Canon 350D Sync performance

The following is a test of how well my Canon 350D synchronizes with itself. What I mean by that is the difference between the delays of several shots. This way it is possible to predict the sync of a stereo rig if I had a second camera identical to this one.

An oscilloscope is used to measure the delay between the Remote Shutter and the Hot Shoe flash trigger of the camera, which can be taken as a proxy for the actual photo shot. The first photo shows the oscilloscope setup, the other ones show the screen traces. Each screen shows the traces of several shots superimposed on each other, so the randomness of the delays is clearly shown. Note that if there were no delay dispersion, the stereo sync respect an identical camera would be perfect.

The tests show the photo is taken ~100ms after the trigger switch. The 5th screen is for shots with the mirror locked, in which case the delay shortens to ~40ms. What matters however is not the absolute delay, but its degree of randomness, which leads to stereo mis-synch respect another camera, even if it were identical. Regardless on whether the mirror is locked or not, the dispersion shows about the same: ~1ms. This is the maximum difference between the earliest trigger and the latest, except for some rare outlier shots shown in figs 3 and 4. Something like one shot every twenty was an outlier, though with the mirror locked I didn't notice any.

Canon 350D can also do three bracketing shots at different light settings, which is interesting for HDR. I measured the sync of the third shot, and I was surprised to find it is almost as good as the one of the single shots. Outliers seem more frequent though. The last two screens show the results.

On conclusion if I had another camera like this, then the worst mis-synch difference would be 1ms, but on average most stereo shots should be significantly better (except for those outlier shots).

Antonio Fernández Galaz



The Photo Viewers are from:

  - 3D: HTML5 Viewer. Credits to several people I am not sure which

  - 2D: Lightbox2 photo viewer by Lokesh Dhakar