This is very interesting.
I would bow to the superior knowledge of Photo Engineer almost every day of the week...except today. I have been shooting paper negatives for about 4 months now, and have had my students shooting 4x5 paper negs as well. We are using Ilford MGIV fiber paper and have done exhaustive testing. Everything we're finding is that it needs to be rated at ISO 3. We're developing in Sprint paper developer diluted 1:18. We have not done any pre-flashing. That'll be the next step. These are being produced for contact printing if that matters.
I shot mine in a speed graphic outdoors and metered with a Seconic spot meter. The exposure times were in the range of 1/25th and 1/50th of a second. Could it be that we are seeing a speed / reciprocity failure problem. I'll warrant that you are using very very long exposures, a situation for which the paper is not designed, any more than it is for my rather short exposures.
IDK, but the speed I have been using is ISO 25 and my reference in the same camera is /was Polaroid at ISO 100 along with Portra VC at 100. The pictures included a MacBeth color checker as reference.
Oh, I also cut small sheets and placed them in an old empty Polaroid pack and exposed them in my RZ67 with the autoprism set at ISO 25. Same results. The one sitting next to me right now was exposed at f8 1/50". Scans of the negative and print are attached.
Do you have a suggestion as to what kind of paper and where to get it? The prices I have been seeing have been something like 50 cents a sheet, which is cheap, but perhaps it could be had cheaper?
remember paper is cheap!
Out of curiosity, I just shot a few sheets of 8x10 in the studio, shot at 1/200th of a second with strobes. I compensated for bellows factor, and both shots are within 1/2 stop of each other. They're in the wash...I'll shoot some digi-snaps of them and post when they're dry.
Again...I would bow to your wisdom, and I wondered if I was seeing different things than you were. I have shot paper in the studio and outdoors, and regardless of the length of exposure it always seems to end up at about ISO 3.
I have not shot my Gretag color checker with my paper negs. That will be the next step for sure!
Originally Posted by Photo Engineer
look into photowarehouse.biz
Originally Posted by BetterSense
they have inexpensive paper ...
and they are an advertiser here
Originally Posted by Michael Slade
i have tested papers over the years.
at one point i had a chart of maybe 10-15 papers
that i ran iso tests on, from azo to oriental ... rc and fb, graded and vc
i too have never been able to get my paper to agree that it is
iso 25 ... maybe PE is using a bluer light than we were using ..
i have only used daylight and strobes .. and my numbers
are similar to yours ..
PE what lighting are you using, something that is more blue-rich?
The photo above was shot outdoors in full daylight.
The Speed Graphic shots were taken with a vintage lens from the 40s, and the RZ shots were taken with a UV filter over the lens. That is about all I can say. My references taken with the same camera on Portra and other films and the Polaroids came out just fine too at their proper ISO ratings.
If there is something wrong or skewed about my results, I'll be happy to have it pointed out to me. And, BTW, this is how I test my ISO 40 Ortho emulsion. Same cameras, meter and method. I have had 3 workshops with groups of students verify this ISO # with their own cameras - not mine, and also several private workshops that have gotten the same ISO 40 value for my home made emulsion here using my cameras.
My ISO 40 emulsion coated on paper is about ISO 100, another correct value as you gain about 1 stop when you coat a film emulsion on paper base due to back reflection. So, my film emulsion on paper is about 2 stops faster than the Ilford MGIV.
When used on-easel, my film emulsion is about 2 stops faster (or more) than Ilford which is a further point of reference.
I use Dektol 1:3 or Liquidol 1:9 for processing at 68 deg F for 1 minute.
thanks for the clarification PE!
BTW guys, after reflection, I remembered how often we used to go onto the roof of the Kodak Research Labs B-59 or out the side door into the managers parking lot and shoot "girly pics" of a lab tech holding a MacBeth color checker. We used to use this same method for verifying the speed of our films under real world conditions.
The charts we shot at EK were read with a densitometer and placed on the aim curve to see where they fell in density vs ISO rating to insure or double check our calculations.
No, I suspect reciprocity perhaps in these experiments. IDK. Paper is generally not intended for being used at much below 1/2" or much about about 90" or thereabouts. I would think that we are all outside of this range in one way or another. IDK.
I expose and process within about 10 minutes as well so there is no Latent Image Keeping.
Do bear in mind that because of the reduced sensitivity spectrum of the paper (usually uv/ blue / blue-green) the ISO numbers have to be taken with a grain of salt. You have to think about the sensitivity spectrum of your meter and also the output of your light source.
Anyway, I also tend to think of most papers as having ISOs around 3-5 or so. Indeed there may be reciprocity failure at play: when I shoot to paper, I am typically using a pinhole or stopping down quite a bit to overcome registry/flatness concerns, while also tending to overexpose habitually, because I want to fight contrast (probably best to push one's exposure a bit to an extremity of the tone curve if contrast is a big concern- that was my thinking as I recall it, which may or may not be correct). And finally, I know I will be developing by inspection and can snatch quickly enough to get what I want.
Ron mentions latent imaging keeping, I hadn't thought much about that. Actually I tend to develop quite a few hours or even a day after shooting, so maybe it is an issue, IDK. My finding, as I recall, was that the benefits of flashing were there many days after flashing, so I was just ignoring latent image stability. I also never put thought into this, I just played around some time back and concluded that it was cool. Now I have a big stash of old bromide paper and maybe I will play with it again.
About the expense of paper, well, I think you can buy large rolls of paper, and even panchromatic ra4 paper like the ilford rc digital stuff or hyper seagull.
Seems to me that one tremendous reason to shoot to paper is the ease of touchup... on the backside. Just with a pencil and eraser. I haven't made much use of that but it's got to be easier than touching up ordinary negs.
P.S. Maybe it is possible to hyper some fiber paper? Anybody tried? What would you do, treat it in hydrogen at 100F or so? This question probably reveals my complete ignorance of how different paper and film are at the chemical level.