Does photo paper have an ISO rating?

Discussion in 'Pinhole Photography' started by BetterSense, Jan 11, 2009.

  1. BetterSense

    BetterSense Member

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    I just made a 8x10 pinhole camera out of foamcore last night because I was bored. Since I found out you can contact print with paper, I figured I would buy some 8x10 paper since it's pretty cheap, because I don't know but I figure 8x10 film is expensive.

    I found pinhole exposure calculators online at mrpinhole.com but they depend on the ISO of the film you use. But the paper I was going to buy (Illford multigrade IV from amazon.com) doesn't have an ISO rating. It seems like it would make sense that it would.

    Anyway, is that a decent paper? I heard that I could buy laser-cut pinholes online, is that true? How important in a pinhole camera is it that the paper be held perfectly flat? Since focus shouldn't be an issue I figure it should be pretty forgiving.
     
  2. Pinholemaster

    Pinholemaster Member

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    Micro-drill pinholes: http://www.pinholeresource.com/shop...page=flypage.tpl&product_id=89&category_id=16

    All photographic paper has a ISO rating: http://www.ilfordphoto.com/Webfiles/2006130200232336.pdf

    The best way to determine how sensitive the paper is that you are using is through testing.

    Paper flatness all depends on what YOU want as a result. In paint can pinhole cameras, the film or paper is curved along the wall of the can. In a traditional pinhole camera, the paper or film is held flat. If you want it wavy, try it out.
     
  3. BetterSense

    BetterSense Member

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    That Illford paper data sheet was unclear to me because they seemed to use weird units like P500. I was wondering if it had a simple ISO number that I could use as if it was film. Like ISO 8. There's a bunch of stuff there about filters.
     
  4. Photo Engineer

    Photo Engineer Subscriber

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    There is a paper ISO rating and a film ISO rating. They are not related.

    Ilford MGIV paper has an ISO of about 25. It is not orthochromatic though and has two contrasts at two wavelengths. Graded papers often can be used more effectively than MG papers.

    PE
     
  5. jnanian

    jnanian Advertiser Advertiser

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    you can get laser cut pinholes from pinholebilly on eBoo,
    or through pinholeresource.com ...

    have fun!

    john
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    A company in the US makes metal slides with micro holes cut in them at varying diameters. They are rather inexpensive and come packed in neat little boxes for handy use. Tom Miller, an expert pinhole photographer, uses these for his cameras. I'm surprised that he has not chimed in here. He gives workshops at the Photographers Formulary.

    PE
     
  7. AgX

    AgX Member

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    PE,

    can you relate ISO Paper speed to ISO Film speed?

    In scientific reports ASA Film speeds are given to photographic papers ranging from 1/100 to 10 ASA Film.
     
  8. Joe VanCleave

    Joe VanCleave Member

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    Bettersense: First, welcome to the interesting world of pinhole. You may find it taking more and more of your photographic time. Follow your passions.

    As for film flatness, it not only is not an issue, but there are some unique things you can do with pinhole regarding purposely unflat film, such as anamorphic cameras (film wrapped in a cylinder, the pinhole at the end of the cylinder); curved film planes, etc.

    There is a slight "defocusing" effect when using a pinhole camera for extremely closeup subjects, an example being when the subject matter is the same distance as the focal length of the camera, in which case the image blur at the film plane caused strictly by geometric effects is double the diameter of the pinhole itself. When I intend on shooting dioramas or other close-in subjects, I use a camera with a purposely smaller-than-"ideal" pinhole diameter.

    The quality of the pinhole is at least as important as getting the "ideal" diameter. Actually, there is no "ideal" size from an image aesthetic perspective; it's all good. Smooth, thin-walled pinholes are important, whether hand or commercially made, as they make for smoother tones.

    Paper negatives: I've shot paper negatives for the last 15 years, both in glass-lensed and pinhole cameras. The biggest problem I found was high contrast in bright light. The problem with MG paper is that the high-contrast part of the emulsion is activated by the UV/blue light, which predominates in daylight. Therefore, I've chosen to use grade 2 paper; I like RC finish for negatives, as it sits flatter during contact printing, so I use Arista's RC grade 2.

    Secondly, I find with pinhole cameras that you can lose shadow details in daylight when trying to keep the highlights from blowing away, so I've taken to preflashing the paper in the darkroom prior to loading in camera. I use a faint, 7.5w type S-11 bulb, suspended about 30" above the work surface in a metal soup can enclosure with a 3mm aperture; typical preflash times for Arista grade 2 are 10 seconds. This yields a faint, gray tone to an otherwise unexposed negative. It helps to bring up shadow details. I actually preflash all my paper negatives, even when used in glass-lensed cameras.

    Good luck and have fun.

