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GX7's video is too dark in low light VS EM5's video

Discussion in 'Panasonic Cameras' started by Halaking, Jan 19, 2015.

  1. Halaking

    Halaking Mu-43 Top Veteran

    667
    Dec 17, 2012
    Los Angeles
    Morris
    I just got the GX7 few weeks ago, when I test GX7's video, I clearly say using the kit lens 14-42mm 3.5-5.6 and the videos took in low light are too dark. I'm using auto mode auto ISO and the highest limit for video is 3200,. First, I thoguht used large number apertures lens and the ISO 3200 is not enough, but after I compared with EM5 &12-50mm 3.5-6.3 also have on auto mode and auto ISO 3200, I feel that all the GX7's videos in low light are about -1~1.50 EV, any idea? thanks!
     
  2. wjiang

    wjiang Mu-43 Hall of Famer

    Maybe just different auto profiles? What do still shots in auto look like on each camera?

    I use custom picture profiles that reduce contrast, saturation and sharpening for easier post processing, and the resulting video from the GM1 is a a bit nicer than that from the E-M5. I usually use shutter priority for video, with auto ISO and aperture.
     
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  3. Halaking

    Halaking Mu-43 Top Veteran

    667
    Dec 17, 2012
    Los Angeles
    Morris
    I also try the natural color profiles, basically it use less contrast and sharpness than standard color profiles, but same darker video, under the same lighting, EM5' with 12-50 3.5-6.3 output much brighter video.

    For images, I think Olympus is little brighter than Panasonic, it's about 1/6-1/3 EV, seems Panasonic usually little yellowish and darker under incandescent lighting, Panasonic older generation's sensors are worse, even RAW looks yellowish, but GX7's RAW is much better!

    I guess you right, maybe just different color profiles and output.
     
  4. John M Flores

    John M Flores Mu-43 All-Pro

    Jan 7, 2011
    Somerville, NJ
    Two lenses with the same aperture may be transmitting different light levels to the sensor due to number of elements in the lens, coatings, lens design, etc... Look up T-stop, which is a measure of light transmission vs. F-stop, which is a ratio of focal length to aperture opening IIRC.
     
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  5. Halaking

    Halaking Mu-43 Top Veteran

    667
    Dec 17, 2012
    Los Angeles
    Morris
    Great explanation!!

    I also found out I forgot that I set my EM5 +1/6 EV in EV adjustment, that makes some difference.

    Thanks for replies.
     
  6. monorail

    monorail New to Mu-43

    3
    Jan 20, 2015
    This might have to do with the fact that the HD frame rate for the EM-5 is 60fps interlaced, whereas for the GX7 it is 60fps progressive. With interlaced, the camera is essentially capturing 30fps, allowing a slower shutter speed. So, if both cameras are in auto mode at the same maximum ISO and the same aperture, the EM-5 (at 30fps/60i) could record at 1/2 the shutter speed of the GX7 (at 60fps progressive. Of course, you could adjust the GX7 frame rate to 30 or 24fps).

    At least, I think that's correct. I have a GX7, but unfortunately when you shoot video in auto mode it won't tell you what shutter speed it's using. So, who knows what's really going on. I always, always use manual video mode.

    The GX7 has a hidden feature you might find useful for low-light video: in manual video mode, with the camera set to manual focus, you can use shutter speeds as slow as 1/2 second, even with a frame rate of 60fps. This seems like it should not be possible... and it's not, really. But what happens is the exposure gets applied to multiple frames, giving you a slower effective frame rate. Obviously this introduces motion blur--- a little blur at 1/15s, a whole lot at 1/2s. But it does enable much lower-light shooting, and the blur can be a useful effect even in normal light (for instance, video of moving water such as a waterfall can benefit from a little blur. And blurred passing trains can be pretty cool). For some reason, this feature only works with manual focus-- if it's set to auto-focus, you can only go down to 1/30s shutter speed. But manual focus is better anyway.
     
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  7. Halaking

    Halaking Mu-43 Top Veteran

    667
    Dec 17, 2012
    Los Angeles
    Morris
    It might be the interlaced VS progressive, I'll try it in manual when I get the chance.

    Thanks for the useful tip, slow motion blur effect surely works on many situation, great feature!!
     
  8. Bif

    Bif Mu-43 Veteran

    380
    May 28, 2012
    San Angelo TX
    Bruce Foreman
    • Like Like x 1
  9. Halaking

    Halaking Mu-43 Top Veteran

    667
    Dec 17, 2012
    Los Angeles
    Morris
    Thanks for tip and very informative posts.