A few basic questions about exposure

Discussion in 'Film and Processing' started by khiem_le|1, May 20, 2015.

  1. Hi everyone,
    I'm quite new to 35mm film and trying to learn and practice as much as I can, but the more I shoot the more confused I become. Please shed some lights and excuse me if the question(s) have been asked many times before.
    From what I know, neg print film has high/broad latitude, which allows a great deal of overexposure. People tend to overexposure a bit to preserve details of the shadow without worrying the highlight being burnt out like in digital. Knowing this I have been overexposing my shots by setting ISO on the body to 200 while using 400 film. About 70% of the times, the photos came out a bit washed out and seemed like it has a hazzy layer on top, which made the photo look quite unsaturated. Please have a look at this particular one:
    1. http://tinypic.com/r/5n7les/8
    It was shot under normal bright sunlight, at 35mm and f/1.4, in A-mode of a Nikon F100. Fuji Superia 400 film was used. Body was set to ISO 350 (or so). I notice the strong red colour of the flower wasn't very saturated in the photo and the whole photo just looks like there is a colour cast over it.
    This is another shot of the same roll:
    2. http://i58.tinypic.com/28akm6h.jpg
    It was a very bright day and it was shot at f/5 or so and also +2/3EV, so I can't understand why is still not clear and crisp.
    I suspect it is the lab's fault that the photos look like it has a magenta cast over it. Look at this shot: http://tinypic.com/r/2n3wbm/8 it can be easily seen that there is magenta case all o ver it.
    All those shots were scanned by a lab in a general supermarket here in Australia (BigW). It isnt' a professional lab or anything.
    So my final question really is: Where does that magenta cast come from? Is it from the lab? Is it because of the film stock I used? Is it because of the exposure that I used (in this case, almost +2/3ev to +1ev)? or is it because of the lens (which I highly doubt because the lens performs perfectly normal on my digital body)?
    Please shed some lights as I'm quite confused what have I done wrong.
    Thanks,
    Khiem
     
  2. SCL

    SCL

    A lot of exposure questions. If you can, get hold of a good book on exposure, something like "Light, Science & Magic" to help you understand some of the basic concepts. First and foremost, it doesn't make sense to begin exploring the outer limits of latitude until you have a firm grasp on what your film delivers at recommended settings, as well as metering characteristics of your camera. The F100 is an exceptionally good camera, and your lens is likewise excellent.....so they aren't at fault. Some films produce more saturated colors than others, as well exhibiting as higher sensitivity to certain parts of the visible spectrum...you can check out these characteristics on the mfr's websites, spec sheets sometimes included with the films, or a variety of photo forums discussing these issues. Cameras' metering systems look at the world as having varying intensities of light, and recommend or set exposure to adjust what is being metered as if it was 13-18% gray...this is where one begins to determine if exposure compensation is needed...ie reducing exposure to dark subjects, and increasing exposure to light subjects. Nikon's matrix metering does a terrific job of doing a lot of the thinking on this topic for you, but isn't always perfect. Lastly, color casts in printing are often due to labs failing to calibrate equipment, over-using the same chemicals, or just plain lack of training of technicians. Since you already are familiar with digital, presumably you are also familiar with post processing and what can be achieved there; well, the same is true with film, except, unless you do your own processing, you are turning over all decisions to somebody else without giving them specific guidance photo-by-photo. This is a lot to swallow at one gulp. If you can scan your shots and play around with them in a post-processing product on your PC, like Photoshop or Lightroom, you can answer many of your quesions and determine how to best proceed in the future.
     
  3. Are you setting the ISO to 200 AND giving it plus 2/3 compensation? If so you are doubly overexposing. I personally believe in sticking to the manufactures ISO rating, but others may differ.

    The flower shot, at F/1.4 at 400 ISO in bright sun, well the sunny 16 rule would suggest a shutter speed of 1/64000 sec., unless I've got my sums badly wrong. Perhaps the F100 can't attain a fast enough speed to expose it correctly. If you really want F1.4 for a very shallow depth of field, you would need to use an ND filter or shoot in much duller conditions. An aperture of say F/11 might give you better results, with more depth of field but the background still reasonably out of focus. And the lens may not be at its best at maximum aperture.

