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What went wrong?

My whole roll is too light or too dark, even though I followed the meter

Camera

What you're seeing

Every frame on the roll is thin (underexposed) or dense (overexposed) by about the same amount, even though the camera's meter said the exposure was right.

Check this first

Check this first

Look at the edge markings on the negative. If the frame numbers and film name are strong and normal, development was fine and the problem is exposure in the camera.

Likely causes, most common first

  1. 01

    Wrong film speed set, or DX coding read wrongly

    Common
    How to tell
    The error is the same on every frame and is a whole number of stops (for example a 400 film set to 100 is two stops overexposed). Often after switching film types.
    Test it
    Check the ISO dial or display against the film box. On DX cameras, check what speed the camera shows for this cassette; some set non-DX film to ISO 100, others keep the last roll's speed.
    The fix
    Set the speed for each new roll and check the camera's display after loading.

    Sources Nikon (scan: butkus.org), Nikon FM2 (FM2N) instruction manual (specifications); Kyocera / Contax; scan by Butkus (orphancameras.com), Contax T3 instruction manual (specifications page, p.62); Minolta (scan: butkus.org), Minolta Maxxum 7 instruction manual; Nikon (scan: butkus.org), Nikon FM3A instruction manual (specifications)

  2. 02

    Wrong or failing battery, especially in cameras made for 1.35 V mercury cells

    Common
    How to tell
    An older camera designed for a mercury cell (for example the Minolta SR-T 101, which takes a 1.35 V PX-625) gives consistently wrong readings with a 1.5 V alkaline or silver-oxide substitute. A worn-out battery can also stop the meter needle moving.
    Test it
    Take readings of a bright sky and a dim room with the camera and with a meter you trust (or a phone meter app). If they differ by more than half a stop, especially by different amounts in bright and dim light, the battery or meter is the problem.
    The fix
    Use a voltage-matched substitute, an adapter, or have the meter recalibrated. Otherwise offset the ISO setting by the error you measured.

    Sources F. de Gruijter (hosted by M. Butkus), The mercury cell problem and its solutions; Minolta (scan: butkus.org), Minolta SR-T 101 instruction manual (specifications); Photoethnography, Classic camera batteries; Asahi/Pentax (scan: butkus.org), Pentax K1000 operating manual (specifications)

  3. 03

    Meter fault

    Occasional
    How to tell
    The error varies with the light, or the meter needle sticks or jumps. Ilford lists a faulty meter or incorrect readings as a cause of both dense and thin negatives.
    Test it
    Compare the camera's readings with a separate meter across several scenes.
    The fix
    Have the meter repaired, or use a separate hand-held meter.

    Source Ilford Photo (Harman Technology), Common Processing Problems

  4. 04

    Shutter running slow or fast

    Occasional
    How to tell
    Frames at some speeds are fine while others are too dense or too thin. Slow speeds that run long often overexpose; sticky fast speeds can underexpose.
    Test it
    Shoot an evenly lit scene at the same exposure value using different speed and aperture pairs (for example 1/60 at f/11 and 1/500 at f/4). Develop: all frames should match.
    The fix
    Get the shutter serviced, or avoid the speeds that are wrong.

    Sources Andrew Davidhazy, Rochester Institute of Technology, Calibrating your shutters; Ilford Photo (Harman Technology), Common Processing Problems

Avoiding it next time

  • Check the ISO setting every time you load.
  • Check the meter against another meter when you get an older camera.

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