up in spite of "only" having started with light bulbs. Philips was lang time famous for their basic reasearch they did.

 

[snusmumriken]

The german manufacturer is given at post #3 ... these lamps were made by several manufacturers in the past under their diffeent brands and tradenames anyway. ... The technology of these enlarger bulbs was not different from making plain household bulbs, except for the diffusion coating, but such was used at some household bulbs too.

I misunderstood that too, my apologies. The Doctor Fischer bulbs that halfaman linked to are the ones to go for, then? Besides those, Fotoimpex also have genuine Philips bulbs 'for Beseler enlargers' at 5x the price, and not necessarily unused!

 

[AgX]

Basically there are various bulb shapes and american and european vary. Maybe this is behind that Beseler bulb, I did not look into this.

But for a european enlarger the Fischer bulbs are the ones to go for.

 

[snusmumriken]

Basically there are various bulb shapes and american and european vary. Maybe this is behind that Beseler bulb, I did not look into this.

But for a european enlarger the Fischer bulbs are the ones to go for.

Many thanks.

 

[AgX]

And socket threads vary too between USA and Europe !

 

[snusmumriken]

Fortunately I use a Philips enlarger!

 

[Ron789]

Regular household LED bulbs - 4000k or higher - work perfectly fine and have many advantages: easy to purchase, cheap, minimal heat, very bright (= short exposure times for large prints), long lifetime. I've used LED bulbs in my Leitz Focomat 1c and 2c enlargers, Durst 138s and SM183, all with perfect results at all grades, including split-grade printing with grades 0 and 5 filters.

 

[AgX]

A recent discussion on household LED bulbs replacing incandescent ones:

https://www.photrio.com/forum/threads/the-most-ideal-enlarger-light-bulb-for-some.166098/

 

[snusmumriken]

A recent discussion on household LED bulbs replacing incandescent ones:
https://www.photrio.com/forum/threads/the-most-ideal-enlarger-light-bulb-for-some.166098/

Thanks, I have been reading several threads here and elsewhere about LED lights. I definitely should make the experiment.

Regular household LED bulbs - 4000k or higher - work perfectly fine and have many advantages: easy to purchase, cheap, minimal heat, very bright (= short exposure times for large prints), long lifetime. I've used LED bulbs in my Leitz Focomat 1c and 2c enlargers, Durst 138s and SM183, all with perfect results at all grades, including split-grade printing with grades 0 and 5 filters.

Do you make test strips? I would expect a start-up time that might approach 0.5 sec to be significant when strips are made in increments of 2 sec (which is typical for me). Even with tungsten lamps, an exposure of 20 sec produces a print that is visibly different from one made with 20 x 2 sec exposures. This effect is said to be a property of the paper emulsion rather than the lamp. So any startup delay in the lamp would presumably add to it. Of course I could test this for myself very cheaply, but if you have already done it ...

 

[koraks]

This effect is said to be a property of the paper emulsion rather than the lamp.

It isn't. There's nothing in a paper emulsion that makes it respond this slow.

If the LED bulbs work (well) depends on their startup and shut down characteristics. Most LED bulbs are more or less instant-on, so that's not a concern; they tend to turn on quicker than incandescents in any case. The shutoff characteristics are more challenging; some LED bulbs employ slow phosphors or a power supply topology that makes them fade out instead of shut off instantly. You can visually determine whether this is true for any given bulb.

So in short, switch on behavior is not the problem; not for the lamp, and not for the paper. Turn off behavior is what you need to take into account.

 

[snusmumriken]

It isn't. There's nothing in a paper emulsion that makes it respond this slow.

Thanks for the correction. My mistake in comprehension. It's no excuse, but when I saw the word 'latency' my brain automatically thought 'emulsion'.

 

[Ron789]

Thanks, I have been reading several threads here and elsewhere about LED lights. I definitely should make the experiment.


Do you make test strips? I would expect a start-up time that might approach 0.5 sec to be significant when strips are made in increments of 2 sec (which is typical for me). Even with tungsten lamps, an exposure of 20 sec produces a print that is visibly different from one made with 20 x 2 sec exposures. This effect is said to be a property of the paper emulsion rather than the lamp. So any startup delay in the lamp would presumably add to it. Of course I could test this for myself very cheaply, but if you have already done it ...

Modern LED bulbs have extremely short start-up times. I sometimes make test strips, but most of the time I use a Kodak print scale, with 1 minute exposure, or light metering systems, or a single small test exposure, with an estimated time based on experience. Making a test strip with 20 2sec exposures seems odd and cumbersome to me. Test strips are best made using increments like F/stops, e.g. 4s, 8s, 16s, 32s, or, more precise with half stops, 4s, 5.6s, 8s, 11s, 16s, 22s, 32s etc.

 

[snusmumriken]

Making a test strip with 20 2sec exposures seems odd and cumbersome to me. Test strips are best made using increments like F/stops, e.g. 4s, 8s, 16s, 32s, or, more precise with half stops, 4s, 5.6s, 8s, 11s, 16s, 22s, 32s etc.

Well, this is probably not the place to defend my quirky practice on the grounds that I have been doing it this way for a long time! Unless I have screwed up badly, my negatives tend to need about 18-20 sec for a 16x12 print. I find 2 second steps around 18 seconds produces clearly visible differences. Even half stops would be a lot coarser that that. Of course I don't start exposing the paper at 2 sec, but it is practical to leave my (clockwork!) timer set to 2 sec while I'm doing test strips. Please let's not go off on a false trail here, though.

 

[bernard_L]

Thanks, that is fun. I had expected to see a spectrum like that in the phone app, with each MG filter narrowing it down to a different band. I wonder what the app is doing then?

The app is faking it. The camera has only three broadband detectors (times many pixels) for RGB. So I'm 99% sure the app is faking it, unless the phone has a spectrophotometer.
Suggested experiment: show your iphone app a CFL or a "neutral white" LED

and see what it tell you.

Moreover, the spectrum of light on the easel when using a MG filter actually consists of two distinct (esp. for hard grades) peaks: one, a balance of blue and green, for the paper, and the other, red, so that you have something to see on the easel when the ref filter under the ens is engaged. his cannot possibly be described as a single peak.

 

[koraks]

So I'm 99% sure the app is faking it, unless the phone has a spectrophotometer.

Yep. Well, granted, it's very well possible most smartphones actually use a separate/dedicated color temperature sensor, but the low-end sensors you'll find in a typical phone would also be 3-channel sensors, so the argument still stands...

 

[snusmumriken]

Looks like you are absolutely right. This is what it showed me with a neutral white LED bulb. I had to point the phone slightly away from the light to make the blue peak appear at all, and that may reflect our blue kitchen cabinets!