A shutter curtain moves but a lens opening is stationary right? Instead of remaining stationary each time a photo is taken the lens diaphragm opens fully before dialing down to the selected aperture just before the shutter fires.Įach time it moves from wide open to the desired f-stop small inconsistencies can occur and show up in our photos.
REMOVE FLUORESCENT LIGHT FLICKER PREMIERE MANUAL
Now normally when shooting in full manual mode you would think that the aperture setting or f-stop would remain perfectly constant between shots. The good news is that shutter flicker is usually much less pronounced and even easier to fully eliminate. Very small curtain timing inconsistencies from one frame to the next produce slightly brighter or slighter darker frames when we watch them together in quick succession. The faster the shutter speed the narrower the slit and the shorter the exposure. The result is a horizontal slit or gap that travels vertically across the image sensor. In order to get very quick exposures the second curtain is triggered before the first is fully opened. At faster shutter speeds both curtains need to be active at the same time.
The curtains then reset for the next shot and the process can be repeated. After the required exposure time the second curtain, which was in a folded state, is now released and expands to block the sensor. During slow shutter speeds the first curtain is released from an expanded position and folds downward revealing the image sensor. Think of two opaque curtains, somewhat accordion like, that can expand and collapse in front of the sensor. This quick chapter provides everything you need. If you like what you read, consider buying the full book. I asked Ryan if I could share the info with our readers and he gladly agreed. One of the chapters dealt with the issue of mechanical induced flicker which I thought was a great nugget for any one doing timelapses.
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