Overexposing vs higher film speed

Discussion in 'Film and Processing' started by tom_fowler, Jan 28, 2014.

  1. Let's just say for the sake of argument that I am using 400 speed film. What is the difference between overexposing by 2 stops and telling the camera that I have 800 film speed and overexposing 2 stops. I know Jose Villa as well as Elizabeth Messina like to tell the camera it is a speed higher than what it is rated at to get their signature colors but what is the difference between that and just over exposing it by the same amount? Thanks!
     
  2. If you tell the camera it's ISO 800, that is under exposing by one stop. If you then over expose by two stops, the total change is over exposure by one stop.
     
  3. Overexpose ISO 400 film by 2 stop is like using it at ISO 100.
    Overexposing is like flooding it more. Brighter.
    One stop is one fold. Usually you have one pizza ok. You wanna overexpose by 2. That means you have 2 more pizzas (a total of 3). When ISO halves or doubles that means you are going down or up by (one) fold.
    OTOH if you tell you have ISO 800 when in fact you have 400. The film isn't gonna get enough light. A slow 400 car needs this much time 30 mins to get home. But you're saying you have a sport car instead 15 mins. Your station wagon isn't gonna get home by that time.
     
  4. When you rate a film at a higher film speed than it is you under expose the film.
    When you rate a film at a lower film speed than it is you over expose the film.

    What is the difference between overexposing by 2 stops and telling the camera that I have 800 film speed and overexposing 2 stops.​
    1 stop.
    400 ISO @ EI 800= -1 stop; over expose by 2 stops= 2-1=1 stop over exposed.
    ISO 400 @ EI 400 overexposed by 2 stops = 2 stops over exposed.
    Setting the meter to a different setting other than the film ISO is just an easy way to apply a specific amount of exposure change to the film in use.
     
  5. Tom: Are you referring positive color film (chromes/slides like Velvia)? With chromes, if you underexpose by raising the ASA to let's say 800 from 400, the automatic metering system will let in less light. That will cause the colors to saturate more than if you shoot at box speed.
    The alternative is leave the metering at box speed. Then reduce the opening of the aperture or increase the shutter speed. Either will reduce the amount of light and the colors will also saturate.
    I let other who use negative color film explain what similar action that occurs.
     
  6. ..a speed higher than what it is rated at to get their signature colors but what is the difference between that and just over exposing it by the same amount?​
    Without the confusion on how many stops (which others have answered): there is no difference indeed.
    The film I use mostly is ISO400, but I like it better when treated as ISO250. On one camera, I can set the ISO manually - my meter will give me readings for ISO250 film. The other filmbody I use is a modern entry-level SLR, that uses the DX code with no way to change it; the meter will give readings for ISO400, and so I overexpose by 2/3rd of a stop - end result: identical.
     
  7. Les +1, and it's not only true of 'modern' C41 films, but was historically true as well. Modern and Popular Photography in film days would regularly run tests showing more than 2 stops leeway for most color negative films.
     
  8. Hey thanks everyone I guess I didn't describe clearly what I was after. Let me try this again. This from an article I grabbed
    "José usually shoots Fujifilm Pro 400H and rates his film at ISO 200. This means he overexposes by one full stop per default. He then exposes for the shadows which results in another one to two stops. In total, he overexposes by at least two full stops. If you try that with a digital camera you will very likely blow out all of your images. With film, it adds contrast and saturation and, depending on the light, colors get a brighter pastel look."
    What is the difference between doing what is mentioned above and just shooting normal at 400 or over a stop at 400.
    I hope that clears it up better for you.
     
  9. Tom, regarding this excerpt from your quote, "In total, he overexposes by at least two full stops... With film, it adds contrast and saturation and, depending on the light, colors get a brighter pastel look."
    While working for a large chain outfit, I've done quite a lot of testing on pro color neg films, albeit of the lower speeds. In my experience, with studio portraiture, the part about extra contrast and saturation are just not true. We regularly had studios that accidentally overexposed by 3 and even 4 full f-stops, and after proper optical printing most people would not be able to tell the difference between those and rolls with "normal" exposure. I would expect 400H to behave in a similar manner, but have not actually tested it.
    I looked briefly at some on-line work of Jose Villa, and note that he does quite a lot of strongly backlit shots. This will give considerable lens flare, which will desaturate colors. But I don't think you can get his look with straight printing - I think the majority of it is from digital manipulation. Some of this might just be the result of a scanner that can't "see" through all that extra film density, but this would be a limitation of the equipment used rather than a real characteristic of the film.
     
  10. Fuji 400H film is color negative film - the brown film stuff like your usual mum / dad used. You can overexpose it. Might try that haha, many only overexpose by 1 stop. But if you did that with digital or slide film (projection film) you would get a very white washed photo as you know and mentioned. Color negative film have a lot more freedom to do this. Maybe it's why they used them with point and shoot cameras. When I use color negative film I just use auto metering ... don't bother with other methods. It might depend on the film or maybe my lab stuffed up, I try to do a bit more than one stop with Fuji ProS 160 but got color cast.
     
