Marie Davignon Posted June 17, 2011 Share Posted June 17, 2011 I have an important question : Do I need to use flicker free HMI ballasts when shooting with the Alexa at 24 fps? 23,97? Does it work like the RED, with a rolling shutter that can make some lines moving through the frame? Thanks! Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted June 17, 2011 Premium Member Share Posted June 17, 2011 I haven't had problems with older HMI's on either the Red or Alexa. Yes, the Alexa has CMOS sensor with a rolling shutter. At 23.98 fps, you are on the edge of flicker but usually it's not noticeable unless you look at a waveform monitor. Link to comment Share on other sites More sharing options...
Marie Davignon Posted June 19, 2011 Author Share Posted June 19, 2011 Thanks! Link to comment Share on other sites More sharing options...
Premium Member Phil Rhodes Posted June 19, 2011 Premium Member Share Posted June 19, 2011 I have seen a 60Hz HMI flicker on a 7D at 1/60 shutter. There appear to be no rules. P Link to comment Share on other sites More sharing options...
Gregory Middleton Posted June 28, 2011 Share Posted June 28, 2011 Its always safer to shoot flicker free. You should be able to see any issues on the waveform however. Sometimes it will only show up from 1 light or at a particular angle depending on conditions as a very slow pulsing density shift. Flicker free will make sure however of no issues at 23.98 Beware fluorescents in locations with magnetic ballasts however. I have an important question : Do I need to use flicker free HMI ballasts when shooting with the Alexa at 24 fps? 23,97? Does it work like the RED, with a rolling shutter that can make some lines moving through the frame? Thanks! Link to comment Share on other sites More sharing options...
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