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  1. #1
    Petzi's Avatar
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    "Digital" RA-4 paper and optical exposure

    The manufacturers of RA-4 photo paper now offer papers that are optimised for exposure in a digital printer, i.e. through laser or LED.

    I understand that the digital papers are formulated to give maximum density with a very short exposure. I heard of cases where Dmax of conventional papers could not be reached with the very short exposure times in digital printers, which can be a small fraction of a second at high intensity. I assume that this is due to reciprocity failure.

    Now I wonder, if one uses these papers that are made for digital, do they have any disadvantages when you expose them conventionally, i.e. at multiple seconds exposure? If the manufacturer improved reciprocity behavior at very short exposure times, does that mean the papers still work well at regular times? Is it simply an improvement of one characteristic while maintaining other qualities of the paper?

    Characteristic curves are now given for "laser exposure" or ".04 s exposure" in data sheets. But no curve for reciprocity behaviour is given.
    Last edited by Petzi; 05-08-2006 at 07:34 PM. Click to view previous post history.

  2. #2
    Photo Engineer's Avatar
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    There is a recent thread regarding this. You may want to look it up.

    The answer is that all of today's color papers will work with either type of exposure.

    PE

  3. #3
    Petzi's Avatar
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    I have not been able to retrieve substantial information from the archives other than "Yeah it seems to work". I would like some more background information.

    I have studied the data sheets for "optical" and "digital" papers, and the characteristic curves look quite different. I suspect in some cases though that they are the same paper. But I am not sure. The differences might be due to the effect of different exposure times.

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    When I was working at an optical minilab we made the switch from fuji CA to fuji CA type II(both the consumer stuff and type II meaning "optimised for digital exposure units). Once calibrated to the new paper, results are identical by my eyes, my lab tech's eyes and our customer's eyes.

  5. #5
    Samuel B's Avatar
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    I have read on a minilab forum that the Agfa digital paper was not really suitable for optical labs, that it suffered from unusual colour shifts when expsosed in an optical machine. Not really an issue now that Agfa is gone. However I think most papers are suitable for both optical and digital exposure.
    Film's not dead, it's just got a negative image.

  6. #6
    Photo Engineer's Avatar
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    I assure you that due to improved reciprocity characteristics, both the Fuji and Kodak ppaers are fine with either type of exposure.

    PE

  7. #7

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    Hi petzi,
    Still having some doubts ?
    The guys I can order from were not so sure about wether it was possible or not. They said something about me taking an risk when buying a for digital use optimized paper. On the other hand there are some reasons to believe it must be possible with good results.
    One is that when reading the original product pdf, on in this case, the ilfoflex digital paper, one will find that the paper is intented for both ways of exposing. Also, a seller should not be taken to objective. On one hand he wants to sell, on the other hand he does not want any argueing afterwards about money backs etc.
    I also was wondering, if using digital machines for exposing an done wants to make a really large print at lets say f16, and the negative is thick, what exposure time will you get? Maybe the same as with a small print, with f5.6 and a thin negative... the optical way

    Anyway, I am not to concerned about wether digital papers are suitable or not, I think it is possible....

    game

  8. #8
    Petzi's Avatar
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    I just like to get to the bottom of things.

    Last week I saw an Agfa printer in action, that made about 7 prints per second from 35mm film. It is fed with 550m rolls of photo paper. When taking into account the time needed to advance paper and film, that results in some pretty short exposure times for fully optical printing...

  9. #9
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    Petzi, about 20 years ago I was in the Melbourne Kodak photo finishing lab watching machines processing 1,000' rolls of 35mm colour film, which was going through enormous machines making colour prints.

    These machines were printing so fast that the strobes sounded like machine guns firing. If the paper that was in use then, could handle those short exposures, whilst at the same time be used in my darkroom with exposures measured in minutes, I wouldn't be worried.

    Just use the stuff.

    Mick.

  10. #10
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    I have used 'Digital' RA4 under the enlarger and it works as the non digital stuff. Konica's (it may now be gone from the market) appears to be identical to Fuji CA. i've used it digitally and straight under digital it uses the same profile as CA and looks identical. Kodak's old digital II and III (I think that was the designation) appeared to be a match for Supra -- both types are out of production or atleast rebadged.

    *

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