The Paper Negative

[Hertz van Rental]

Is there a printed or web reference with even more detail? I find it all quite facinating.

I'm afraid that the short answer is 'no'. Or at least what work has been done in this area is highly specialised and the papers that have been written are very technical. There is nothing of a practical nature that I have found.
Most of the work that has been done is centred around Astronomy, as that is where the bulk of low light level exposures takes place. The best paper on the subject I have found (but I have to admit to not having looked very hard) is in the Annual Review of Astronomy and Astrophysics for 1979 - Advances in Astronomical Photography at Low Light Levels by Smith & Hoag. http://adsabs.harvard.edu/abs/1979ARA&A..17...43S - but be warned, it is very specialised and most of it is to do with hyper-sensitisation.

As for 'flashing' during and after exposure. If you understand the theory of latent image formation (electron movement, nucleation, that sort of thing) then you will understand how it works.
I won't go into it here, though, as it would take me about a half-an-hour lecture with diagrams and a short quiz after to explain it properly.
I will say that the illumination level required for post-flashing is extremely low - an exposure of around 30 minutes would be required to make an appreciable fog on the emulsion.
The figure of 5% for pre-flashing is just a starting point and easily arrived at.
The exposure required is just below the one that makes an appreciable fog on the emulsion.
5% is 1/20th.
If the exposure for mid-tone grey is X.
Then the exposure to just record shadow detail is X - 4 stops (or X/16)
1/20th will be just below that and on the threshold of exposure. Simple.

 

[mysteryscribe]

easy for you to say.....

 

[JamesD]

Thanks, Hertz. I've skimmed that article, and it's interesting stuff, particularly since I'm a technically- and scientifically-minded person (believe it or not), and my favorite scientific field was always astornomy (followed by physics and chemistry).

You've been quite helpful in this little endeavor; hopefully, it'll result in something handy for future paper-negative photographers (assuming we're not the last).

Looks like I've got a bunch of experiments to try this weekend. But right now, I'm gonna go take some pictures before the sun goes down.

 

[mysteryscribe]

Well from the non scientific member of this expedition in search of the paper negative, let me say, "There is a place in my bag of tricks for the paper negative."

Funny but today I shot two film shots and wished I had loaded one side with paper. I think the subject might have been better on paper. Smoother paper negative prints have a more retro look about them. At least that's my thinking today.

 

[JamesD]

Before I do anything further, I need to calibrate my exposure process... and write it down. Apparently, memory is not serving. I went out to get some pinhole images before the sun set, and I'm glad I came back after exposing just one. It was hopelessly overexposed, and if I'd used the same metering, I'd probably have wasted all the paper.

I think what I'm going to do is make several shots of the same subject, from completely underexposed to completely overexposed. This will give me a couple of guides:

1. An indication of the metering correction I need to apply.
2. A visual incication of which way I need to take the exposure next time I try that or a similar subject in that or similar lighting.
3. A guide for printing less-than-optimal negatives when I fail to expose correctly.


I'll likely do the same thing with prints of the optimal negative to give me a ballpark figure when I'm printing.

I should probably do this for both bright-light and low-light situations. And, of course, I'll have to do it all over when I start using the view camera.

 

[JamesD]

Well from the non scientific member of this expedition in search of the paper negative, let me say, "There is a place in my bag of tricks for the paper negative."

This is a great quote!

 

[mysteryscribe]

James I'm not sure how you are doing it but It drove me nuts for a while. I do it this way... I set my meter up for 5 iso. I read the meter and shoot it. I have a chart that coverts ev to time at the fixed aperture.

I also ad 30% to 50% exposure if the time exceeds one minute. Since I develop in a daylight tank I never get to see the neg till it is done. I always develop mine the same.... 1oz dektol /1oz d76 to 4oz water.. for two minutes at 68 degrees. That has been the most consistant for me so far.

It is probably a good place to start, but not likely to be what you need you are making contact prints where I am putting mine directly onto a scanner.

 

[JamesD]

Okay, I think I'm leaving the paper neg + pinhole to daylight only. I've spent the last couple of hours exposing repeatedly, and have yet to arrive at a workable negative. It's simply too long an exposure. I will say this, however: I preexposed the paper under my enlarger for five seconds, f/16, at the lowest light setting, just to the point where it didn't fog when developed, and it does make a difference in the image. The main effect is that it brings the image out, equivalent to perhaps one stop of exposure. Not much, but still visible. Considering that the last exposure I did was 30 minutes, and would likely need to be at least two hours... that's two hours knocked off--quite a difference.

I may revisit ph+pn later on in life, but for now... nah. Paper negs, however, still fascinate me, and pinhole still fascinates me. I just don't have the patience for them together right now.

Tomorrow, I begin on my biggest project ever: the view camera. I'm not sure how long it's going to take, but I might have it done by sunday. It's hard to say. Once it's complete, however, I'm going to begin by using paper negs in it, and later on, perhaps film. When I've got it down pat, I might return to indoor-pinhole.

 

[mysteryscribe]

good stay at it... The view camera is a lot of fun... Today I loaded one film holder went out and shot two negs it is more fun for me to figure out what to shoot and how to do it, than it is to just go burn film.

 

[Hertz van Rental]

You've been quite helpful in this little endeavor

I do my best

One final note:
Pre-flashing at around the 5% mark (max flash; max sensitisation) is capable of producing nucleation centres that have some stability - we're talking latent sub-image here... - and the emulsion can stay sensitised for several hours, maybe even as much as a day. Useful to do a batch in the darkroom before going out to shoot.
Lower levels of exposure do not have such a lasting effect and there is a cut-off point where the effect of flashing will wear off in a couple of minutes. There is also another where flashing won't have an effect at all - it regresses virtually as you do it. Unfortunately it is not possible to predict where these points are with any useful degree of accuracy.
Trial and error I'm afraid.

 

[mysteryscribe]

okay I just started a four hour exposure with a 25watt bulb on a paper negative. Now yall have me all curious. If, and that's a big word, I remember to close the shutter at the end of four hours, I'll post the results good bad or ugly. If i forget and am late it might be a good thing since four hours is the meter reading without any additional "low light" time.

 

[mysteryscribe]

as promised

So four hours still makes a good image... I think it is possibly the quality of the light as much as the quantity that causes the problem. Actually I always thought that. Still to make a paper negative by moonlight must be quite the trick, but a streetlight would do just fine I think.

 

[mysteryscribe]

There is a civil war reinactment next weekend near me. I feel a lot better about shooting paper negatives now than I would have a month ago. I still think I will shoot mostly film, but a few paper neg portraits might be in order.

 

[JamesD]

That image is great in color! I saw it on the other forum.

Some Civil War-esque portraiture would be great! I'd love to see it. Seems like this is a good medium for that type of image. Plus, since the reenactors are usually all about the period thing, they'll probably be more than willing to sit for you. That'd be a fascinating series, and I'd love to see it.

 

[mysteryscribe]

On a good day, with one of the full aperture cameras, the time would be just a few seconds. so yes I think it can be done easily. I am thinking I don't have enough film holders. I think I can use the 3x4 it has enough holders for this project. Of course I'll be developing it for a week which is good to. I can always use the push to work every day.