A positive form negative

Discussion in 'Darkroom Developing and Printing' started by piterengel, Aug 29, 2008.

  1. piterengel

    piterengel Guest

    Hi everybody. I need for a certain work to obtain some positives from
    negatives. I can't treat all film with positive method, because a part
    of photos must remain negatives. I have a Contax Auto PC Bellow with
    slide duplicator, and a RTS II camera. Photos are taken using an
    Ilford Delta 100 film, developed in ID11. I want to use the same film
    for positives. My questions are:

    - can I find somewhere a manual for PC Bellows?
    - Is it better to use natural light of TTL flash light to make

    Thanks all for the help.

    piterengel, Aug 29, 2008
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  2. piterengel

    Peter Irwin Guest

    The film to use for making positives on 35mm film is
    Eastman 5302 Fine Grain Release Positive. I bought
    some from Kodak in Toronto a few years ago for something
    like $CAN 17 for a 100 foot roll. Kodak Motion Imaging
    will probably still be willing to sell you a roll, it
    is also listed for sale at electron microscope suppliers
    because it is used by some models of electron microscopes
    as well as by the motion picture industry.

    The speed of 5302 is somewhere around 3 ASA, but this
    depends a bit on development and how much blue and violet
    are in the light source. Develop in Dektol 1:1 for 5 minutes.
    You can adjust contrast a little by playing around with
    different developers. The film looks like white plastic.
    It can be handled fairly freely under any safelight for
    B&W enlarging paper. You should have no trouble bulk loading
    it into 135 cartridges by hand.

    Peter Irwin, Aug 31, 2008
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  3. piterengel

    Peter Irwin Guest

    I hadn't known that. The Jan 31 2008 Price Change Bulletin
    would seem to show 1000 feet rolls as a minimum quantity.
    That may not be a complete disaster though. 5302 is one
    of the cheapest films made, so I think that 1000 foot roll
    might be around $120.

    It also may still be possible to buy an 100 foot roll from
    a microscope specialty store for around $20. I bought 100 feet
    of 5360 from Ted Pella, since Kodak had a minimum order of 1000 feet
    of 5360.

    The PDF for 5302 is at:

    Peter Irwin, Aug 31, 2008
  4. piterengel

    piterengel Guest

    After a bit of time I'm back with few news.
    I've tried to obtain positive from negative as follow.


    I've used Ilford Delta 100 film developer in Perceptol full strength
    fo 15 mins. Subjects were macro images of iron dust modelled with a
    magnet. Camera: Contax RTS II, lens Zeiss Planar 60 f/2.8 Macro.
    Negatives are good, reach of details, a little bit dark but this is
    not a problem.


    Equipment: Contax auto bellows with slice copier tool, RTS II mounted
    and Planar 50 f/1.7 as lens. I've extended bellows for 50 mm to obtain
    1:1 macro ratio. The lens was set on f/16, the minimum aperture
    available. I've used a TTL flash as light source (I've tried with a
    high power incandescend light source but results were worst).

    Film: Efke 25 developed in Rodinal 1+100, prebath of 1 min in water,
    than developer for 18 mins. This was a test film, for the final work I
    want to use Kodak Tech Pan filam (yes, I've few of them in my

    Problems: I've noted, as said, taht it is better to work with flash
    light; but the most important problem is that the center of the
    pictire is in focus and edges are not. This is a very big problem for
    me. I've not the bellows instructions manual but I don't think I'm
    doing something wrong. Before using my precious Kodak TP film I hope
    somebody can help me.

    Thanks all

    piterengel, Oct 20, 2008
  5. piterengel

    piterengel Guest

    Mr. Knoppow, as any other time you're right. The problem was lens.
    I've adapted Planar 60 Macro to slide copier, working at f/22. Results
    are very good. In the meanwhile I've ordered on eBay from England an
    adapter ring from M42 to Contax to be able to mount enlarger lens on
    bellows. Till now it is not arrived but surely I'll try with this too.
    Thanks bay now
    piterengel, Oct 23, 2008
  6. This may work. But it is unduly complex.

    I would second Richard's suggestion of contact-printing the film. With a
    sufficiently dim light, even standard 25ASA film will work to make the
    positives. Simply cut lengths of the unexposed film to match the lengths
    of the cut strips of developed negative film, align them carefully, and
    place them in a standard glass-front, foam or rubber-backed contact
    printer, or, if you do not have a contact printing frame, use a heavy
    sheet of glass (1/4" or thicker) on top of the two pieces of film, on
    top of a clean, black surface.

    It will take a few tries to calibrate exposure but you can use normal
    development times and will achieve excelent results. And there will be
    no focus or sharpness problems -- guaranteed.

    Slide copiers exist really only to deal with the annoyance of copying
    already cut and mounted slides, which are too thick to be contact
    printed as I describe above with good results.
    Thor Lancelot Simon, Oct 24, 2008
  7. piterengel

    piterengel Guest

    Today it is arrived the adapter ring I've described above. So I'll try
    with 50 mm enlarger lens first, then with contact print too. In this
    last acse, do you have an approximate idea on time of exposure? I
    think to place the column at least 10 in high with completely close
    diafragm of lens (f/22). so how long could be the exposition? or can I
    try to use an external exposimeter to determine this?
    piterengel, Oct 24, 2008
  8. That would be, of course, "the exposure for a good print
    of the same size as the lighted area cast by the enlarger
    set to cover the contact frame" -- the exposure with the
    enlarger column at the same height, basically. I'm sure
    Richard knows this but I got it wrong the first time I
    tried this process so I thought I should elucidate.
    This is what I have always found simplest.
    Another option which occurs to me is to use Kodalith. Is it
    still sold in 35mm roll film? For the longest time, it was,
    but under a different (and strange) product name. It does not
    have a pigmented base, and if developed in a very dilute
    developer (HC110 dilution F works; POTA would probably work
    better) will in fact give negatives of slightly higher than
    standard contrast. It's also *very* slow, and can be handled
    under a dim red safelight. Perhaps it is almost ideal for this
    use. The disadvantage is that more work will be needed to
    calibrate exposure and development since Kodak's tables won't
    be helpful.

    What I did last time I needed nice snappy slides from copied
    small format negatives was develop normally and then intensify
    with very strong selenium toner (1:3). This gives a color
    change, which is not ideal, and is wasteful of the somewhat
    expensive toner, but I was in a hurry and it got the job done
    with the materials I had on hand, and I didn't have to recalibrate
    my development system for some oddball developer like Dektol 1:10.

    Chromium intensifier, if you can still get it, would probably work
    Thor Lancelot Simon, Oct 24, 2008
  9. The 35mm Kodalith I remember was "Kodak Ektagraphic HC". It's been
    discontinued and I am not sure *any* Kodalith remains in production.

    Thor Lancelot Simon, Oct 28, 2008
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