Projection flickering problem

  • hello everybody
    there is something that's baffling me and for which some help would be highly appreciated...
    not strictly to do with Isadora but I need some help.
    I thing maybe related to Mountain Lion, or maybe not...
    I'm in rehearsing stage with Isadora 2 and 4 projectors for a video clip
    Independently from what is going to Isadora, I use an analogue Matrox DH .
    2 of the projectors are receiving video from DVD players and these are fine.
    The 2 projectors fed by my MacBP 17" 2009, with Mountain Lion OS are FLICKERING, I tried every possibility, changing cables, direct projection without the Matrox, nothing, still flickering,
    Tried to connect the Projectors to an UPS to stabilize electricity (working in a village in south Portugal), nothing.
    It never happened to me before.
    It cannot be seen by the naked eye, only trough the lens of a Canon DSLR camera that I need to use to film the subject with the projection backgrounds. Of course I tried to change shutter speed (I'm using Magic Lantern with 180º).
    Tried to change the frequency on the projectors and on the Mac  without improvement.
    I could not find the way to change the Hz rate on the MBP any more, I do recall that it was possible to change it on previous OS.
    Is possible to change the frequency rate on the Matrox control panel but there is not 50 Hz.
    If there is someone there that had to go trough something similar, please share your outcomes.

  • Tech Staff

    Are you using the Movie Player Direct?

  • I'm confused but is nothing to do with Isadora, Using my Sony EX3 camera I fund out that with the shutter set to 60 or multiples it does not show any flickering. it has to do with the fact that I can't change the mac from 50 to 60 Hz, although both projectors and mac are using the same electricity supply (of course at 50Hz)... The Canon with Magic Lantern does not have the possibility to set to exact 60, only 64 and does not have 30.... sigh

  • using NTSC on the 60D it does not show the flickering... what's wrong?

  • Tech Staff


    If you can't set the mac to 50hz try switchResX, there you can set additional settings. SwitchResX is a bit complicated in beginning but does the job.


  • it is a system "bug" you can't mix both worlds without conflicts or expensive framerate converters

    ideally you would try to match your footages framerate with the projector, if you are living in europe and pal is the choice
    an edid emulator could help, as most display devices having a burnt edid with a default resolution of 60hz
    and osx is quite stubborn with other frame rates resolutions
    the other fact is that the old dual heads don't support 50hz
    as they are made and marketed for this default displays
    the new one shall be capable but only with tv resolutions 720p50 etc. 
    you could try [switchresx](

  • thanks all, investigation in progress
    I installed the switchresx
    one question, could this adversely affect the old dual heads operation?

  • Tech Staff

    I have no idea.