Which is it - orange or red?

Rolf-Werner · 2014-09-05T09:37:25+00:00

Gerade beim Stöbern entdeckt: Nach allem, was ich hier in den letzten Wochen zum Thema gelesen habe, sind hier die Texte vertauscht: € Orange-Filter: Ers...

Rolf-Werner

Just spotted whilst browsing: judging by everything I’ve read on the subject here over the last few weeks, the descriptions seem to have been swapped around: € Orange filter:

Replacement filter for the Kaiser darkroom lamp. Multigrade, for variable contrast papers and fixed-grade black-and-white papers. €

It says here: http://www.fotoimpex.de/shop/fotolabor/kaiser-dunkelkammerlampen-filter-orange-9x12-cm.html € € Red filter:

Red, for orthochromatic films and papers, lith and line materials, and black-and-white papers with fixed gradation. Replacement red filter for the Kaiser darkroom lamp. €

Available here: http://www.fotoimpex.de/shop/fotolabor/kaiser-dunkelkammerlampen-filter-rot-9x12-cm.html € So, which one is it then? :)? I reckon it must be red for variable contrast papers (especially Foma) and orange for fixed-gradation? € And while we’re on the subject, what’s your experience been with the Duka red lamp? http://www.fotoimpex.de/shop/fotolabor/dunkelkammerlampe-rot-ap.html € € Thanks for the clarification! € Rolf €

bernhardmangelsgmxde

Red for pretty much all papers with variable gradation, and actually for fixed-gradation papers too. Orange for most papers with variable gradation, with the exception of (most) Foma Variant papers.

ThomasPauly

ORANGE - ADOX and Ilford gradation converter papers € RED - Foma gradation converter papers - orthochromatic materials € Red is also suitable for fixed gradation; however, green is even better, as the eye is most sensitive to green and the Duka lighting is therefore perceived as brightest. € Best regards € tepe

AchimBauer

Good evening everyone, € About 38 years ago, my father suddenly went into the studio, fetched the enlarger he’d built himself a long time ago, and switched it on. I don’t know where the photographic paper came from, nor where the chemicals came from, but they may well have been leftovers. The Duka light was a red-painted light bulb, and it did the job. Once I’d got a taste for it, I upgraded to Ilford Multigrade (the only multigrade available at the time), because as a student I couldn’t afford to keep stock of paper for every gradient. And to go with the Multigrade, I had to have the Ilford SL 1 – orange and blindingly bright! After getting back into it, I fitted two more Kindermann units in my darkroom, because I had them without knowing where they came from, and a pile of different filters, but today, just as back then, I work with the SL1 and it has seen a lot: Agfa, Ilford, Tura, Labaphot, Tetenal, Tetenal Fotografickit, Orwo, Mimosa, Lenoar, Adox Easy Print, Adox MCC and Foma. OK, I’ve turned it towards the wall because it’s so bright and, after getting back into it, I was using unfamiliar materials, but in the old darkroom it was shining directly into the room – and that was a broom cupboard – but I never had any problems. € Regards, Achim

Rolf-Werner

Yeah, now I’m really a bit flummoxed! What I’d heard so far – including on other forums – was: red, red, red. And ideally, check it with the CD and do an exposure test. LEDs are supposed to be good, red ones of course… :) € All other colours are more or less discouraged, or at least come with a gentle warning. € And now I’m hearing here that orange is supposed to be good too, at least for everything except Foma (more or less). In any case, your observations fit the descriptions better than my ‘knowledge’. I mean, I’ve got nothing against red, I was just surprised by the descriptions in the shop, but according to what you’re saying, that seems to add to the picture. € This is an important topic for me because I’m in the process of setting up a new darkroom, and my old green-brown filters are only suitable for fixed gradation. € So can we conclude: red for everything, orange for almost everything? € But why the difference in the first place? € Rolf

TiMo

I use Orange for MCP. No problem. The AP lamp linked here is quite a bright red. Fomabrom fogged it for me. MCC and Variotone are no problem. For Fomabrom, I use this one: http://www.fotoimpex.de/shop/fotolabor/kaiser-dunkelkammerlampen-filter-rot-9x12-cm.html … But it gets so dark that it makes almost no difference compared to working without a lamp. If anyone has a recommendation, I’d be very grateful.

