what if I choose different ASA on my Film camera then is the film role...

Discussion in 'Film and Processing' started by lieven_van_meulder|1, Sep 21, 2018.

  1. hi

    I'm basically a very beginner in film photography?

    question: what if I choose different ASA on my Film camera then is the film role?



    I own a film camera where you can change the ASA you want to use on the camera itself.
    So if you use a 3200 ASA film , you should change the ASA setting on the camera accordingly.

    But what if i use a 4OO asa film and i put the camera setting on 3200 ?
    Or what if i use a 3200 asa film and i put the cameras asa on 400?

    1 . what happens then?
    2. what are further developing possibilities in these cases?

    Thx
    Lieven
     
  2. paul ron

    paul ron NYC

    if your camera is using the asa setting for its metering and auto exposure, you will be either over or under exposing the film. if you catch the error before processing, yiu can compensate development accordingly and maybe save the shots. but realize this dev compensation will cause grain or color shifts you may not be happy with.
     
  3. Dustin McAmera

    Dustin McAmera Yorkshire, mostly on film.

    First, as Paul said already, on some film cameras, the ASA/ISO setting is just a film-speed reminder. Setting the speed only has an effect on exposure if the camera has a lightmeter.

    Setting the camera to rate the film above its 'box speed', you're telling the camera to under-expose the film. This is quite a traditional thing to do, as long as you also over-develop the film afterwards to compensate. This is called 'pushing' the film. With black-and-white film, there are some developers that are specially suitable for this, and they come with extra developing times for push-processing. Kodak HC110 is one of my favorites, and it allows push-processing.
    Pushing ISO 400 black-and-white film to 800 or even 1600 is very normal. It used to be the only way to shoot in low light without flash. You get a particular look to the pictures, too; pushing will increase the grain. Some people like the effect. Tri-X or HP5 push very well up to ISO 1600; 3200 is asking a bit much, but you would get pictures.

    If you're not doing your own developing, it may be hard to find a lab that will do push-processing for you. They are likely to charge extra for the non-standard process, and they may not be willing to push three stops (400 to 3200).

    With colour film (colour negative; I don't know if you can push colour slide film) the developer kits I use give times for push-processing, and I've tried it. I have pushed ISO 400 film to 1250 (so a third of a stop less than 1600). It worked well, and I think I could have gone to 1600.

    (here's an example: Wet lower Briggate )

    Going the other way (exposing the film at 400 when its box speed is 800, say) is called 'pulling' the film. You just leave it a shorter time in the developer. I have never done that, and I don't really see when you'd need to, unless you had the opportunity for a great photo, but you wanted a wide aperture, and all you had with you was really fast film. Most people would use a ND filter instead. I guess there may also be interesting results in terms of grain or colour; I don't know. Fast film is typically more expensive. I have never seen times for pull-processing supplied by the film makers; there may be times at digitaltruth.
     
    Last edited: Sep 21, 2018
    lieven_van_meulder|1 likes this.
  4. hi Dustin and Paul,
    thx for your help.

    -
    I really am not sure about this.
    I can say i have a Canon AE1-program camera. Inside there's no such thing as a meter that would indicate over or under exposure. What there is indeed , is a "diafragma indication" given my shutter speed that i choose.

    So i assume there must be something of a meter??

    -
    To understand better what you say. What you mean by 'box speed'??
    thx
     
  5. Dustin McAmera

    Dustin McAmera Yorkshire, mostly on film.

    Yes; your AE-1 Program (nice camera!) has a built-in meter. That's what controls the aperture when you do auto-exposure. I only mentioned it because I had a conversation on Flickr once, with someone who was using a really old camera with no meter and all-manual exposure, and couldn't understand why setting the film speed on the reminder dial didn't change anything.

    'Box speed' just means the speed printed on the box the film came in; the speed the manufacturers give for the film.
     
    lieven_van_meulder|1 likes this.
  6. Yes there is push processing for E6 films.

    As for black and white, usually one or two stops.

    There are (used to be) some E6 films designed to be pushed.

    Unlike black and white films, E6 has one development time for all films.
    But higher speed films naturally need longer development, and so the higher speed E6 films are designed for pushing.
     
  7. hi Dustin McAmera,


    To understand you better.
    What is actually going on in the camera, if you Set the camera to rate the film above its 'box speed
    i think i don't understand well.
     
