[Bulb Timer] Exposure value isn't exactly what was set

Issue #2070 resolved
lloyd created an issue

Using the Bulb Timer, I noticed the exposure value in the image that was taken isn't exactly what was set. For example, I set the Bulb Timer to 10s, after the image was taken and reviewing the image the exposure value at the upper left of the image shows 10"6 (same for exposure more than 30 sec). I went ahead to M mode (turned off Bulb Timer at this point) and set exposure to 10 seconds to do another test. Reviewing the image shows exactly 10". Thoughts?

The said behavior is somewhat similar to what most external remote/intervalometer gives wherein the exposure value isn't exactly set for taking the image.

magiclantern-Nightly.2014Jul18.6D113

Comments (3)

  1. lloyd reporter

    Hi A1ex, saw your commit with a comment in the code [not tested] so I went ahead and tested it. I tried a 10s exposure again and instead of 10"6 it is now 10"1 although for longer exposures, say, 1m, it displays 60"3. I guess what the const does is to make it as close as possible but not make it exact, correct?

  2. Alex

    For the exact value, we should compare it with a regular shot, and tweak it until we get the same exposure. You can try that with a static scene, and the Post Deflicker tool.

    Problem: regular exposures don't match the displayed times either. I know 15s is actually 16s, 30s is actually 32s, but I'm not very sure about the others (you could check by recording the shutter sound). And 16 seconds is a bit too much for getting an accurate exposure difference.

  3. Log in to comment