    ~Joe
     
  9. keithwms

    keithwms Member

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    Bettersense, I agree with most of the above and here is what I would recommend with just about any ilford b&w paper. First of all, preflash the paper. Assume a paper sensitivity of ~ISO 3 and flash it ~3 stops below what you will expose it for your shot. The sensitivity wil be boosted to ~ISO 5-10 or even higher, and you will also get the benefit of a bit less contrast. Next, expose it rated at ~ISO 10 and develop by inspection in slightly diluter-than-normal developer. Maybe two bath dev, just play around.

    Oh, and take two or more shots of everything, remember paper is cheap! So make backups so that you can expeirment a bit with development. Also remember that the warmth of your fingertips can be used during development to boost blacks in some selective areas, so you can fight back contrast a bit that way too.


    Remember that the paper is mostly blue/edge green sensitive.

    Just enjoy and experiment!
     
  10. Photo Engineer

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    Yes, you can relate ISO Paper speed to ISO Film speed.

    You expose a series of paper negatives until one is properly exposed and one that will scan properly to form a good reversal image. At that point, you have the ISO. Then you compare that ISO (In-camera) to the paper ISO and begin constructing a conversion table.

    OTOH, you have to remember that this is not a true emulsion ISO, as the paper picks up speed from back reflections.

    An alternative method, which is much harder, is to do exposures on a spectrosensitometer and then integrate the area under the curve.

    I have used both methods. I find therefore that Ilford MGIV paper is close to a true ISO of 25, all things considered such as the high average contrast and the back reflection. I have posted some of that here before.

    PE
     
  11. Kimberly Anderson

    Kimberly Anderson Member

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    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.
     
  12. Photo Engineer

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    Michael;

    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.

    PE
     

    Attached Files:

  13. BetterSense

    BetterSense Member

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    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?
     
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  15. Kimberly Anderson

    Kimberly Anderson Member

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    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.

    EDIT:

    I have not shot my Gretag color checker with my paper negs. That will be the next step for sure!


     
  16. jnanian

    jnanian Advertiser Advertiser

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    look into photowarehouse.biz
    they have inexpensive paper ...
    and they are an advertiser here

    have fun!

    john
     
  17. jnanian

    jnanian Advertiser Advertiser

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    hi michael

    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?

    thanks!
    john
     
  18. Photo Engineer

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    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.

    PE
     
    Last edited by a moderator: Jan 12, 2009
  19. jnanian

    jnanian Advertiser Advertiser

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    thanks for the clarification PE!

    john
     
  20. Photo Engineer

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    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.

    PE
     
  21. keithwms

    keithwms Member

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    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.
     
  22. Photo Engineer

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    Keith;

    You brought up an important point. You have overexposed to fight contrast. Well, if you overexpose and either under develop to get lower contrast or develop normally, you will be talking about at least 2 stops which is about ISO 6 or thereabouts. This will reduce the contrast nicely, but it will not center a tonal scale at normal development.

    All of my photos include the MacBeth Checker and have the neutral scale centered with Dmin on one side and Dmax on the other, and they were given normal development, no under or over, and no flash.

    I think that all of this is important. I am trying to get at the full tonal range. To actually do this with a paper, I suggest a grade 0 or grade 1 graded paper.

    As for spectral sensitivity, the Ilford MGIV and most graded papers today have a short green sensitizer that is much shorter than I expected. It peaks at about 520 nm as opposed to 560 - 580 for a "normal" green sensitizer. This gives things much more than blue or dark green no detail or image at all and seems to further increase contrast demanding more overexposure to the eye.

    Take a look at my images above and see what I mean about centering the density values on the scale.

    PE
     
  23. Kimberly Anderson

    Kimberly Anderson Member

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    Just shot my Gretag chart under strobes. Processed normally for print paper, Sprint 1:9 for 3 minutes. Looks pretty good. I don't know what would account for the discrepancies...perhaps PE is using a different developer and/or method that would account for his ISO being so radically higher than mine and what others have experienced. Very weird. I'll get it out of the wash soon...
     
  24. Photo Engineer

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    See my previous posts Michael which include the entire process and exposure methodology. If I used 3 minutes in Dektol or Liquidol, I think that the negatives would be seriously overdeveloped and dark.

    PE
     
  25. Kimberly Anderson

    Kimberly Anderson Member

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    Dektol 1:3 for 60 seconds is your normal development time? This is where you are arriving at your ISO of 25?

    Dektol 1:2 for 2 minutes seems like normal print paper development time for me in my own darkroom work. The Sprint paper developer I am using is nearly identical to Dektol.

    Maybe that's where the difference is coming in. I'm going to scan these negatives right now...
     
  26. Photo Engineer

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    If you consider for a minute that what you suggest would darken my paper negatives a bit, that would then mean that they are even faster than ISO 25 at my current exposure.

    What do you think about that?

    PE