Latent image stability in modern films

Discussion in 'Film and Processing' started by oleksandrk, May 3, 2020.

  1. Being occasional/weekend shooter I am often in a situation where I just loaded the film, did some low number of shots, and then need to postpone shooting the same film for one or two weeks later. I try to not delay finishing the film for more than 1 week, but that comes along with a habit to find "something to shoot" merely for the sake of finishing it which I don't quite like. Processing film with just a half or less frames shot seems a waste too. Wondering how modern films do in latent image changes? Has anyone spotted some critical time threshold? I shoot mainly BW Ilford films, Velvia/Provia and Ektar. Based on my personal experience I assume that current films should be quite stable and allow some weeks to be unprocessed, but not several months. Would be interesting to hear other experiences and opinions.
  2. AJG


    When I shot color transparency film professionally I always finished up rolls of film quickly and got them processed as soon as I could to help to guarantee the most accurate color possible. B&W is much more forgiving, although Kodak used to recommend processing within 72 hours for optimal results. Currently, my B&W film usage is for personal projects rather than professional work and I usually wait until I have 4 rolls of film to process before I develop it. So far I haven't noticed any major problems from film getting developed 3-4 months after exposure. I am careful not to allow film to be stored under a lot of heat, but otherwise I'm not taking any special efforts to preserve it.
    bgelfand and oleksandrk like this.
  3. SCL


    I can't speak to modern color films, but I just developed a roll of 120 Arista which had sat in the camera 3 years between its 1st and last shots. There was no detectable difference in the negatives after processing. The camera was kept away from heat and light, which surely helped.
  4. Here is some information from the Kodak publication KODAK Color Films: The Differences Between Professional Films and Films for General Picture-Taking:

    All color films are manufactured in a similar manner. They are composed of several layers of complex emulsions made of different chemical compounds. Because these compounds tend to change slowly with time, all color films will age, beginning on the day that they are manufactured. As films age, their color balance and other characteristics may change slightly.

    To provide films that meet the needs of different kinds of photographers, Kodak allows for this aging process during manufacture. Kodak builds a small manufacturing bias into films for general picture-taking to compensate for changes produced by typical storage conditions and delays between purchase and processing.

    Regardless of the film type, you should use all films before the expiration date printed on the carton. You will also obtain the best quality when you process the film promptly after exposure.

    Kodak professional films are close to optimum color balance when they are manufactured and packaged. The film will remain near this balance if it's stored as recommended in the instructions or on the film carton and processed before the expiration date on the carton.

    Casual picture-takers usually buy one or two rolls of film at a time. One roll of film may remain in the camera at room temperature for several weeks or even months before processing.

    Under normal temperature conditions of 24°C (75°F) or lower, Kodak color films for general picture-taking do not require refrigeration. Storing them at room temperature allows the film to mature to its aim color balance and speed.
    But that doesn't say much about the latent image specifically. It does talk about film remaining in the camera for months though, and personally, in my experience, "professional" films don't really require such immediate processing as suggested in order to still obtain satisfactory results. Also worth noting is that B&W film is less sensitive to storage at higher temperatures than colour film.
  5. As to latent image shifting - most shifting occurs in the first 48 hours. After that period, this shift continues at a slowed pace.
    Amateur type films are more robust in that they can tolerate abuse. Most stability recommendation are based on the difficultly associated with the adjustment and calibration of automated printing at professional or photofinishing lab. It was tedious to keep printers in good color balance. Each batch of color film has a unique color balance. More modern printers are able to scan and analyze and thus correct color balance errors. In other words, much of the published data on color film and latent image shifting does not take into account digital printing techniques.
  6. As a kid the family camera may well have had two or three Christmas’s on a roll and that was common in many homes. I later learned that consumer grade films were optimized for that. So called pro grade films like Vericolor were meant to be refrigerated and processed soon after exposure. I generally used VPS and VPL and got them straight to the lab to avoid color shifts and that worked pretty well. B&W films though seem to last forever. I’ve had tri-x processed years after exposure and results were just fine.

    Rick H.
  7. Ilford Pan F+ has to be the worst film I've ever seen with regard to latent image keeping. I usually try to develop it within a day of shooting it. If you use it close to expiration(but develop promptly after exposure), you'll likely find strong negatives with barely visible edge markings.

    I went through a period from about 2010 to 2017 where I did not develop much of any B&W film. I didn't shoot much of it either, but I still shoot some and accumulated probably 30 rolls. I've been slowly working through it, and most of it is fine. The majority of it is Tri-X, but there's some HP5+, FP4+, and even Plus-X in there. I mostly develop with HC110, which some claims keeps fog down a bit, but I've not seen too much of an issue with fog when developing in D76.
  8. The one I mostly hear about is PanF+. I don't know what they do to it, though.
    Also, the edge printing is very light.

    I have had Tri-X to 30 years come out fine, though with a little age fogging.
    As well as I can tell, no latent image loss. I have known Verichrome Pan to
    about 50 or 60 years with plenty of latent image left. It is hard to know if some
    might have been lost.

    In ordinary use, and other than PanF+, I don't worry about a year or so.
    Keeping it at cool room temperature is probably best.
  9. You may have heard this story before...