  8. AJG

    AJG

    If you set the camera's meter to a higher ASA than the film actually is and follow the meter's recommended exposure then there will not be enough light to properly expose the film. Negatives will then be too light and there will not be enough detail to make good prints or any prints at all. Unlike digital cameras where you can set a different ISO and gain sensitivity in low light conditions, film is manufactured to have a specific level of light sensitivity. It is possible to push process film and apparently gain sensitivity, but what you really get with push processing is higher contrast, which can certainly be helpful under low light conditions, but there is no free lunch--grain will also increase.
     
    lieven_van_meulder|1 likes this.
  9. Dustin McAmera

    Dustin McAmera Yorkshire, mostly on film.

    In the camera, there is a light sensor, or perhaps more than one. The meter in the Canon A-series cameras measures over most of the picture frame, but giving extra weight to the centre.
    Let's say you want to take pictures on a fairly cloudy day. When you press the shutter button, the camera reads the output from the meter. I don't know, but I guess this is a voltage value: it doesn't matter for this conversation. This voltage is one input to a fairly simple calculation that the camera's microprocessor does to get the correct aperture. The other inputs are the shutter speed and the film speed. Again, I don't know, but I guess the dials for these might be adjusting variable resistors.
    If you move the shutter speed one stop faster (say, from 1/125 to 1/250), and take the same picture again, the camera will move the aperture one stop wider to compensate; say, from f/8 to f/5.6. If you move the shutter speed slower, it will close the aperture down.
    If you change the film speed one stop higher (say from ISO 400 to ISO 800), the camera will close down the aperture one stop to compensate.
    So, if your film is really ISO 400 film, but you set the film speed dial to 800, the camera will expose the film correctly for ISO 800, which is one stop underexposed for ISO 400. If you process the film normally, your pictures will all be a bit dark. But if you leave the film a little longer in the developer, you can corret for that (more or less).

    But you don't need to think about any of this to push film. They put microprocessors in the cameras to let us forget this stuff. If you have ISO 400 film, and you want to use it in really bad light, all you do is set the film speed dial to 800 or 1600, and pretend the film is that fast, and trust the camera. But first you need to make sure you can get the push-processing done.
     
  10. "question: what if I choose different ASA on my Film camera then is the film role?"

    - Simple. You'll get over or under exposure.

    So called 'push' processing does next-to-nothing to the speed of a film. All it does is increase contrast, and that can be done in scanning.

    The true speed of a film is baked-in during manufacture, and without going to extremes like mercury-vapour hypersensitisation, there's not a lot you can do to alter it. Certainly not just setting silly numbers on the camera ISO wheel.

    Buy the speed of film you need.
     
    stuart_pratt, Moving On and Jochen like this.
  11. I just did exactly that! I thought I had one film in the camera but actually had another. I exposed a 25 ASA film as 400. As people have said above, you can often change developers and/or develop in the tank for longer than you would normally to bring out an image, but there are always sacrifices to make (more grain, higher contrast, etc.) and pushing film is generally limited to only 1 or 2 stops. Also developers can only develop what is on the film and if there isn't much there, nothing you can do in development will turn up much of an image (or any at all). In my case with 4 times time development time in a stronger developer I managed to get a scannable image in a few frames that I had unintentionally overexposed a little. But most of the roll was lost.

    In the past, my yearbook group in high school had us shoot TriX (rated at 400) at 1200. There was a procedure by which we overdeveloped it (push processed it) and created usable images, though they were grainy. There used to be some color films which thrived on push processing such as Fuji MS100/1000 which I found to be very good even at 1000. But in general some films push better than others and generally even if there is a recommended push processing for the film you used, it won't come out exactly like it would have had you done it right. Sometimes in the old days SOME picture was better than none so we pushed Tri-X.

    it's pretty great these days on digitals to just turn up the ISO for a few pictures. But in the old days the "iso control" was really in the hands of the manufacturer of the film. When you "messed" with it by putting the wrong ISO on your in camera meter, you were mostly on your own, using the film in a way not recommended by the manufacturer (except for films like MS100/1000 which were meant to be pushed).

    I'd do some googling online for push processing black and white and see what "recommended" pushes are feasible (even with side effects). It might be fun to try. Tri-X is a good one because it got pushed a lot over its life. It will allow you to see how the film changes when underexposed and overdeveloped.
     
  12. I find it somewhat ironic that film is now reaching its highest level of utility at the very point where it is threatened with extinction. I guess the best horse-drawn buggies were built in the early years of the 20th c.

    First, look up ISO film speed (link) and compare to EI (exposure index, e.g., link). The first based on the manufacturer's testing of the optimum for the film. The second is an arbitrary exposure according to the photographer's wish or choice.