    The other shots have a very wide range of tones, for example if the car is correctly exposed, the road and sky would be overexposed. No matter how you set the exposure these scenes are difficult to render correctly. The matrix metering on these cameras is very clever but it makes it harder for the photographer to decide whether to use exposure compensation than, for example, when using spot or centre weighted metering.

    As to the magenta cast, it doesn't look so bad on my monitor. Surely it's not the lens or exposure, probably processing or scanning.
     
  4. I've always struggled, trying to get decent colour out of colour negative films. These were decades of saved films, scanning them myself. Currently I only shoot a little black and white, scan it myself. Unfortunately, scanners are hard to come by now. Some thoughts:
    1. Shoot (the color negative film) at the rated ISO.
    2. Try some slide film.
    3. Shoot black and white.
    4. Try getting your own scanner.
    I think you want to persevere with film, and that's worthy, still: consider switching to digital?
     
  5. Find a better lab, or scan them yourself. Your exposures look fine and your methodology sounds okay.
    But it's getting more difficult to find a competent minilab now. The film processing is usually automated and goof proof, as long as the film and chemicals are fresh. But it's harder now to find competent scanning and printing. Color correction requires manual input, and the few remaining minilabs I see locally don't bother with training anymore.
     
  6. All three of these sample shots look mostly like crappy scans. They basically need the contrast boosted a bit. You are never going to be able to judge your work taking your film to the grocery store. Either find a professional lab or do it yourself. As Medel says, try slide film -- the film you shoot is the finished product, so what you shoot is what you get and the variables of printing or scanning are eliminated.

    As for the broad latitude of negative film, that does not mean that you are supposed to routinely overexpose it. It means that when you have a wide range of brightness in a scene, that it can handle the brighter parts if you expose for the shadows. And it means that it will usually be OK if you overexpose by accident. The the film at the box speed -- 400 at 400. Try to meter off something with average reflectance -- ideally a grey card, but green grass in the summer of the back of your hand year-round. If in doubt, err on the overexposure side. But do not set your meter at 200 for 400 speed film, 100 for 200, etc.
     
  7. James G. Dainis

    James G. Dainis Moderator

    Your films may be properly exposed but how can you tell that from the prints? The printing exposures could be all over the place. I once took a number pf photos of surfers. When I got the prints back it looked like the exposures were all over the place. Some photos were light, some were dark, some were okay. I had shot all the photos with the camera on the same manual setting based on an incident light meter reading. The light never changed. All the negatives themselves were of equal density, not some light and some dark. So what happened?

    In shots where there was lot of white water surf, the printer analyzer would think, "This is too light I had better darken down" and I would get an incorrect dark print. If there was a lot of dark blue water the analyzer would incorrectly lighten up the photo. A printer analyzer can be "fooled" just the same as a camera light meter by too many lights or darks in a scene/negative frame.

    The only way to correctly judge exposure is to learn to read the negatives. When I get my photos back the first thing I do is pull the negatives out and look at them. A less dense frame between two other good frames will mean I underexposed that frame, a denser frame will mean I overexposed that frame. Only after that will I take the photos out and look at them.
     
  8. Fuji color films seem to have a magenta cast built into them. Try a roll at box speed.
     
  9. Are you sure you're not confusing in your reading black & White film with color negative film? Many photographers will do tests of B&W film to determine an exposure index different from the stated ISO. It is pretty common with B&W film to cut the Iso in half.
    It is not common to do so with color negative film. The processing of color negative film is standardized and changing the process is usually only done for some special effect.
    While some photographers find it helpful to adjust their exposure index slightly from the box speed with color film, it is rarely a full stop.
    You might try a simple shoot around. Pick a subject and expose a series of negatives of that subject. Start at box speed and make exposures giving 1/4 stop more exposure down to one stop exposure. Go back to box speed and give 1/4 stop less exposure up to one stop. do this for several different scenes under different lighting--bright sunlight, flat lighting, indoor, long exposure. There should be one exposure setting which gives you the best exposure for your working method. Albeit, given the different lighting on the scene, your best Exposure Index may be different in bright light to flat light.
    When the lab prints the negatives, have them print each negative the same--without compensation. If you have a negative with bad exposure, the lab will automatically try to adjust the print to cover the bad exposure.
     
