LV5 won't trigger my EOS7D

Well, that's not strictly true...

To test, I set up a dart on a thread, falling through the laser beam.

If I lower the dart through the beam the trigger operates, and a wireless V5 on the camera triggers the shutter. So far so good...

If I DROP the dart (from any height, t doesn't mater) I can see the sensor LED flash to red and back to green, but the camera shutter doesn't fire.

I tried increasing freeze - right up to 90ms - and at 90ms it seems to fire.

Is this behaviour expected (due to shutter delay)? I have read in detailed reviews that the shutter lag on the 7D is classed as fast so it seems odd that I have to go so far on the freeze in order to get the shutter to fire, but I can see the V5 receiver is being triggered by the sensor at all freeze values (including NIL) as the V5 LED flashes every time.

It does mean that for high-speed shots one needs to trigger well in advance and know where the object is going, which could make it useless as a setup for wildlife (insects etc)?

Thanks for any pointers.



  • edited March 2015 PM
    There are two issues here:

    Your camera needs a minimum length for a shutter release signal. If a recognised event is shorter than this minimum length, your camera won't fire (but a V5 will recognise the event nevertheless).

    You can address this by either increasing the freeze value, as you did, because that increases the shutter release signal length.

    Or, you may want to try "multi-shot" mode which should generate a longer shutter release signal, unless there are many rapid events following each other.

    The second issue, is that of shutter lag, i.e., the potential problem that if the camera fires, the object has moved on already.

    There is no way around that other than using a good camera placement, or -- for certain high-speed applications -- keeping the shutter open in a dark environment and trigger a flash with the LV5, instead of the camera.
  • Thanks for the pointers.

    I shall maybe try the multi-shot mode and see if that is a better workaround.

    Shutter lag on the 7D is, according to the detailed technical reviews I read that actually include such data, considered fast, but even then the figures in reviews/specs seem to match the delay I am seeing.

    I'm not sure whether there are cameras with lower lag - if this is fast in general terms, it must be even harder for those with slower cameras!

    A dark environment using "bulb" mode would certainly answer for some types of shot but for wildlife it clearly isn't an option...

    Thanks again.

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