Direct Positive Paper

Simon Hendy

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Is this an alternative process? Well it's not film so I suppose it is!
I've had very limited success with DPP - strangely my results have got worse the more I've used it. I like to think I'm a reasonably bright chap but it took me far too long to realise that my mainly white sheets of paper were over exposed <sigh>
I'm determined to get it right as I love the look of the Imago paper - I bought several extra boxes of it after seeing the first images.

On of the early successes - lichen on a fence post in France.
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One of the wrecks at Purton Hulks near Sharpness.
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And the less successful!
I wish I could claim I was trying to produce a minimalist masterpiece, but I wasn't. This is at Aust, just outside Bristol, and a causeway out to a pylon across the Severn estuary.
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Another one of the Aust pylon.
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Old warehouse in Bristol - I'd realised what was happening by now, and bracketed a couple of exposures. This is the better one.
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And the most recent - autumn leaves on Clifton Down. Getting there!
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Ian Grant

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I have quite a bit of Harman DPP but haven't yet been inspired to use it. The Imago paper was made by Ilford Photo at Marly, Switzerland this was originally Tellko who came up with the predecessor of Cibachrome/later Ilfochrome and once part of Ciba Geigy.

It looks like you aren't pre-flashing which is very important cuts contrast and helps buid exposure (without fogging). The process itself is quite complicated and based on the Herschell effect where the emulsion is completely pre-fogged to one wave length of light and the exposure at a very different wavelengths destroys the latent image.

Ian
 

Nick Rowland

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I've tried both Imago and Harman paper, pre-flashing is the answer, as Ian says. You can recover the burned highlights with Lightroom after scanning but that's not the same as doing in in-camera.
 

Simon Hendy

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I have been pre-flashing - I can't remember offhand how much, but a few stops under with greaseproof paper as a diffuser.
 

Nick Rowland

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0.5 to 1.0 second f16 under an enlarger seems to work ok most of the time. You do sacrifice black depth as a result though. It isn't an exact science, I've wasted a lot of paper.
 

Ian Grant

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0.5 seconds at f16 probably close to the maximum flashing exposure I use with conventional B&W papers before fogging occurs. It's probably worth using an enlarger meter to measure the exact exposure intensity for repeatability.

Ilford actually mention a pre-flashing exposure of somewhere around 3 seconds exposure at f16 with an enlarger, with no diffusion, but of course enlargers differ in intensity, no mention of column height is being made. However the pre-flashing needed is greater than with conventional papers.

Ian
 

Ian Grant

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With conventional printing it doesn't make any difference. It probably doesn't but it's recommended to pre-flash before use.

Ian
 

David M

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We seem to have two variations of flashing here – the usual system of giving a bit more "ordinary" light through a diffuser, to help boost shadow detail and Ian's system using specific wavelengths. I'd like to hear more about this.

In the darkroom, some people like to pre-flash a batch of paper, My experience is that before or after makes no difference. I made flashing test strips instead of batch-flashing.
In the field, it seems sensible and practical to do "ordinary" flashing of film on a case-by-case, image-by-image basis. Each scene will be different and flashing can't be undone. I'm not sure about the mechanics of batch-flashing film. DPP may be different.
We should probably keep in mind that flashing affects different ends of the tonal scale depending on where it it applied – shadow detail in-camera and highlight detail in the darkroom.
This is for normal film and paper. We are discussing direct positives here, so things will be different. How different are the rules for DPP? Is there more to it than everything being the other way round?
 

Ian Grant

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Pre-flashing with an enlarger is a recommended method that's been in use for many years. It's also Ilford's method in their Direct Positive data-sheet it's done with no filtration so not to s specific wavelenght. Remember Direct Positive emulsions are prre-fogged to a specific wavelenght of light and use the Hreschell effect to detsroy the latent image selectively during exposure.

Other systems have been used some slide copiers used a fibre optic system to add the flashing exposure simultaneously to the main exposure, this was adjustable. B&W roll-head printers used a fixed grade paper and flashing exposure to control the contrast in the 50's and 60's and many of us will remember the bland results.