    I mention this because Ilford XP2 Super (a black and white film that is processed in C41 chemistry) has the flexibility to allow really vast differences in exposure for usable results without any alteration of the developing process.
     
  13. To sum up all of these responses:

    When you're just learning to shoot film, the best thing you can do is match what you set on the camera to what's printed on the box/roll. There are specific situations where you might change this(I underexpose certain slide films in certain cameras because I like how it renders them, while I often overexpose certain color films for better color) but don't think about that now.

    Overexposing B&W film and reducing development time decreases contrast-something that's not always entirely bad. With that said, I'd rather just go straight to a lower contrast film like FP4+ than shoot Tri-X at EI 200 or 125, but it's something that can be done in a pinch. I'm not above shooting FP4+ at EI 64 or so, though, either, especially in a high-contrast scene on sheet film. This is often "flying by the seat of my pants" though and it has taken some trial and error for me to get that particular exposure to work-usually I do D76 1:3 for around 8 minutes.
     
  14. On digital cameras, the ISO knob sets the sensitivity of the sensor, and also the meter to set the exposure.
    There is usually a setting to increase or decrease the exposure as read by the meter, usually in 1/3 stop units, plus or minus two or so stops.

    For film cameras, the film has a designed-in sensitivity. You can stretch that a little with development changes.
    The ISO knob controls the meter, and there might also be a way to add or subtract without changing the meter setting.

    The effect won't be exactly the same, but you might play with the exposure compensating dial on a digital camera, set it up or down, one or two stops, and see how it changes the result. It is mostly useful when the meter isn't metering what you want it to. One that I have found where it is especially needed is in sunset pictures, where getting the background sky and land right is important.

    So, there are two reasons to set the meter to other than the ISO value on the box. (ASA if you have an old box.) One is that you want to push or pull the film, possibly with changes in development. (Kodak recommends the same development for Tri-X and TMax-400 for EI of 400 and 800.)

    Technically, ISO is a property of the film, usually in combination with a developer. If you use a different exposure index, you should call that EI and not ISO.

    Continuing, the second reason to change the meter setting is for light conditions that the meter gets wrong.
    Traditional (that is, more than about 40 or so years ago) meters average (arithmetic mean) over the whole scene. Better would be geometric mean over the scene, and modern meters do close to that. Otherwise, spot meters that concentrate on the center, where hopefully the more important parts of the scene are, also usually works well. But sometimes you know better, and change the meter EI accordingly.

    For beginners, best to set according to the box value, in combination with the developer you plan to use.
     
  15. If I can be overly pedantic, it's technically not correct to refer to "ISO 400 film." Per the ISO standards, both the ASA and DIN speed should be given-that means that Kodak, for example, is ASA 400 but is ISO 400/27º(DIN is a logarithmic scale, and a change of 1 represents 1/3 stop of change in sensitivity).

    For that reason(I want to be correct, and rarely remember or feel like looking up DIN speeds), and because I'm stubborn, I always refer to film box speeds as "ASA." Of course, as you said, the ASA is a property of the film, so if I'm exposing at something other than the box speed I always refer to that as its "EI." I only use ISO to refer to digital camera sensitivities.

    There again, though, that's me being pedantic about it. I'm not going to jump all over someone for calling a film "ISO 400" or for saying that they "exposed Tri-X at ISO 800." I, however, would say "Tri-X, an ASA 400 film, exposed at E.I. 800."
     
  16. OK, but I'm holding a box of Ektar 100 right now and it states "ISO 100" and nothing else.
    (personally I still refer to speeds as ASA)
     
  17. ISO - ASA = a distinction without a difference
     
  18. Vincent Peri

    Vincent Peri Metairie, LA

    Hmm... a tempest in a
    developing tank...
    [​IMG]
     
    Moving On likes this.
  19. Hey I used to live in Metairie. My mom lived there and I still have a cousin there. My mom's family was all in New Orleans or thereabouts originally. Used to go to Lakeside Camera.
     
  20. Technically, I suppose, I agree with you, and if I lived in Germany, I might be especially interested in the difference.

    But then again, cameras that I use have the ISO scale marked with the number on the left. Maybe there is menu option to change it.

    Rereading my post, I never mentioned specific ISO values. I did mention T-Max 400, which is not called TMax 27, or TMax 400/27.

    http://wwwuk.kodak.com/global/en/professional/support/techPubs/f4016/f4016.pdf

    I use ASA when referring to old film, old cameras, or old light meters. (I have enough of each of those.)

    I try to, though might sometimes miss, use EI in the appropriate case.
     

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