    In the 1920s, three decades before Tenzing Norgay and Edmund Hillary reached the summit of Mount Everest, the British made several Everest expeditions, in an attempt to climb the mountain. During the 1924 expedition, George Mallory and Andrew Irvine were attempting to climb the mountain, and were last seen high on Everest making their final push for the summit. Nobody knows for sure if they made it or not, because they were never seen alive again. But they had a camera with them, and it is speculated that if the camera is ever found, it may contain a photo showing the climbers at the summit. Mallory's body was found in 1999, but no camera was found. That means Irvine must have had the camera, but his body remains undiscovered, for now.

    To quote Wikipedia: "Experts from Kodak have said that if a camera is ever found, there is some chance that its film could be developed to produce printable images if extraordinary measures are taken, and have provided guidance as to handling of such a camera and the film inside".

    More info archived here: Mallory Irvine
    and some pretty amazing documentary footage from the expedition here:
  10. Along with other properties, latent image keeping should be better at cooler temperatures.

    But it should also be dry. Frozen way below freezing might keep things dry enough, though
    one has to be careful when warming it up.

    I do hope he didn't use PanF+.

    I don't have any plans to keep any film that I shoot now for 30 or 40 or 50 years, though,
    so what matters more is what film was like years ago.
  11. What 'modern' films would those be?
    There's been no real breakthrough in film technology since T/Delta crystal technology was invented, and certainly no serious R&D money thrown at film for at least 20 years.

    The laws of physics haven't changed recently either, and electron dislocations in a crystal will naturally 'heal up' over time.

    So 'develop promptly' will still be seen on the instruction sheets of every current film. How long 'promptly' is exactly, is for the user to decide.
  12. Some details on how the chemistry works is here:

    US5246826A - Process of preparing photosensitive silver halide emulsions - Google Patents

    one of the important, but not so obvious, steps is ripening, much of which is
    described in that patent.

    The first step is mixing silver nitrate and potassium bromide in a gelatin solution,
    which precipitates out silver bromide, leaving potassium nitrate in solution.
    Later, excess ions are rinsed out, leaving mostly silver bromide, though some
    of the other ions will stay.

    Ripening is done with a silver halide solvent, that dissolves and
    recrystalizes silver bromide, changing the size and shape of the crystals.

    In the end, there will be some chemicals that are supposed to be there,
    and some that are just not completely removed. Some of those chemicals
    can make a grain developable, and cause fogging. Some can, as noted by Joe,
    undo the reaction that makes a grain developable.

    There is, then, a compromise between age fogging and latent image keeping.

    Both the ability of a grain to stay unfogged for many years, and then keep its latent
    image for many years are, in the end, pretty amazing.
  13. For sure.

    Is there a modern film? :rolleyes:

    Of course compared to my old favorite, Kodachrome 25, everything is "modern"

    I had some K25 that had been shot in the 80s to early 90s and finally processed it in the last year at Dwaynes. It had shifted to a greenish tone, but was surprisingly amenable to color correction.
    the first is a slide not corrected
    and the next slide with modest red correction
  14. Looks pretty nice!

    Maybe they should make a movie about this.
  15. Well, I didn't dig deeply into the molecular level of it, but don't we have those emulsions marked 'new', like Velvia, Acros II, "relaunched" Ektar, Portra "upgrades", films like AGFA Copex Rapid, Adox CMS, ILFORD introduced ORTHO Plus recently ... I recall some film manufacturers stating about lack of usual raw materials and adjusting "new" emulsions with available raw materials in mind. This is why I got the impression that when I buy "new" Velvia or Ektar, it may differ from that one from 90s in certain sense. It's not like I mean that they work according to some different laws of physics though, obviously :)
  16. I think the key word there is "marked".

    Does anyone really think that marginally viable companies like Kodak Alaris, Ilford, and the relaunched Agfa and Adox are going to hurt their bottom line with needless innovation? When their main audience is into nostalgia, and the last thing that's wanted is a radically new product.

    Like I said before. The laws of physics ain't changed much lately.
  17. As well as I remember, then TP (Technical Pan film) was discontinued, one reason was that they couldn't make
    it the same way anymore.

    When old films come back, like Ektachrome and TMZ, I am not sure if it is the same old recipe,
    or a new one.

    Also note, from some years ago, the difference between "Professional TMax" and "TMax professional".
  18. Having engineering background and experience of both large corporations and small startups, I would say that judging alone on company size or R&D investment figures doesn’t always match to successful innovation output.

    I agree that demand in analog market is nothing to compare with digital, but it doesn’t mean that there is no innovation to be made even in a small niche market.

    Here is a quote re. Velvia from Wikipedia:

    “The original Velvia (RVP) had been discontinued because of difficulties in obtaining some of the raw materials needed to make the emulsion. Fuji R&D created a new emulsion which substituted different materials in its manufacture yet retained the appearance of the classic Velvia.”

    Do I really care about “viability” or budget of Fuji R&D team? They managed to come up with a new emulsion and that’s awesome.

    Anyway, when I posted this topic I did not really mean to emphasize modernity of the films. It’s been great to see some insightful comments (as usual) :)
  19. In the US, the FTC has rules about claims that something is "new".

    I don't know how to find them, but I believe something can only be "new" for six months.
    It would seem that some part of it should be new, but that doesn't mean new physics.

    But if the box, and the ads, don't say "new", then it is probably fine (and not new).

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