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I recently purchased a Sigma SA-9 and two SA-7n's. These are SLR (film) cameras. With the kit lens that came with it, they are all registering two to three stops under for just about any scene in good, constant light (i.e. no backlighting). I checked it against two known working cameras (one film, one digital) and a Sekonic light meter. All three of those agree within 1/3 stop. I installed fresh batteries and checked all the settings (ISO, EC, metering, etc.). I can't understand how three different camera bodies could all have the same problem.

Unfortunately I only have the one SA-mount lens that I mentioned -- a Sigma 28-80 AF lens, and I tested across the entire aperture range. Could the lens be the culprit here? And if so, is there a way to test the cameras' meters without the lens? I don't have another SA-mount lens, but I do have some Pentax and Olympus lenses.

Thank you.

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    \$\begingroup\$ How are you setting sensitivity with the Sigma cameras? Are you loading DX encoded film, setting it manually, or just assuming it is at a given setting? Have you confirmed that the exposure compensation is centered at zero? \$\endgroup\$
    – Michael C
    Commented Jun 12, 2017 at 6:04
  • \$\begingroup\$ If you haven't actually taken photos, how do you know the cameras' internal metering isn't accurate? \$\endgroup\$
    – Carl Witthoft
    Commented Jun 12, 2017 at 11:16
  • \$\begingroup\$ @MichaelClark - As mentioned, I confirmed ISO (you can change it from the DX preset; I did not) and that exposure compensation is set to zero. Thanks. \$\endgroup\$
    – bvy
    Commented Jun 12, 2017 at 12:34
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    \$\begingroup\$ @CarlWitthoft - The camera gives you the aperture/shutter combination when you half press the release button. What clued me in was the flash indicator blinking in a daylit scene. \$\endgroup\$
    – bvy
    Commented Jun 12, 2017 at 12:34

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Since the lens is an important part of the metering process, no, you can't really test it without a lens mounted.

If I understand your question correctly, you have three bodies but one lens; if all three bodies show the same incorrect meter value, then the lens is most likely your culprit.

In your situation, I would do some testing, with a controlled scene and bracketed exposures, to confirm the incorrect readings; from this, you might be able to derive an offset to use.

Beyond that, you're going to have to acquire an additional lens or three to see if anything is different.

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  • \$\begingroup\$ Thanks. I plan to pick up a second lens. I should add that these cameras suffer from a manufacturing defect whereby the mirror becomes discolored as the camera ages (had to do with the glue used). Each body has a slightly discolored (magenta) mirror, and I wonder if and how this could affect meter readings. \$\endgroup\$
    – bvy
    Commented Jul 10, 2017 at 12:35

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