Stefan_BL
Hi everyone,
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Just a quick word about myself, as I’ve only just registered here. (It was the only darkroom forum I could find :rolleyes: )
I’ve been dabbling in photography and developing for nearly 18 years now. I have ‘two’ darkrooms: one for quick, small-scale jobs with few prints, and one for ‘batch printing’ and large-format work... For a detailed description, see the ‘About me’ page.
I take photos strictly on film – somehow digital cameras just can’t compete with good film. I have a mini-studio (50x60, approx. 70cm high) and a mid-sized studio (backdrop up to 4m wide and 2.5m high). When it comes to lighting, I swear by flash...
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Actually, I have three queries, but I didn’t want to create a separate thread for each one...
1.
Does anyone happen to have any experience with building Wallner (B/W) light meters? I’d like to build one for my Universal II.
I’d be interested to know the type of photodiodes used (resistance, positive or negative curve, power supply), as well as the height of any diffuser plate used above the photodiode/photocell.
2.
Just out of sheer collector’s instinct – does anyone happen to know a source where I can download and print out manuals for my Magico and the RCP-20?
3.
Has anyone here ever modified an RCP-20 for adjustable speed and independent temperature control?
Thanks
Stefan
Wolf_XL
Re 1:
Have you ever considered how much it would cost you to build a replica of a Wallner light meter, for example, if you were to factor in your own hourly wage? Just buy a Wallner light meter with a suitable light-sensitive cell on eBay – that’s quicker and guaranteed to be cheaper than any attempt at building one yourself...
Re 2:
I could scan the RCP 20 manual and send it to you if you need it...
Re 3:
No. What’s the point of that? If the processing speed isn’t right, I can compensate for it with the temperature. And the fixer temperature is pretty much irrelevant in the RCP processes I’m familiar with...
Stefan_BL
Hi Wolf,
Sorry it’s taken a bit longer to reply...
Re 1:
It’s quite an old piece of kit. I’ve already had a look at a few others from Wallner – but unfortunately none of them fit (they have DIN plugs).
It uses a good old-fashioned speaker socket as the connection...
So the sensing cell can’t be particularly complex (no dimming control or similar) and probably only has a photoresistor, and perhaps a few components for voltage adjustment...
So I really just need to sort out the ‘mechanical assembly’ and find a suitable photoresistor.
Unfortunately, there are loads of the latter – so I’d be interested to know what type (or at least the key specifications)...
And as I said, the construction of the housing...
Re 2:
That would be brilliant...!!!!
Re 3:
I’m not necessarily a fan of adjusting the chemistry to the speed.
I can’t imagine that, in terms of quality, it makes no difference whether you run the developer at ‘normal temperature’ or crank it up to match the speed...
I’d envisaged a small display and a microcontroller. That way, you could define different profiles and run them accordingly.
Basically, pre-programming processes and paper types and that’s it. Because even with supposedly ‘identical’ PE papers, there are already differences in development time. (Compare Ilford and Foma).
Okay, there might be a bit of fiddling about or daydreaming involved, but I reckon it would optimise my lab :rolleyes:
Thanks
Stefan
Wolf_XL
Hi Stefan,
Re 1:
I think I know which measuring cell it is, or rather which Wallner model the measuring cell in question belongs to. I might even have one of those lying about somewhere. The measuring cell sits on a metal stand – but that only really allows for something like ‘mid-frequency integral measurement’. My opinion: Scrap it and buy something more modern – you won’t really be happy with that.
Re 2:
...then send me your email address...
Re 3:
Yes, it’s possible. Since you have to develop the paper in the black-and-white process anyway, the temperature just needs to be high enough to ensure the paper is fully developed. In my RCP, converted to RA-4, I run it at 30°C. ADOX MCP 310 in the tried-and-tested Orwo N113 comes out of the machine perfectly developed.
Think about it logically: where on earth would the difference come from? Whether the print stays in the bath for three minutes at 20°C or one minute at 30°C makes little difference to the result...;-) You don’t need to experiment too much with this either – if, for example, your paper would be fine with a shorter development time or lower temperature, it doesn’t matter; you can’t develop it any further than that... You’re simply offsetting the change in one parameter by adjusting the other...
Stefan_BL
Good evening Wolf,
Re 1:
I actually only want to use the measuring station for my bench-top lab to get a quick idea of the situation; the rest will be done using test exposures.
It’s a bit of a quick-and-dirty approach :rolleyes:
When I’m doing something that requires a certain standard of quality, I work in my ‘normal’ darkroom. I don’t have any Wallner measurement equipment – but I do have decent analysers from Philips... They’re from the 90s, but they’re brilliant to work with...
Re 2:
I’ve just sent you a private message
Best regards,
Stefan