Rolf-Werner

Aren't there three of them, each with a different brightness? That's certainly what it looks like in the photo. € LED rear lights for bikes are said to be best when they use LEDs that are as monochromatic as possible. You should be able to check this using a CD (spectral test). € Rolf

wosis123

I’m using an LED spotlight bulb with a GU10 base in a simple spotlight fixture. I got the bulb from Conrad; it’s really bright and doesn’t cast any shadow on my Rollei paper (MCC 311, made by Foma) at all.

Olivinyl

Hello everyone, I’m using a red 0.67-watt E14 LED bulb from Osram. It’s very red and also very bright when used indirectly. No problem with Foma and ADOX paper. Only when pre-exposed paper is in the immediate vicinity of the lamp (approx. 30 cm away) does it start to fog up after about 90 seconds. The lamp is positioned approx. 2.5 metres from the enlarger and shines upwards towards the ceiling. Best regards, Oliver

StraDi

Hi everyone, There isn’t much discussion about the ‘colour’ of light for darkroom lighting. The manufacturer provides the relative spectral sensitivity for every decent paper in the technical data sheets. A glance at these makes any further discussion unnecessary. You will quickly find that almost ALL papers currently on the market (including Foma Variant papers) can be processed under subjectively ‘orange-red’ lighting from around 580 nm. This corresponds almost exactly to the main spectral lines of sodium vapour lamps (around 590 nm), as originally offered by Osram, Durst and others. LEDs are also ideal, provided you have the relevant datasheets to hand and can thus determine the exact wavelength (not all LEDs emit such a narrow-band spectrum). The same applies to Foma Variant papers. It is often claimed that, due to the higher sensitivity of these papers, only red light should be used. However, this confuses relative light sensitivity with relative spectral sensitivity. Consequently, these papers in particular can also be processed from around 580 nm. My own experience confirms this. I use exclusively an Osram Duka 50. The fog test shows no fogging even after 4 minutes when the Duka 50 is set to aperture ‘30’, with indirect illumination of a white wall from a distance of approximately 3/4 metre, and a distance of approximately 2 metres between the light source/white wall and the wet processing area. It goes without saying that darkroom lighting has no place near an enlarger, so that the effect of the light is, at most, limited to the wet processing time. In contrast, an Ilford SL1 and a similar Kaiser darkroom light with interchangeable plastic screens, positioned in the same way, showed slight fogging after just about 1½ minutes. These are simply coloured plastic screens, which can never be as narrow-banded. This also makes sense when considering the Type 902 screen recommended by Ilford for the SL1 for multigrade papers. Here, the screen’s spectral absorption ends as early as 560 nm. The absorption spectra specified in the ‘data sheets’ are, moreover, highly inaccurate. The earlier, simple, red incandescent bulbs often worked well because, on the one hand, incandescent bulbs have their maximum in the red wavelength range (extending into the IR range), the light intensity was lower and the photographic paper was less sensitive. There were also special varnishes for incandescent bulbs. Here, one had to take the utmost care not to miss any spots. However, low-pressure NA vapour lamps are the safest and also the brightest light source with the longest possible processing time. These were and still are recommended by many fine art printers. Such lamps are available new from reputable dealers for a price in the mid double-digit euro range and, if handled properly, will last for many years. Alternatively, LEDs with a narrow-band spectrum (check the datasheet!) are also very suitable. cu ... Dirk

Rolf-Werner

So I suppose that clears things up :) € Thanks for shedding some light on the matter so expertly. We had a NA vapour lamp like that in the school lab back in the early 80s, where I did my A-levels. We found the thing a bit unsettling because it was incredibly bright but didn’t seem to have any fogging effect. The lamp shone against the white ceiling in the adjoining room, where the paper was being wet-mounted, and everything was still clearly visible in the room with the enlargers next door. It hummed loudly to itself. Fogging occurred later with certain types of paper and because some people became careless and left the paper in the light of the lamp for too long. But otherwise: brilliant! € For the small room I’m planning now, the huge lamp would probably be too big. So I’ll have a look at LEDs; you can position them more precisely. I’ll ask for the datasheets at the local electronics shop. But they should be red ones, shouldn’t they? € Rolf