  10. Is the lens by any chance an AiS 35mm f/1.4 lens? The first photo looks rather typical of that lens' behaviour wide open, plus I'd say it is a bit overexposed (ISO400 film, bright daylight and f/1.4 do not mix well).
    If you want to do controlled tests, I'd also recommend to use a lens as this one at around f/4-f/8, where it performs best optically, to reduce the number of variables in play.
     
  11. Although as you said if you use f/1.4 in sunny day with ISO 400 it would surely be overexposed as the camera do not have a high enough shutter speed. But looking at your pictures I can't see any sign of overexposure. I am sure all of your pictures can be scanned darker.
     
  12. Thanks everyone for your opinions and advices. From most of the comments, it looks like the lab I used was the one who caused the magenta cast over the photos.
    From a few rolls that I got back from this Grocery store lab, It does look like shots that are done indoor/under shade area/lack of direct light always get that magenta cast? Is that a typical thing that can happen? With shots that are shot under bright direct sunlight, the magenta cast almost disappeared. This is an example shot: http://i62.tinypic.com/1zqek9i.jpg
    Also, like some of the members said, using wide open (at f/1.4) on a sunny day is probably a not good idea and that also might have caused the flower shot to be a lot over exposed.
    Is the lens by any chance an AiS 35mm f/1.4 lens? The first photo looks rather typical of that lens' behaviour wide open, plus I'd say it is a bit overexposed (ISO400 film, bright daylight and f/1.4 do not mix well).​
    It's a Sigma 35 f/1.4 lens, but I guess it'd be similar to the Nikon AI-s.
     
  13. Although as you said if you use f/1.4 in sunny day with ISO 400 it would surely be overexposed as the camera do not have a high enough shutter speed. But looking at your pictures I can't see any sign of overexposure. I am sure all of your pictures can be scanned darker.​
    I think this is what happened too.
    Also, I'm a bit confused about the process of developing and scanning film. So people seem to agree on the fact that each lab will give a dramatically different scanning result, due to the setting they use with their scanners, staff, training etc. However, is the very first step of the whole process (develop films with chemicals) standardised? i.e is developing film the same process in terms of quality, everywhere? Reason is I've been thinking about getting myself a scanner, but if the film developing process is also another factor to consider, it'd be a bit more difficult to eliminate all the variables.
     
  14. AJG

    AJG

    Color film processing shouldn't be a variable, but it is, especially now that demand for it is a fraction of what it was 15 or 20 years ago. Chemistry needs to be replenished and replaced often, and when it isn't the results will suffer. But if labs replace their chemistry often in the face of low demand, then their profits disappear. It's worth it to find a good lab and stick with it, and send your friends there also so that they will have enough volume to do good work at an affordable price.
     
  15. I think you're wasting your time shooting color negative film. About the only thing you have control of is the exposure. The developing and printing is often it is done poorly so you can't really judge how you're doing.
    Shoot some slide film if you want to learn about exposure.
     
  16. Developing the film is standard and back in the old days most lab would do a very good job on this step. Today due to low demand it becomes much more difficult to keep the process stable so it's better to find a lab with sufficient work to keep the quality control daily. A test strip is also expensive but if you run 1 test strip and then process 100 rolls or so is not expensive but if you run a test strip and then you only have a couple of rolls a day it's expensive. But if you don't check your process daily and make correction if needed the process could run out of control.
    Making the scan or the print you're at the judgement of the operator or the machine. And even good operators may not be able to do it to your liking.
     
  17. "... it looks like the lab I used was the one who caused the magenta cast over the photos."​
    Yup.
    "From a few rolls that I got back from this Grocery store lab, It does look like shots that are done indoor/under shade area/lack of direct light always get that magenta cast? Is that a typical thing that can happen? "​
    Nope. Fuji color negative film, even their low priced Superia and Superia X-tra, are very good. Any competent minilab should be able to deliver neutral color. If anything I find Fuji color negative film tends toward over-saturated greens in foliage. But it should never be magenta, unless the mixed lighting is impossible to overcome - such as a mixture of metal halide, tungsten, fluorescent and halogen in the same shot.
    But if the predominant lighting is a single color temperature the results should not have a noticeable color cast. That's almost always due to incompetent printing/scanning.
     
