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focus braceting and vibration
Posted: Thu Dec 24, 2020 6:26 pm
by Wildflower-nut
We all know about mirror slap causing vibration that the camera sees at certain shutter speeds.
Shutter curtain slap causes much less vibration but has been demonstrated to exist. Hence electronic first curtain.
In focus bracketing on Canon R5, the electronic shutter is used. The various exposures go rather quickly one after another. Between each exposure, the camera is using the autofocus to change the focus distance. Things are moving. Has anyone seen a discussion of having vibration induced by this motion that is recorded by the camera (motion blur)?
Posted: Fri Dec 25, 2020 6:34 am
by E.J. Peiker
I have not used Canon's focus bracketing but most camera systems allow the option to induce a delay between each shot. That said, even doing it in rapid succession, I have not found focus travel induced vibration to be an issue on other cameras.
Re:
Posted: Fri Dec 25, 2020 2:19 pm
by Wildflower-nut
E.J. Peiker wrote:I have not used Canon's focus bracketing but most camera systems allow the option to induce a delay between each shot. That said, even doing it in rapid succession, I have not found focus travel induced vibration to be an issue on other cameras.
I'm looking at doing macro flower photography in the field. I've steered away from stack focus in this situation because of the need for absolute stillness and the length of time it takes to make focus adjustment between exposures. Therefore I've limited its application to studio or landscape. The canon focus bracketing goes fast enough that having the subject still that long is possible. To get DOF the traditional way, I'm ending up many times with exposures between 1/15 and 1/2 second. With mirror lockup and electronic first curtain that is not an issue. With the wider aperture that focus bracketing allows and the kind of ISO's available (say 400 not 26,000), each individual exposure may have a shutter speed that will freeze any auto-focus induced motion. We used to say that shutter speeds of 1/30 and above would freeze mirror slap or at least reducing its influence to acceptable levels. Even if focus vibrations do occur, there should be a shutter speed, either faster or slower, where their influence is minimal. I need to do some experimenting.