Ian
 

David M

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Aha!
I've misread your earlier email. I had thought that this kind of flashing was something that could be used by the end user.
A second question, then. Would it be possible to take ordinary paper and put it through the same kind of controlled pre-fogging? I'm assuming something like using an enlarger with a colour head. I'm asking because I like to know, rather than because I propose to do it myself, at least in the near future. It would be easier, of course, simply to buy the proper paper.

I remember the Bowens slide copier with its diagonal glass. I never used one, but I understand, from what my friend told me, it could be used for both contrast control and colour correction.
 

Ian Grant

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In theory it might be possible to pre-fog ordinary paper for reversal use but in practice it's not feasible. All the direct positive emulsions are (or were) relatively high contrast. Kodak sold a Direct Positive duplicating film which was excellent for making enlarged negatives for alternative processes, and they had direct positive films for the printing trade.

The Harman Direct Positive paper originally used emulsion made by Ilford in Switzerland, it was in fact the basic Cibachrome/Ilfochrome emulsion. When they finally ceased manufacture Harman had to negotiate with the receivers to get the rights to manufacture the emulsion themselves.

I'm sure you could do the flashing exposure using a diffuser and probably an ND filter, ideally you'd want a meter that has an EV scale, then use a standard time and vary the aperture to give the correct exposure.

Ian
 

Nick Rowland

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This guy has done a lot of experimenting with DPP and paper negs. In the comments in this video Joe mentions how he flashes the paper.
 

Ian Grant

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I didn't see any mention of pre-flashing in the video. I have a few boxes of 5x4, 7x5 and possibly 10x8 Harman DPP so it's time to give it a go :D

Ian
 

Nick Rowland

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It was in the comments below the video not the video itself, he has a separate video on pre-flashing for paper negatives (not dpp)
 

Ian Grant

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Thanks Nick, took a bit of finding. It's a rather important aspect of using the paper so I'm surprised he made no mention of it in the video.

There's a new Italian two part reversal kit, however when youn watch the latter part of the video it's not quite as new a process ans initially indicated.


When I was a student at university in the early 1970's we had a lecture from a research student from Birmingham School of Photography (at that point headed by Michael Langford0,, He was working on reversal processing and making B&W reversal prints made from B&W reversal negatives, the quality was superb but he said there wasn't the tolerance and controls afforded by the negative/positive process. He was using FP4 and printing on Ilfobrom, it was before the introduction of RC papers.

I have a project where I want to make reversal prints, it's on hold at the moment one problem is Ilford don't sell their DPP paper in British sizes apart from 5x4 and 10x8, I'm after Half Plate, Whole Plate, 12x10 and 15x12 as well, and it needs to be precisely pre-cut. In addition for speed (washing and drying) I really need an RC paper. So I'll be looking at Reversal processing instead of DPP, this was a project I was discussing with a former director of Harman Technology (Ilford).

Obver the years I've researched reversal processing of films (for commercail use) so will try with paper this Spring. One possibility is the fast paper Ilford make for their converted Fuji Frontier minilabs and Lambda printers.

Ian
 

Ian Grant

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For half plate I cut down 5x7 using a tinplate as a template. It is fiddly doing it though
The original owner of my Kodak Specialist 2 was ctting 7x5 FP4 to fit the camera's Half Plate DDS, I'm just going to use 7x5 DDS as I have plenty. I bought the camera of his grand-daughter, the box of FP4 had an expiry date of 2002 which roughly indicates when it was last used, Half and Whole plate films were still available when I started using LF in 1977 but being with-drawn :D

The issue for me is working with vintage British cameras and book-form plate holders, I just don't want that fiddly cutting down.

Ian
 

Nick Rowland

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I can relate to that with my half plate Lancaster Instantograph. I have just finished making an adaptor to use a Graflok 5x4 back on it as cutting negative film doesn't do it for me. My next plan is to either adapt a book-form to take 7x5 or make one from scratch, not sure if my wood-work will be accurate enough though. I do prefer the larger format to 4x5.
 

Ian Grant

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I was lucky and bought 3 half plate backs a couple of tears ago, one's a Gandolfi spring back but doesn't fit my camera, it should take modern 7x5 DDS I'll look tomorrow. One was a 7x5 spring back damaged but I've repaired and re-fashioned it (grafted on wood so it fits) to use it on a 7x5 Seneca City View. As these are Black Ebonised finish cameras the modifications can't be seen.

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

Ian
 
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