Orwo filters for Duka lamps

Phil_2000 · 2003-07-24T19:53:34+00:00

Hallo, ich bin zufällig auf eine alte Ost-Duka-Funzel mit passenden Orwo-Glasfiltern gestoßen. Dabei sind die Typen - "107" (rot), - "112" (hellgelb, matt...

Phil_2000

Hello, I’ve just stumbled across an old East German Duka torch with matching Orwo glass filters. The types are - "107" (red), - "112" (light yellow, matt), - "113 D" (yellow-green, matt, dark) and - "113 I" (yellow-green, matt, light). I intend to use the lamp exclusively for processing Fomabrom, which can tolerate yellow-green light. Which filter is best suited? Is the lighter or darker yellow-green filter better for Fomabrom? Is there still paper available today that can tolerate the light yellow filter? Many thanks. Best regards, Philipp

Wolfi

Hello, I have an old photographic laboratory manual from 1971 which states that filter No. 112 (light yellow, matt) is suitable for contact papers (chloro-silver papers?) (direct illumination: 15-watt bulb; indirect illumination: 25-watt bulb) Filter No. 113 D (yellow-green, matt, dark) is for direct illumination of enlargement papers with a 15-watt bulb. Filter No. 113 I (yellow-green, matt, light) is for indirect illumination with a 25-watt bulb. Filter No. 107 (red) is for highly sensitive orthochromatic emulations and screen-printing films, for direct illumination with a 15-watt bulb and a 20- or 40-watt bulb for indirect illumination. I’m not sure if all this information is still correct. The book is from 1971! But I hope it helps you! Best regards Wolfi

Gast

Hi lads, Basically, I’d just try all these things out. (Kodak Safelight test: basically, cover half the test strip and leave the other half uncovered; expose one half in steps up to 30 mins or 1 hour, develop, and check for edges). The reason is simple: - Filters age; I’ve no idea how dense yours still are - The specifications are based on boundary conditions, e.g. processing time from unpacking to stop bath; what exactly is indirect lighting, or how well does your ceiling reflect light? - etc.... Generally speaking, any light provides exposure to any paper. The sensitivity curves do not all drop off infinitely steeply. But if you can stay 2 f-stops below the first discernible edge with your process time, that’s good enough! I work with an LED light, which for our purposes can be regarded as purely monochromatic red. It also provides exposure to the paper if I place the lamp directly on it. As soon as I keep a distance of 30 cm, I can even spend 20 minutes searching for marks next to the lith bath without getting any fog. And choosing the right paper for the filter ;-? Regards Martin

Phil_2000

But I hope this helps!

Thanks, that was really helpful. Best regards, Philipp

Phil_2000

And choosing the right paper for the filter you’re using ;-)

Hi Martin, I’ll definitely be doing a veil test soon, but a basic classification of the filters would be a huge help. Of course, I don’t choose my paper based on the light I’m using either. I use only Polywarmtone RC and Fomabrom. The Polywarmtone is developed in the drum (so no light is needed), whereas an additional light came in very handy for the Fomabrom. And I just wanted to know if one of the filters would work. Incidentally, I was interested to know if there is any other paper that can tolerate pale yellow light. Nothing more. Best regards, Philipp

Gast

Hi Phil, peace and goodwill ;-) I’ve had a few lights/bulbs that, in theory, shouldn’t cause any veiling, but when you look for light in a darkened room, the filter or the lamp coating has softened over time. However, my (admittedly subjective) experience is that a single light is better for everything, because I get used to the shift in perception (the print looks too dark in the developer) or can gauge it. The only place where I’d like a bit more white light would be lithography, because of the colour tone, and there’s hardly any room for that due to the development time. So, one lamp for everything. Incidentally, I find the LED light in question unbeatable in terms of the light/brightness ratio versus resistance to fogging. (It’s not the famous Kaiser with the selected LEDs, but a homemade one; however, with 80 super-bright LEDs, the cost of materials alone is already on a par with the Kaiser.) Good luck.

cfb_de

Hi Max, > one light source is better for everything, because I’m getting used to the shift in perception (the print > looks too dark in the developer) I do the same. Call me old-fashioned, but my ancient Agfa lamp glows red and, combined with the light-coloured tiles in the bathroom, is easily bright enough for reading the paper. I’ve fixed the filter up with a DC-Fix film. Best regards, Franz