RA4 Colour Reversal Process - Paper Negs

[sidestepper]

Hi there all,

I’m interested in shooting colour paper negatives and processing in camera... I’m new to this forum and was hoping I might be able to find some help. (I have searched through previous threads but can’t find what I’m after).

I have a giant camera I built out of an caravan (I think they’re called campers in the States), I use massive old ariel and process lenses (the 1210mm apo nikkor for instance) and currently shoot straight onto 16x20” Ilford RC b&w paper, I then develop inside the caravan with normal dev/stop/fix/wash trays. I then contact print the paper neg put it back through the trays to create a b&w positive image. I use it to teach photography, how and camera works and the basic analogue process running workshops with different groups of people.

I’ve been wondering if I can do the same with colour, but figured it would be too complicated, but then I saw a video of a ‘ra4 reversal process’.

Basically, can anyone advise me on how I could make colour paper negs inside my camera. There is plenty of room for trays/tanks etc.. but it has no mains power so I’m running on batteries and solar.

I have seen a video which looks like someone places a b&w neg into a tray, in the light, and it turns to colour!

What is happening here?!

Any help would be much appreciated

 

[1kgcoffee]

I've heard of this being done with colour filters and the 8x10 reversal prints looks amazing. The dynamic range is somewhat poor however. Would be very interested to see your results if you manage to figure this out.

Here is an example from flickr with some clues in the comments:
https://www.flickr.com/photos/wayne.../photolist-bT797z-bSK6BV-dLJCvi-dLHQgD-8hSnu7

Joe Kirschling 7y

no.. I don't have any mottling on mine.

I did get some advice from Photo Engineer on APUG once.. I have been meaning to try this for a while. Custom Dektol with half the bromide..

Joe;

I mixed Dektol with no Bromide (D-72). I then added bromide slowly until I got the right value. In the concentrate, the bromide was about 1/2 what it is in the original D-72 formula. I used this at 1:3 dilution for 2 minutes at 68 deg F.

For the color developer, I used about 1/2 g - 2 g/L of Sodium Sulfite added to the developer. This varied with respect to paper batch and the desired effect. The pictures moved on the red - cyan axis in balance with this and the contrast was lower.

I have never tried Fuji. My comments were based completely on posts on APUG and Photo Net.

Ron Mowrey

 

[himself]

Hi,

I've done this with large paper colour paper in the past and it's not hugely complicated or that difficult.

The hardest part is figuring out the filtering you need for the paper. As you may know colour paper is colour balanced for enlarging from negs and so without any colour filters will print out blue/cyan resembling a really high contrast monochrome blue image. There's a thread here with all the details on the reversal process (a discussion on enlarging slides, but the principal is the same), but the basics of it are:

expose with filter pack (I use cibachrome filter sheets) over lens.
dev in black and white developer (making a negative print)
stop
wash
*stages above need to be done in total darkness*

re-expose print (the more the better, which is why you do it in daylight
dev in RA4 (print will turn positive
blix
wash

and that's it

It's a fairly quick process and takes about 10/15 minutes once you've made your exposure, but there are a couple of issues. getting the filter pack right takes a lot of trial and error, and small differences in exposure and developing at both stages can cause colour shifts, on top of the normal issues associated with RA4. There are also problems with mottling on the final print, and the final mages will usually be very high contrast (there are ways to modify that a little). It's not totally clear what causes the mottling, but it seems to be worse when the print isn't developed enough at the black and white stage.

I hope that helps for a start, and any more in depth details you want to know just let me know.

And finally
Where in the UK are you based? I'd be interested in seeing your camera if you're anywhere near south Wales.

 

[John51]

What about making RGB paper negs? Registration would be a hassle but seems like a problem you can handle. Would get interesting if the clouds were selfish enough to move during the 3 exposures but that could look cool. Hey, lomography.

For getting the RA4 chems up to temp, a slow cooker on low only draws about 40 watts. Run it off an inverter and use a light dimmer to control the water bath.

 

[bvy]

I was using 85B+50M+50Y for filtration in camera. That seemed to neutralize the colors, but it adds density. You'll have to experiment. Lots of variables in this process.

 

[koraks]

For getting the RA4 chems up to temp, a slow cooker on low only draws about 40 watts. Run it off an inverter and use a light dimmer to control the water bath.

Just use RA4 at room temperature; development takes a little longer but it works nicely.

 

[Daire Quinlan]

I've tried this, the shot linked above is a good example of a problem I couldn't get around, namely the mottling, which is particularly bad in the shadows. Also the filtering, as above, takes a while to dial in and results in long exposure times. This was as far as I got before I gave up and went back to straight RA4 paper negs



Other people have had more success. I didn't really have the time to devote to it ... at the time

 

[koraks]

I saw the mottling as well with direct paper positives on rc paper. I think it's the unevenness of the coating which becomes apparent as you only effectively end up with using a fraction of the emulsion. I'm afraid it cannot really be eliminated.

 

[mard0]

I can't really properly see the mottling on the tiny screen that I'm using at the moment. But I can add that I've seen a lot of mottling when using fuji CA2. Also when using this paper to print negatives.