andreasdegner
Hi everyone!
Yesterday I carried out various veiling tests using different types of paper, using a red DuKa lamp (the cheap one from FOTOIMPEX with a 10W bulb) and the Ilford SL1 (15W). The lamps are each mounted approximately 1.20 m above the wet processing area. I pre-exposed the photographic paper so that a light grey would appear. I then placed the sheet under the lamps at the aforementioned distance and exposed it twice for 5 minutes each (i.e. one streak for 10 minutes, one for 5 minutes and one that was not exposed to the DuKa light). The results were quite interesting:
Ilford MG IV:
With Ilford light, only minimal (but noticeable) fogging. With red light, however, the fogging was considerably stronger! How can that be? As mentioned, the red light has only a 10W bulb (and is much dimmer than the SL1). Besides, it’s always said that red light is always safer when in doubt.
Has anyone else had similar experiences with the FOTOIMPEX lamp? I get the feeling that it emits too much non-red light.
Adox EasyPrint Vario Classic:
Also causes noticeable fogging, though significantly more so with SL1 than with red light. According to the datasheet, however, orange should work too!?
Forte Polywarmtone PE:
Similar results to ADOX
Conclusion:
The distance between the lamp and the paper, at 1.2m, is probably far too short. How have you set up your darkroom lights?
And how do you manage this during lith development, where the paper is sometimes exposed to the darkroom light for 15 minutes? Surely the fogging should be even more noticeable then?
At least I’ve now found a reason why I can’t achieve satisfactory contrasts – precisely because of the fogging. This only becomes noticeable from the light grey tones upwards, whereas white remains white.
I look forward to your replies!
Best regards,
Andreas
martinhampf
Hello Andreas,
I’m using a Kindermann Dulux SL. The red light is produced by the red cap over the bulb. The lamp shines onto a light-coloured ceiling, about 2 metres away from the tank.
A veiling test revealed some fogging with the current setup. I then painted the bulb with orange poster paint and since then everything has been fine (at least according to my veiling test ;-))
Kind regards,
Martin Hampf
Renate
Hello,
All filters always allow a limited amount of other light colours to pass through. Red filters that I have tested with a spectrograph still show traces of green light, and contrast-sensitive paper reacts to green light. Double filtering helps very much to suppress the harmful light components more effectively. For example, you can paint the bulb with a red-filtering paint.
Incidentally, the situation is similar with red light-emitting diodes. Even the dark red LEDs I use still produce a faint, but for the paper visible, component of green light. That is why I pass the light through a dark red filter again and shine it indirectly onto the wet area via the ceiling.
The red filters on the enlargers are not perfect either and can obscure the paper. It depends on how open the aperture is and how long it takes to align the paper. This is often overlooked.
Best regards
Renate
andreasdegner
Hello Renate!
Where can I buy that sort of red paint?
cfb_de
Hello Renate!
Where can you buy that sort of red paint?
Hello Andi83,
I’ve already mentioned this here before: it’s called “peel-off paint”. It was once on sale at a competitor’s and is still available from the usual specialist art supply shops or from paint suppliers:
http://www.pietzckerfarben.de/index_f6_loesemitl.htm, and in small bottles from "Diaphoto" – also available in photo lab supplies.
Best regards,
Franz
hansschneider
Dear Andreas,
Thank you very much for sharing your results. However, regarding the times
>>i.e. one streak for 10 minutes, one for 5<<
one has to ask how on earth anyone manages to expose photographic paper to red light in the darkroom for five minutes or more?
My calculation looks like this:
1. Take the paper out of the box (it lies there with the emulsion side down), carry it to the enlarger (also with the emulsion side down): five seconds.
2. Place the paper in the (Versamask) frame: five seconds.
3. Put the paper into the developer (emulsion side down): two seconds.
In total, I arrive at a maximum of about 15 seconds during which the paper is indirectly exposed to the red light.
