GH2 Does ETC Mode Affect Rolling Shutter Jello?

M

mpgxsvcd

Veteran
This video shows the Jello Effect when ETC mode is used. I used the 14-140mm @ 35mm plus the 3.9x 720p ETC and the 14-140mm @ 140mm to give the same equivalent field of view. There is a theory that using a smaller portion of the sensor should enable the camera to readout the entire sensor faster and thereby reduce the rolling shutter effect.

I filmed passing trucks at the same speed with 1/250th shutter speed. I could not tell any difference in the angle of distortion between the two clips. A lot of people think that rolling shutters only affect the video if the camera is moving. It will actually slant vertical lines if the subject is moving fast enough horizontally even if the camera is still.

I do not believe that using ETC mode over just the lens has any affect on the rolling shutter jello effect. Theoretically sensor readout speed is the only thing that could affect it. Using ETC mode should reduce the number of pixels that the camera reads. However, that does not appear to help at all. Instead it appears to read the entire sensor in the same time that it takes to read it without using ETC. Maybe it is just throwing out the data that the ETC mode doesn't need?

http://www.youtube.com/watch?v=ayLECr2E2N0

 
Kholi said:
Did you actually try 1080 24 instead of 720?
Click to expand...

Yes I tried 24p. I tried it at 1/25th of second, 1/50th, 1/125th, and 1/250th. I tried the same for 1080p @ 30 FPS as well. Turning ETC mode on does not improve rolling shutter for the GH2 period. The reason why the video was shot with 720p @ 60 FPS and 1/250th shutter speed for the main clips was because those are the settings where the ETC mode should offer the most improvement if it actually offered an improvement.

Sensor readout speed affects rolling shutter more than anything else. With 720p @ 60 FPS and 1/250th of a second shutter speed you maximize the sensor readout speed. This eliminates the sensor read speed as a factor in the test and isolates the ETC mode as the only variable.

If you want to minimize rolling shutter then shoot with 720p @ 60 FPS and a 1/125th of a second shutter speed. Using ETC or not using it is irrelevant for rolling shutter with the GH2.
 
I meant did you try 1080/24 ETC instead of 720/60 ETC. Just from personal experience, always using ETC mode, I noticed a major difference because I'm always handheld I have very shakey hands.
 
Okay the video finally loaded, had some trouble getting it to play here at the office (as usual).

Did you do a freeze frame of the 1080 ETC and Non ETC? I noticed a freeze frame of the 720, but not the 1080. At first glance the ETC 1080 does look better to my eyes but a freeze frame (like you did with the 720) may illustrate something different. I've never tested it, I just know that my hands shake like crazy and it seemed reduced drastically in ETC (the sway and bend aka Jello not my hands shaking) but I've never come to a conclusion either way.
 
ETC mode seems far less jello-y to me as well which is weird given that these tests so far haven't really borne that out. I don't think I'm imagining things, though. Shaky footage on ETC feels a lot more solid to me like my old DVX footage, the image has an integrity to it that the full sensor sometimes doesn't.
 
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