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    #11
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    Assuming some vertical shake/bounce from running is being transmitted through the Ronin into the camera- which is possible as gimbals can only correct for vertical tilting, not vertical travel (aka booming or jibbing)- this is probably the result of the sensor bouncing a bit inside the camera (even with IBIS turned off)- something I was disappointed to discover does indeed happen with my G85 (and I would assume the GH5 would be the same).

    I was able to test this by using a fisheye with an undersized image circle (gives a semi-circular image) and shaking the camera fairly hard. The image did indeed bounce/shake at the end of my movements. It's not the lens moving on the camera, so the only explanation is that the sensor is moving. Apparently the magnetic IBIS system isn't able to completely "lock down" the sensor, as it obviously would be in a non-IBIS camera (i.e. your GH4).

    Now, this would be pretty much a non-issue on any non-fisheye (or possibly an extremely wide rectilinear lens), because the amount of shaking needed to move the sensor is way past the point where you can still get usable footage. So by the time the sensor shakes, your footage is well into earthquake-o-vision anyways, so who cares.

    But with a fisheye, the AOV is so incredibly wide that you can get away with shaking the camera a fair bit, and the image won't move enough in relation to the frame to be unusable. In fact it's usually still pretty damned usable. This is part of the reason why the action sports love fisheye lenses: they allow for simple one-handed camera operating, while skating/skiing/etc, with acceptably steady results, without much practice. With practice, way more than acceptable; even glidecam-like for a skilled filmer.

    The other reason we like fisheyes is why everyone else hates them: the distortion. It lets us exaggerate speed, size, impact, distance, etc. Very useful for making our sports look as impressive as possible. But in this case, the distortion is also probably revealing the movement of the sensor, as the image moves through it, which would be what gives the Bad-Warp-Stabilizer-type effect.


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    #12
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    Quote Originally Posted by aldolega View Post
    Assuming some vertical shake/bounce from running is being transmitted through the Ronin into the camera- which is possible as gimbals can only correct for vertical tilting, not vertical travel (aka booming or jibbing)- this is probably the result of the sensor bouncing a bit inside the camera (even with IBIS turned off)- something I was disappointed to discover does indeed happen with my G85 (and I would assume the GH5 would be the same).

    I was able to test this by using a fisheye with an undersized image circle (gives a semi-circular image) and shaking the camera fairly hard. The image did indeed bounce/shake at the end of my movements. It's not the lens moving on the camera, so the only explanation is that the sensor is moving. Apparently the magnetic IBIS system isn't able to completely "lock down" the sensor, as it obviously would be in a non-IBIS camera (i.e. your GH4).

    Now, this would be pretty much a non-issue on any non-fisheye (or possibly an extremely wide rectilinear lens), because the amount of shaking needed to move the sensor is way past the point where you can still get usable footage. So by the time the sensor shakes, your footage is well into earthquake-o-vision anyways, so who cares.

    But with a fisheye, the AOV is so incredibly wide that you can get away with shaking the camera a fair bit, and the image won't move enough in relation to the frame to be unusable. In fact it's usually still pretty damned usable. This is part of the reason why the action sports love fisheye lenses: they allow for simple one-handed camera operating, while skating/skiing/etc, with acceptably steady results, without much practice. With practice, way more than acceptable; even glidecam-like for a skilled filmer.

    The other reason we like fisheyes is why everyone else hates them: the distortion. It lets us exaggerate speed, size, impact, distance, etc. Very useful for making our sports look as impressive as possible. But in this case, the distortion is also probably revealing the movement of the sensor, as the image moves through it, which would be what gives the Bad-Warp-Stabilizer-type effect.
    This, more than anything I have been able to come up with, seems like a logical answer. And it is a very disappointing one. If anyone out there has any thoughts on what I can do to fix this issue, any info is appreciated.


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    #13
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    The only fix would be to switch to a camera with a fixed sensor (no IBIS), or to alter your gimbal technique or setup to keep the vertical shake from reaching the camera. Meaning:

    -run smoother

    -use skates/skateboard/Segway/skis/hoverboard, etc instead of running

    -mount the gimbal on a Steadicam vest/arm, which should isolate the camera from your vertical motion.


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    #14
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    Quote Originally Posted by aldolega View Post
    The only fix would be to switch to a camera with a fixed sensor (no IBIS), or to alter your gimbal technique or setup to keep the vertical shake from reaching the camera. Meaning:

    -run smoother

    -use skates/skateboard/Segway/skis/hoverboard, etc instead of running

    -mount the gimbal on a Steadicam vest/arm, which should isolate the camera from your vertical motion.
    Definitely aware of these things, but thank you for the response. It's really unfortunate to me that my brand new GH5 is underperforming my GH4 in these situations. If you need the stabilizer off, it should be off; that sensor should be locked in. I've been filming fisheye for 15 years, it's well known that when the lens is on you turn the stabilizer off. At this point I need a GH4 with 4k 60p. Very disappointed.


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    #15
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    Yea, it's a bit of a bummer for me too (only a bit as I don't have a GH5 yet, only the G85). I agree that the sensor should be totally locked down when off. To be fair to Panasonic though, this is a very rare/specific usage case. I'm disappointed but not surprised that they never caught this defect.

    For now I'm using the Samyang 7.5mm, which has plenty of room in its image circle for the sensor to move a bit without black corners creeping in. I haven't noticed any of the warping happening either, so it works for now- only problem being that it's not really wide/distorted enough for my tastes. At some point this summer I'm going to get one of the Meike 6.5mm f2 fisheyes off Amazon and use it for a couple days, to see if my typical usage causes the sensor to shake or not.


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