Paper negatives

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Matt_Bigwood
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Paper negatives

Post by Matt_Bigwood » Tue Jan 10, 2012 6:36 pm Etc/GMT-1+01:00

I've bought a box of Kentmere paper and I'm planning on trying out my Thornton Pickard Junior Reflex with the paper in the film holders.

Can anyone give me a rough idea of the sensitivity of paper (I'll do some tests once I've got into the swing of it) - I seem to recall it was pretty low, 6 or 12 ASA?

michaelfinch
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Re: Paper negatives

Post by michaelfinch » Tue Jan 10, 2012 8:13 pm Etc/GMT-1+01:00

HI Matt. Some years since ~I used Kentmere for that purpose but I seem to remember 6ASA was a starting point. I was using their document art paper at the time. Good luck.

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Re: Paper negatives

Post by lostlandsuk » Tue Jan 10, 2012 9:31 pm Etc/GMT-1+01:00

Kentmere used to be one of the faster papers, but you are still in the extremely low ISO range - I would say about 6 is a good starting point - I would definitely ere on the side of caution and go for a longer exposure than you would think . . there's nothing worse than shouting at a tray full of developer when the blacks don't come up and then shouting again when they get too dense :lol:
I'd also recommend not including sky as that just results in more shouting :roll:
Phil

Matt_Bigwood
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Re: Paper negatives

Post by Matt_Bigwood » Tue Jan 10, 2012 11:12 pm Etc/GMT-1+01:00

Thanks for the advice - I'll report back when I've tried it.

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Re: Paper negatives

Post by banana_legs » Fri Jan 13, 2012 10:03 am Etc/GMT-1+01:00

Hi Matt,

Is it Kentmere graded or VC paper? For either case, it is best to pre-flash the paper first otherwise the dynamic range is really extreme (i.e. just a few stops and strong shadow/highlight clipping). All the following assumes you have pre-flashed the paper so that if an unexposed sheet is developed, there is just the very faintest grey fog. If it is graded paper (I use grade 2), shoot at an exposure equivalent to ISO 6 and then develop by inspection under a red light in diluted paper developer, pulling out the negative when it looks about right. If you use VC paper, a straight daylight exposure can be done at an equivalent of ISO20 but then you develop in full strength developer to completion. Thy dynamic range of the paper will be about 4 stops, so meter carefully! If you use VC paper through a yellow filter, use an equivalent exposure of ISO6 and again develop to completion. You will get about 8 stops range but the highlights will roll off non-linearly. When I have tried developing VC paper in dilute developer by inspection, I found that the highlight details would not develop evenly and I obtained a mottled effect, hence why I develop VC paper to completion.

Up to about 8 seconds and down to about 1/100th second exposure, the paper needs no reciprocity correction. As you go to more extreme exposures, the reciprocity does need to be accounted for. I did some calibration trials a while ago that resulted in a reciprocity correction equation that I have tested reliably up to 2 hour exposures. Below 1/100th second exposures the paper does not respond as quickly and needs more light than you expect, although the lightsource you need is verging on nuclear by that point.

Best regards,

Evan
More mad ramblings at http://blog.concretebanana.co.uk

Matt_Bigwood
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Re: Paper negatives

Post by Matt_Bigwood » Fri Jan 13, 2012 10:08 am Etc/GMT-1+01:00

Thanks Evan, that is very useful.

It is VC paper, so I will try it with a yellow filter. Did you pre-flash the paper under an enlarger for a second or so?

banana_legs
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Re: Paper negatives

Post by banana_legs » Fri Jan 13, 2012 10:49 am Etc/GMT-1+01:00

Hi Matt,

Yes an enlarger will be ideal. I have my system set so 4 seconds gives a good degree of flashing. It is simple to do a test; just put a strip of paper on the enlarger bed and uncover sections at 1 sec, 2 sec etc. and then develop (make sure half of the strip gets no light at all so that you have a base-white reference). What you want is the time where the paper is just showing a tiny shift in tone from the base white and therefore just a minimal level of fogging. I prefer to err on the side of caution and over-fog my paper slightly rather than under-fog.

Best regards,

Evan
More mad ramblings at http://blog.concretebanana.co.uk

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Re: Paper negatives

Post by Charles Twist » Fri Jan 13, 2012 10:25 pm Etc/GMT-1+01:00

Is that the same idea as what I see on Richard Cynan Jones Flickr page? If so, I am impressed and would like to learn more about your experience.
Regards,
Charles

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Re: Paper negatives

Post by banana_legs » Fri Jan 13, 2012 11:16 pm Etc/GMT-1+01:00

Hi Charles,

I have not been as adventurous as Richard Cynan Jones in that he appears to be coating his own paper in order to make proper Calotypes. I simply use normal commercial silver-gelatine printing paper (mainly B&W but do use RA4 for colour) in place of film in a film holder. For me it started as a cost saving exercise, however as paper negatives can be scanned on any ordinary non-film flat-bed scanner, they made my life much easier. Eventually as I got the hang of metering for the paper exposures, I rather started to like the look that you get with the non-linearities of the tonal range and the strong response to blue or blue/green light (i.e. like old orthochromatic film).

I tend to scan and then print digital negatives (rather than wax the paper) if I am going to print the picture as a cyanotype or carbon transfer etc, but for contact printing onto ordinary silver gelatine paper, you do not need to wax to make it more transparent at all; just use a bit longer exposure under a light source.

Using Ra4 colour paper is really challenging though as you often need an orange filter to help correct the colour cast, and then also find a scene which has a very narrow tonal range as the paper is very harsh and will clip the shadows and highlights very easily.

With the long exposure times of the paper negatives, it also makes using barrel mounted lenses (i.e. with no shutter) practical at wide apertures as the exposure can be made by removing the lens cap for a few seconds. I forgot to mention earlier that for long exposures, my reciprocity correction equation is:

Time_to_expose = tm+0.0078*tm^1.9

where tm is the time metered for the exposure. It is referenced to the exposure from my DSLR, with the time adjusted to an equivalent of ISO6 and then assumes development to completion for VC paper. Grade 2 paper seems to have a very similar reciprocity failure (up to a few minutes exposure anyway).

Best regards,

Evan
More mad ramblings at http://blog.concretebanana.co.uk

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