StraDi

Hi Rolf, No problem. :-) They should be red LEDs, that’s correct. Ideally dimmable, so the brightness can be adjusted. But here too, indirect lighting is an advantage. See you ... Dirk

TiMo

Aren't there three of them, each with a different brightness? That's certainly what it looks like in the photo. ? ?

? No, it’s just one panel; the one on the far left of the picture. But if you fit it in front of a 15W bulb, the room is almost pitch black.

Rolf-Werner

Well, that’s not really the point of it all. I’ve got two old Rowi lamps with green-brown filters; they were never very bright, but they did the job. I’d have to measure them to see if those filters would fit. On the other hand, you could always move with the times and go for LEDs. € Why do they show 3 filters when there’s only 1 in there? € Rolf

Renate

You can buy the other filters separately if you need them. I, for example, have all three. ? Best regards ? Renate

wosis123

I have a Duka 10, but with my paper (Foma), it produces a haze without a red filter after 3 minutes of direct exposure at full intensity from a distance of about 1.5 metres. The red LED light from Conrad (the LEDs aren’t even red; it’s pointed at a white ceiling from a distance of about 40 cm) doesn’t produce any haze at all. What’s more, the LED feels significantly brighter than the Duka. Also, the LED doesn’t seem to take a full minute to reach full brightness. Naturally, I switch off both lights when I’m measuring (Trialux) and performing exposure, as the warm-up time on the Duka is particularly annoying.

Rolf-Werner

It sounds as though you’ve fitted an energy-saving bulb instead of an incandescent one. Energy-saving bulbs have strong blue-violet spectral components, which you probably wouldn’t be able to filter out very well with a diffuser like that. Incandescent bulbs tend to peak at orange-red and have hardly any blue light components. € Now I’ve had an idea: if there are red LED bulbs with an E14 base, you could simply use those and just fit a white diffuser. Then you could continue using the old lights in a modern way :-) € Rolf

wosis123

Did you know that Dukas sodium vapour lamps have a special base?

StraDi

I have a Duka 10, but with my paper (Foma), it produces a hazy image without a red filter when exposed for 3 minutes with direct light on the paper from a distance of about 1.5 metres at full intensity.

? That is not surprising. It is expressly stated that the red filter should be fitted when processing black-and-white variable-contrast papers. This is important with the Duka 10 because the NA low-pressure lamp does not have its own narrow-band filter. The Duka 50 is fitted with different NA lamps, on which a filter is applied directly to the lamp bulb. Although the light can be regarded as monochromatic (at 589 nm and 589.6 nm), there may nevertheless be – depending on the design and age of the NA vapour lamp – a further (very weak, but ‘visible’ to sensitive papers) secondary peak at around 500 nm. This is not the case with the Duka 50; with the Duka 10, however, the red filter is absolutely essential. As already explained in my previous post, this does not cause any fogging, even with Foma papers. ? Regardless of this, it should also help to use indirect lighting and/or close the aperture slightly.? ? My Duka 50 has been in use for years with its original bulb. With the aperture fully open, it illuminates a room of around 12 square metres so well that you can work visually and even read very clearly in every corner. ? Given that LEDs are becoming increasingly affordable, these lamps are still ideal, but can easily be replaced. Nevertheless, it is sensible and necessary to check the LED datasheets. Not all LEDs emit such narrow-band light. To be on the safe side, a red filter should be fitted in front of them. Probably the biggest advantage of LEDs is their low power consumption and the fact that they produce no waste heat. ? However, as long as my Duka 50s are still working, I see no need to change them. ? cu ... Dirk

Rolf-Werner

You do know that Dukas sodium vapour lamps have a special base, don't you?

Oh – right, I hadn’t realised that... ;)

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