Is a Janpol enlarger lens capable of getting the filtration for RA-4 direct positive?

[arnoud bakker]

hello all,
I was wondering if a Janpol color enlarger lens was capable to filtrate light, so it can be useful for the RA-4 direct positive process?
anybody? best regards! Arnoud Bakker.

 

[koraks]

I understand (but have not used) the Janpol lens to be a lens with an integrated and adjustable dichroic filter stack intended for color negative enlargement. As such, it can be expected to perform the same or similar as a regular dichroic enlarger head. I understand that only two filters can be used at the same time, but this should be OK since you technically never need all three anyway. Looking at the filter adjustment range, I'd expect you have enough filter room for this particular purpose. You may experience some benefit from adding a blank piece of orange-masked C41 film to the light path to bring the filter corrections closer to what the RA4 paper expects.

 

[MattKing]

IIRC, one of the reasons that almost all dichroic colour heads include a cyan filter adjustment is that with Cibachrome/Ilfochrome and Kodak R (print from slide) prints, sometimes it was advantageous/necessary to use that cyan filtration.
So your question is a good one.
I don't know whether @koraks suggestion will help, or hurt .

 

[arnoud bakker]

it is just an 20 euro guess... and worth trying..
guess I'll change the 80 mm lens parts for 150mm (or more )
everything to make it simply work outside.. and..... it does not have to be perfect..

 

[brbo]

That's the spirit!

If it works (no additional filtering needed and the filtering part of the Janpol color lens can be fitted to other lenses that can cover LF) it will simplify direct RA-4 considerably.

 

[koraks]

it is just an 20 euro guess... and worth trying..

Definitely!
You need some paper to try this out with? Drop by and I'll give you some.

 

[arnoud bakker]

I just placed a bid on eBay, and sooner or later there will be a Janpol
I do have paper, although the inventation is nice and I'll drop by soon!

 

[koraks]

Good, let's keep in touch!