5K iMac Motion Issues with Films

Discussion in 'iMac' started by Marko5000, Aug 22, 2015.

  1. Marko5000 macrumors newbie

    Aug 22, 2015
    My first post here. Looking for advise/reassurance from current owners.

    I'm currently considering a 5K iMac but have one small concern. Although the iMac will be used mainly for photo/video work it will also become my only device for watching movies. Currently using a MacBook Pro w/retina and use iTunes/Netflix and am incredibly happy with the quality (if not the size).

    Whilst using the iMac in store I watched the two samples of HD movies in iTunes (Hobbit and Lego Movie) and was concerned to see some motion issues with objects moving across the screen (edges of buildings, Gandalf's hat etc.). Not quite a stuttering but a very obvious effect I never notice on either MacBook or my TV.

    Not sure if this is due to screen size, viewing distance in the store or my own sensitivity (I like a perfect picture).

    Does anyone use an iMac 5K for watching movies and if so do you ever spot this.

    Edit to say: I've seen other threads about rendering GUI and stuttering but a. I don't think this is what I am seeing and b. I'd probably be holding of for the next update anyway
  2. Mr Dobey macrumors 6502

    Aug 8, 2008
    If you are watching a film shot in 24fps there will be a slight Judder (stuttering) since 24 is not an even multiple of the iMac's native 60Hz refresh rate. This effect is much more noticeable on a larger higher resolution screen explaining why you have not noticed it with your laptop. If you have a newer TV that supports a native refresh rate of 120Hz this effect will not occur since 120 is a multiple of 24.
  3. Marko5000 thread starter macrumors newbie

    Aug 22, 2015
    TV is also 60Hz but obviously watched at a much greater relative viewing distance (42inch at ~ 12 feet).

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