In that respect, I consider the five seconds you’ve chosen—and even more so, of course, the ten seconds—to be unrealistic.
It would be interesting to see measurements with times of 10, 20, 40, 80 seconds (e.g. a sheet slips out of your hand, you have to fiddle with something – all of which are exceptional cases, of course).
Best regards
Hans
andreasdegner
Dear Andreas,
Thank you very much for sharing your results. However, regarding the times
>>i.e. one streak for 10 minutes, one for 5<<
one has to ask how on earth anyone manages to expose photographic paper to red light in the darkroom for five minutes or more?
My calculation looks like this:
1. Take the paper out of the box (it lies there with the emulsion side down), carry it to the enlarger (also with the emulsion side down): five seconds.
2. Place the paper in the (Versamask) frame: five seconds.
3. Put the paper into the developer (emulsion side down): two seconds.
In total, I arrive at a maximum of 15 seconds during which the paper is indirectly exposed to the red light.
In that respect, I consider the five seconds you’ve chosen—and even more so, of course, the ten seconds—to be unrealistic.
It would be interesting to see measurements with times of 10, 20, 40, 80 seconds (e.g. a sheet slips out of your hand, you have to fiddle with something—all of which are, of course, exceptional cases).
Best regards,
Hans
Hello Hans!
You’re certainly right that 5 or 10 minutes is too long for normal work. However, you can easily end up in the range of minutes if you still have to trim a sheet of photographic paper under red light and are using a slightly slower developer (plus baryta paper, where the exposure time can easily be 20–30 seconds and development takes 2 minutes). Not to mention warm-tone papers, which need to undergo exposure for a minute or longer with large formats. If you then had to keep switching the darkroom light off again, it would make working in the darkroom much more inconvenient. I just wanted to be on the safe side with this test. In any case, I’ll try to set up my lighting so that I’ve got nothing to worry about at 5 minutes.
When developing lith prints, however, it should be enough to switch on the red light now and then to check the development progress, and leave it switched off otherwise.
Best regards
Andreas
HenningH
Hello,
Many exposure timers switch off the Duka light whilst the lamp in the enlarger is on. My old Jobo couldn’t do that, so I got hold of an extension lead with a pull-cord switch and attached it next to the enlarger board, so that I could operate the lighting more easily than using the timer...
Best regards,
Henning
andreasdegner
Hello!
I have repeated the test, with the following results:
Even after 8 minutes, the Ilford MG paper shows no fogging when used with the Ilford SL1 at a distance of 1.5 metres (with the lamp folded upwards, so that only indirect light falls on the work area). The work area is sufficiently bright, as my walls are painted white.
However, I’m still having problems with the ADOX Easy Print and the AP red light from FOTOIMPEX: even at a distance of 2 metres, the ADOX paper is visiblely fogged after one minute.
What Duka lighting do you use for ADOX papers? I get the feeling that the AP lamp is simply unsuitable for ADOX paper (though there was no such indication on the Impex website).
Best regards
Andreas
Wolfgg
Hello Andreas!
"The workspace is bright enough, as my walls are painted white."
This is often the reason why enlargements don’t turn out properly brilliant. The stray light emitted by the enlarger and the projected image is often underestimated. There should be no white surfaces near the enlarger. This also includes the bad habit of holding your beer belly next to the paper in a bright white lab coat during exposure. Black paper, fabric, etc. on the wall next to the enlarger and a grey lab coat will remedy the situation.
Regards, Wolfgang
andreasdegner
Hi Wolfgang!
Thanks for pointing that out. I’ll give that a go soon. As I have a white base board that reflects light quite well, that’s a real source of error.
Best regards
Andreas
Wolfgg
One more tip: there are even types of photographic paper that are affected by the light reflected from the white surface beneath the paper. To test this, simply place a sheet of black paper underneath a sheet of photographic paper; after development, you shouldn’t be able to tell from the image where the black paper was positioned.
Best regards, Wolfgang
