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Is the GH2 display always representative for spotting light/beamer interference?
  • Hi,

    I'm an audiovisual performance artist, working a lot with projections and other artificial light sources. I got me a GH2 to document my work and I was wondering if the GH2's display is always accurate for spotting interference of shutter speed, frame rate and electric light sources resulting in flickering and pulsing in the recording. The display has a refresh rate itself so I could imagine it adds an inaccuracy factor. Anyone's got advice on this?

    Thanks, Dieter

  • 5 Replies sorted by
  • Not really, it might be a hint, but you should do some tests at home first. If you work with 60hz refresh on the projector I would use 24p with 80% speed, resulting in 30FPS. LCD projectors cause much less problems than DLP.

  • I did some extensive testing this afternoon. I have Cake2.1 loaded.

    I tested both PAL and NTSC in HBR, 24P and 720P modes. In each test I set the beamers (BenQ MS612ST, DLP...) to 60, 75 and 85hz consecutively. First full white projection to check banding and flicker, then animated graphics to check motion.

    In all modes only shutter speeds 40 and 20 have no or very little flicker and banding. Other shutter speeds have very bad RGB stripes scrolling up (nice psychedelic effect though ;).

    720p60 at ss40 and beamers set at 60hz came out as overall best. 720p50 and other beamer rates have slightly worse flicker and motion, but only when looking very closely. SS40 is bad for fast motion but the RGB stripes of faster shutter speeds are worse so I'll go with that...

    Oh and actually the GH2's display is actually ok for spotting interference with my beamers. I already had found SS40 as potential best before turning to the computer.

  • it's easy to see what works for one light source. And getting close for a beamer should be no problem. However, when there are multiple sources that might interfer - the display is not sufficient to work out how interference affects the image.

    I would advice to check closely in both well lit and dark regions (any thinkable scenario, really) if you are doing an important project.

  • i see!

    my project only has light from 3 synced beamers so i should be fine.

  • @dtr sounds good! I was just inclined to comment since there have been some surprises with multiple light sources involved. I've noticed that a well exposed shot might look OK but when shooting a darker spot with the same settings / same lights, interference started to show (in the files; not necessarily in the camera).