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  1. #1

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    Is Rollei Ortho 25 orthochromatic or not?

    Rollei ATO 2.1 seems clear enough. But when you read about Rollei Ortho 25, the literature says it is panchromatic sensitized. Is it ortho or not?

    And while we're at it, do you have to use a red safelight with a film like ATO 2.1 or other ortho films, or can you use a regular OC filter. I'd like to avoid buying a red filter if possible, but not sure if OC will be safe. I guess it depends on the spectral sensitivity of the specific film, but information on this stuff is scarce. I want to use ATO 2.1 for masking.

  2. #2
    Rick A's Avatar
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    I am as stumped as you about it being "panchromatic sensitized", as it is supposed to be orthochromatic.

    You cannot use an OC safelight filter with ortho film, needs a dark red filter in my experience.
    Rick A
    Argentum aevum

  3. #3

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    I've been doing some googling and it seems depending on the where you pull up the technical sheet sometimes it says panchromatic sensitized and sometimes it says orthochromatic sensitized. I'm starting to think when it says panchromatic it's just an error.

    Anyhow I'm still puzzled as to how it is different from ATO. It seems like ATO is probably higher contrast, but I'm not sure.

    In any case I guess I need to cave in and get a dark red filter for my safelight.

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    Rick A's Avatar
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    I finally gave in and added an OC safelight to my DR. I've only had red for over 40 some odd years. I still use the red most of the time as I mainly use Emaks and Varykon papers, and still have a supply of Forte in smaller sizes.
    Rick A
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  5. #5

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    The problem I will have is finding a 1A red for my old Kodak safelight. It takes the small 3 1/4" x 4 1/4" rectangles. I don't think Kodak even makes the 1A anymore. Maybe I could try to find a 1, but I don't understand how you can see anything with a 1 (not that I'll be able to find that one either).

  6. #6

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    Is a spectral sensitivity curve published for this film? That would answer the question as to whether it is ortho or pan.

    You have to use a red safelight.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  7. #7
    ath
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    The datashhet of the Rollei Ortho states it is sensitized up to 610nm.
    If it is similar to the Maco Ortho I used years ago you would need a very dim safelight, even with red.

    For a red safelight I recommend a small (!) red LED lamp. Cheap, lasts forever and very bright. Since the colour is generated by the semiconductors (red only) and not filtered from white fading is no problem.
    Regards,
    Andreas

  8. #8

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    If the film is sensitized to 610 nm, it is panchromatic. It is probably what we used to call Type A panchromatic, with poor red sensitivity (Type B was more or less normal, but still less red sensitive than many current films, and Type C had enhanced red sensitivity), but you need a wedge spectrogram for the film to be sure. Even with reduced red sensitivity, a safelight is an iffy thing. Most red LEDs emit significant light below 610 nm. Check the specifications for one that works around 660 or longer wavelengths. Then follow the rules for pan film - use it for a few seconds only after development is at least half complete.



 

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