  18. +1 for Stephen Lewis. If the OP really wants to get a handle on exposure, than a good book as recommended, even a class where you go through it systematically will enable you to answer most all of your exposure questions. Really, starting with basic exposure is best instead of starting from messing with ISO settings and compensation etc. First method you could learn is the Sunny 16 rule. Than learn how the meter works etc. Sunny 16 is important though because its really the basics of core exposures and once you learn that (it doesn't take long nor is it particularly hard). You can start doing more advanced things with various ways of using your meter and in-camera adjustments. Just a suggestion.
     
  19. Your pictures look over exposed which makes sense because you arbitrarily changed the rating of the film doubling the exposure.
    Some recommendations.
    First off always use film that has not expired. (Was yours expired?). Second, shoot box speed and then bracket 1/2 stops + and - if the subject isn't moving, like landscapes. You have to learn to walk before you can run. You're just learning and should start with normal settings and shoot in a standard way.
    Note that bracketing will also give you something to compare and will also more likely provide a properly exposed picture in one of them if you made a mistake in calculating exposure. Try shooting slide film also. It will give you exposures of what you shoot and show them easily. Sometimes, with negative film, you really don't know what you have. Have a lab make contact prints so you can compare easily.
    Get a good book on exposure and how to shoot film. Good luck.
     
  20. Nope. Fuji color negative film, even their low priced Superia and Superia X-tra, are very good. Any competent minilab should be able to deliver neutral color. If anything I find Fuji color negative film tends toward over-saturated greens in foliage. But it should never be magenta, unless the mixed lighting is impossible to overcome - such as a mixture of metal halide, tungsten, fluorescent and halogen in the same shot.​
    You are right. I tried shooting again with a whole mix of different indoor lighting and the result does not look that bad at all. I used a different lab thought. This is what it looks like:
    • http://i61.tinypic.com/2s5y8up.jpg
    • http://i58.tinypic.com/709yqu.jpg
    ...First off always use film that has not expired. (Was yours expired?)...​
    Yea Alan, the film I used for those shots expired a few months ago. I did realise that when I took it out and loaded to the camera, and I thought a few months after expiry would not make much different. I think this contributed more or less to this issue. Thanks for the advice re bracketing. Since starting shooting film, I haven't really thought of using bracketing but it is actually a very good idea. Used it all the time before on my digital body to shoot HDR.
    Re Exposure books: do you have any recommendations? I find it a bit harder to find books or material regarding exposure for shooting films. I've shot with my fullframe digital body for quite some years now, but when it comes to shooting film, getting the spot-on exposure is a bit harder than I thought. Even when using auto meter.
    Thanks everyone for your inputs. I've shot another roll and tried getting it scanned at a different lab and am quite please with the results. Therefore it's quite conclusive that the grocery store lab did quite a bad job, probably at developing the film as well.
    • http://i59.tinypic.com/11awvio.jpg
    • http://i60.tinypic.com/fxurrt.jpg
     
  21. Your follow up photos look much better. Exposure and color look good.
    Regarding metering and exposure technique, using color negative film shouldn't be too much different from your D700, which has good dynamic range. If anything the color negative film will be a bit more forgiving of overexposure, although scanning may require multiple passes to wring out difficult highlight detail. But rating a good color negative film at half of the box ISO shouldn't present any difficulties to a decent lab or good home scanner. Many folks will rate a color negative film around 1/3 to 1/2 EV more exposure than the box ISO, to minimize any risk of underexposure. But it's pretty forgiving stuff, not nearly as critical as color slide films and some older digital cameras that had mediocre dynamic range.
     
  22. Thanks Lex.
    This is another shot done at box speed and scanned at a proper lab:
    http://i61.tinypic.com/2eevivs.jpg
     
  23. Much better!
     
  24. Check the internet for books. The last two picture look good. Good luck and have fun with film.
     
  25. Thanks and I am so glad I've been received a lot of constructive feedback and comments from this community. Really appreciate it!
     
  26. A few months expired should be fine.
    But if the film gets too warm, even way before expiration, the results can be bad.
    Kept cold, even frozen, it will last years past expiration.
    An automatic full stop overexposure it too much. I sometimes round off to the nearest whole stop, toward over exposure for negative films, underexposure for reversal films, so maybe a half stop over.
    But it all depends on printing. One result of the large latitude for negative films is that you have to be twice as good at printing exposure. That is, it is much easier to get the exposure wrong at print time. Also, the color is more sensitive at print time, so it is usual for printers to do autoexposure and auto color balance. And both of those can be confused by background.
     

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