  11. If you try that with a digital camera you will very likely blow out all of your images. With film, it adds contrast and saturation and, depending on the light, colors get a brighter pastel look."​
    That is exactly why the Nikon Matrix metering system is great for digital and slide film but really bad for color negative film. With digital (and also slide film) you need to watch out for the high light. You want to give the highlight as much exposure as possible without blowing out and let the shadow falls where it might. With color negative film you expose for the shadow to insure adequate exposure in the shadow and let the highlight falls where it might.
     
  12. James G. Dainis

    James G. Dainis Moderator

    Here is an experiment I did with Fuji NPH 400:

    http://jdainis.com/film_expos.html

    Over or underexposing means that the printer analyzer will correct to achieve the correct exposure that one should have set in the first place.

    Overexposing to get more shadow detail means that mid tones and highlights are raised also. The entire print will be very light. The printer analyzer will darken down to get a good print exposure and the shadow details will be lost as they burn down to black again. To keep those shadow details on the print one would have to use selective dodging and burning. (Or Zone system development of the negative which is a whole other ball of wax.)
     
  13. I found that ilford hp5+ doesn't like overexposure. The negatives come back too dense.
     
  14. "José usually shoots Fujifilm Pro 400H and rates his film at ISO 200. This means he overexposes by one full stop per default. He then exposes for the shadows which results in another one to two stops. In total, he overexposes by at least two full stops. If you try that with a digital camera you will very likely blow out all of your images. With film, it adds contrast and saturation and, depending on the light, colors get a brighter pastel look."
    The writer of this article is deeply confused. “Overexposure” means giving more exposure than necessary to the point where image quality suffers. Overexposure does NOT automatically or necessarily result from setting any particular number for film speed or any particular metering technique. Furthermore, I defy anyone to tell me what a “brighter pastel look” is – brighter means more saturation, pastel means less saturation.
    ISO speeds indicate a film’s sensitivity to light when tested under defined laboratory conditions. The ISO speed is sometimes called the “box speed”. With color negative films, there is almost always a gain in color saturation by setting exposure on the basis of a speed number (called an “exposure index” or EI because it is not a true ISO speed) of half the box speed. Furthermore, with negative materials, it is normal practice (when using a separate handheld meter) to meter the shadows, since if you fail to record these at the moment of exposure you will get clear film and the shadow detail will be lost forever. You do NOT repeat NOT take the shadow meter reading and apply this directly to the camera as an exposure setting. Many people who use separate meters work with a thing called the zone system, which is worth studying in detail. In very very simple terms, zone 5 is the mid-point of a scale from 1 to 9 and is the mid-tone with 18% reflectance on which all metering systems are based. If you meter the deepest shadow which you wish to record, you will tend to place this reading at zone 3 or in simple terms set the camera to 2 stops less exposure. In practice, color negative films have tolerance to considerable overexposure (b+w films have some but less tolerance because they are more contrasty) but very little tolerance to underexposure – soon shadow detail and contrast are lost and pictures acquire an unpleasant green cast.
     
  15. David...brighter does not mean more saturation. It appears it is you who is confused.
     
  16. David...brighter does not mean more saturation. It appears it is you who is confused.
    I don't think so! "Brighter" does in fact not really mean anything - if it's used to mean "lighter", then of course this does not mean more saturation. if the meaning is "more contrasty", then it probably does. As far as I am concerned, there's no ambiguity about "pastel" - this means softer colors. Oldies like me are used to expressions like "bright negatives", meaning "more contrasty".
     
  17. James G. Dainis

    James G. Dainis Moderator

    Large format shooters who have spent a pleasant afternoon with friends looking at and comparing 4x5 and 8x10 negatives know what is meant by a "bright negative". A well made negative is a work of art and beautiful to behold.
     
  18. I still don't think anyone understands your question, but I do.
    Method One: Set the ASA on the camera lower than that of the film being used and meter normally, thus overexposing the film.
    Method Two: Set the ASA accurately to the film being used and overexpose your photo manually using a longer shutter speed or stoping up.
    Both should result in overexposed photos, but what's the difference?
    Am I right? I would also like to know if the methods produce different results. Both result in more light hitting the film which should produce the same results. I assume Method One is what's used more commonly because it allows you to use your in-camera meter the same as you normally would, making things a little simpler. If there is a difference in image quality between the two methods and someone can explain without waxing poetic, please help.
     
  19. James G. Dainis

    James G. Dainis Moderator

    400 ISO film the meter calls for normal exposure = f/8 @ 1/500

    Method 1 - 400 ISO film set at 100 ISO the meter calls for exposure of f/4 @ 1/500 or f/8 @ 1/125 (two stops overexposed)

    Method 2 - 400 ISO film set at 400 ISO the camera is manually set for exposure of f/4 @ 1/500 or f/8 @ 1/125 (two stops overexposed)

    There is no difference; the methods used do not produce different results. Method 1 and Method 2 both give f/4 @ 1/500 or f/8 @ 1/125 (two stops overexposed)


    I assume you have been away from photography for a long time and no longer understand the fundamentals. Film no longer has ASA ratings but uses ISO ratings..
     

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