Direct Positive Paper

Ian Grant said:
Let me have some dimensions of your Gandolfi's back, I've no current plans to use this one.

Ian
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Which dimension do you need, external size or in the recess? It's a Lancaster rather than a Gandolfi Ian.
 
I've replied by PM, I'd need the two dimensions external and internal recess, however I don't like the idea of butchering a Gandolfi back or I'd have done this myself :D

A couple of years ago I made a 6x7 back for a MF field camera I built, that included the GG screen hold etc. It wasn't difficult would have been easier if I had Alan Clark's wood working skills and tools though.

Ian
 
I shot quite a lot of Harman DPP last year and took copious notes. I'll see if i can dig them out and let you know how I went about it. There was definitely pre flashing going on with a couple of layers of white paper.
 
Any notes would be useful Brian. I have a few boxes of Harman Direct Positive paper including some of the RC version which was only successfully coated once. The second coating run failed and had to be scrapped and no RC DPP paper has been coated since.

Ian
 
OK, looking at my notes, I rated the paper at ei 6, metered the scene then preflashed through a double sheet of Hobbycraft tracing paper at 3 stops under then shot again at the metered exposure. This certainly cut down on the contrast. I'm going to buy another box and have another go now that I have access to a proper darkroom and not just some developing trays in a bath!.
 
Resurrecting this, I thought I'd experiment trialling how much of an unflashed image would be recovered with digital scanning. I asked a pal to pose (no apologies for composition) and used 5x4 Imago DPP with full sun on the subjects face, to get widest dynamic range/extreme contrast. I was quite surprised how well it performed (see images below) with a scan to jpg file. I expect a tiff/dng would be even better but the file size and scan time tested my patience too much.

Ok, it's not the same as doing it all in-camera but I was curious.

Nick

First image is a scan unprocessed and the second after some slider work in LR. Developed in Ilford Multigrade.17081709
 
I'm having a play with this DPP but I noted somewhere (possibly from an ilford video) that you need to preflash the paper within a couple of hours of using it otherwise the silver goes back to how it started. With this in mind and also noting that they said develop as soon as possible how long after taking a photo can you keep these photos before the photo detail is lost? I may well be missunderstanding the whole thing but it does seem logical to me that if the preflash will dissappear that the photo will do the same
 
There are numerous accounts of flashing. Before or after the main exposure? Immediately or in advance? A whole batch or one at a time?
All these accounts seem to be from people who’ve used it successfully, so it probably doesn’t make much difference.
Exposed film seems to retain the image for years. We know this because there’s a fairly plentiful supply of forgotten rolls of film. No reason to suppose that paper differs very much. Paper can lose contrast, but that’s over years of storage.
My own, very limited experience is that flashing is much more effective on paper. This was under the enlarger, not in camera, but photons are photons. I found less difference with film. This may be entirely the result of incompetence or misunderstanding. Other members will have better advice.

The best system is to test on your own set-up.
 
Thanks David, I guess that flashing doesn't give enough light to complete the process change but full exposure does which is why it remains there. I'm experimenting at the moment but I like the idea of in camera flashing because I'm not set up with a darkroom yet and just use my tanks for developing so if I can continue by using a white mask over the lens for the preflash I'll be happy. I actually got two different plastic diffusers to try one sided and two sided so I can see which works best for me. So I'm just playing to see what is going to work with what I've got.
 
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