Double exposure

Discussion in 'Film and Processing' started by diegobuono, Jan 3, 2020.

  1. Hi All,
    I have a question regarding the double exposure technique:
    I want to photograph two subject that have a very different background; in every subject the background is the sky but in one exposure is a normal daytime sky (normal to bright sky), in the other exposure is the night sky (total black, only the subject is illuminated). Does the final picture will show an "in between" sky or the black of the night sky will win over the daytime sky and I will end up with a total black background?
    I also purposedly overexposed the picture with the daytime sky, in the hope to lighten a bit the black sky of the second picture, but I am not sure of the result I will obtain.
    Thank you in advance.

    Diego
     
  2. Assuming you shoot negative film: It can't differntiate between being not exposed at all and exposed (properly) to entirely black, so you'll see only the daytime sky (in the just sky areas. Other stuff will be overlayed by it).
     
  3. William Michael

    William Michael Moderator Staff Member

    Double exposure technique:

    I suggest that you do not purposely overexpose the daytime scene.

    If this is a task just to "see how it goes" then make both exposures "correctly", (i.e. as per what would be 'correct' would be if each were only a single photo).

    If this an important task, then I suggest that it would be better to BRACKET the double exposures.

    Obviously, if you are waiting several hours from day to night, or visa-versa, to make the second shot of the double exposure, you either will need take a few days to get these brackets made, one each day - OR - you need to have an excellent technique in making the first exposures and then reloading / the film in a black bag or darkroom, accurately for the second exposures to align to the first exposures.

    A guide for the brackets-

    Frame 1 - both scenes exposed 'correctly' (i.e. as per what 'correct' would be if each were only a single photo.)
    Frame 2 - First scene exposed -1 Stop, second scene exposed 'correctly'.
    Frame 3 - First scene exposed -2 Stops, second scene exposed 'correctly'.
    Frame 4 - First scene exposed 'correctly', second scene exposed -1 Stop.
    Frame 5 - First scene exposed 'correctly', second scene exposed -2 Stop.

    The above will accommodate a good to very good outcome for most double exposure scenarios, both for B&W and Colour NEGATIVE Film, however, if this task is really important then continue:

    Frame 6 - First scene exposed +1 Stop, second scene exposed 'correctly'.
    Frame 7 - First scene exposed +1 Stop, second scene exposed -1Stop.
    Frame 8 - Second scene exposed +1 Stop, first scene exposed 'correctly'.
    Frame 9 - Second scene exposed +1 Stop, first scene exposed -1Stop.

    ***

    Another technique you might consider, especially if you are shooting Positive Film, is to make a range of brackets for each scene and then Sandwich the resultant Negs/Trans, in the Enlarger.

    WW
     
    Last edited: Jan 3, 2020
  4. Thank you all.
    I tried different exposure with different exposure (from normal to ecerxposed) and using two different film magazine (Hasselblad).
    Unfortunatly the two location are 60km apart and the two exposure have to be made 4 hours apart. Not simple at all. It took me several attempt during several days.
    Let's hope something good is on the film. I should ask before next time ;-)
     
  5. James G. Dainis

    James G. Dainis Moderator

    If you look at the negative of the night sky you will see that the film part of the sky is clear except for base color. It will have no more effect than if you laid a sheet of glass on top for the double exposure print..
     
  6. "Photography" means "drawing with light". You are recording light. If there is no light, there is nothing to record.

    Imagine you take a perfectly exposed photo of your cat. Now put your camera in a changing bag, and re-expose that frame for 30 seconds. What happens? Nothing. There is no light to record. It is not the case that the darkness from the inside of the changing bag wins over the exposure of your cat.

    Similarly, the darkness (lack of light) of the night sky will not somehow override or black out your first exposure of daytime sky. Of course that's a simplification - the night sky is not totally lacking in light.
     
  7. Ok it is perfectly clear and to be honest I don't know how I could put such a silly question (and done such a mistske in overexposing 2 stop and more to compensate the dark 2nd exposure) after more than 20 years of film using :-(
     
  8. Silent Street

    Silent Street Silent Street Photography AUS

    A much simpler method is to simply multiply the film speed (which is in 0.3 stops) by the number of multiple exposures, with no other adjustment required. This has been my method for 40+ years!!

    Example, 3 exposures: film speed of 50 * 3 = EI125 —> This is the new speed setting to put on the ISO dial.
    IMMEDIATELY AFTER THE LAST EXPOSURE, REMEMBER TO RESET THE ISO DIAL TO THE BASE ISO OF THE FILM (IN THIS EXAMPLE, ISO 50).

    Additionally, unless you have some specific abstract intention in mind, any time you are involved with multiple exposure, the camera should be mounted on a tripod and not moved at all from one exposure to the next, save for any desired / intentional adjustment to focus, f/length or aperture.

    Slide film can be used this way too, however you will need to make generally narrow adjustments to cater for its shorter latitude (tolerance for over- and -underexposure) compared to the more generous chacteristics of negative film, be it colour or B&W.
     
  9. 50 × 3 = 150. I would suggest that is closer to 160 than 125. Or do I misunderstand your method?
     
  10. Silent Street

    Silent Street Silent Street Photography AUS

    Either/both. Depends on what film you are using; I spoke from the viewpoint of transparency film rather than negative, where an arbitrary EI can be applied without undue worry to the end result.

    With transparency film, my long-term practice is to err on the side of underexposure, as highlights are unrecoverable if overexposed. That said, establishing the correct EI for sequential multiple exposures is one of experimentation and analysis (= experience!), again, especially critical with transparency film. I still make errors with MEX, especially when light is changing or fading (twilight, for instance). Flat to overcast light across all exposures will benefit from a slightly higher multiple EI; bright light over multiple exposures goes the other way, pulling back the exposure, though flaring is likely; it's not really a good idea to stack many multiple exposure frames shot in very bright light unless there is some overriding artistic/abstract effect desired.
     
  11. Since this thread has bubbled to the surface again:
    Double, or multiple exposures, aren't quite as simple as just dividing the total exposure by the number of superimposed images.

    A black background or black portion of a subject effectively has no exposure. Therefore any subsequent superimposition over that black area needs a full exposure to register correctly.

    The above example of 'pasting' someone's face onto a doll requires not only a black background for the person's face, but also a black area where the doll's head should be to take the second image properly. And each image would require the full and correct exposure for both the doll's body and the person's face. Giving half the exposure to each would just result in an underexposed composite.

    Besides, if the end result is going to be scanned, as I suspect most film images end up these days, then it's far easier to do the superimposition using an image editor!
     
    Last edited: Feb 5, 2020
    stuart_pratt likes this.

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