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Jello-cam in "The Martian"


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#1 Keith Walters

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Posted 09 November 2015 - 05:46 PM

I was sort of under the impression that CMOS sensor image skew, (also known as "Jello-Cam" ) had been eliminated, at least in High End cameras.

 

But I noticed on "The Martian"  (mostly shot with Red cameras) some pretty severe skew artifacts on the set's LCD video screens when the spacecraft was getting trashed by the sandstorm.

 

Would you expect to see the same result with an Alexa or F65?

 

If nothing else, an LCD screen looks like a good test of skew performance, since it's nice and rectangular, and you know the aspect ratio.


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#2 Phil Rhodes

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Posted 09 November 2015 - 06:52 PM

Most Alexas are rolling-shutter cameras. F65 and the optical-viewfinder Alexa has, optionally, a mechanical shutter, so that the sensor is physically obscured from light during the readout, so they do not suffer rolling shutter artefacts, at least no more than 35mm film ever did.

 

The electronic shutter on a conventional Alexa is extremely fast, however, so it isn't generally objectionable. It can be revealed by things like xenon strobes, which ramp up and down in brightness extremely quickly, to the point where bullets can be frozen in flight by quite conventional photo flashguns. Alexa can and does show flash banding; look at the gunshots in the Terminator Genisys trailer.

 

I suspect that the images feeding the LCDs in The Martian did not arise from the production camera.

 

P


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#3 Keith Walters

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Posted 09 November 2015 - 07:02 PM


I suspect that the images feeding the LCDs in The Martian did not arise from the production camera.

 

P

No, you couldn't see anything on them; they just appeared as burned-out white rectangles. Well, trapeziums, (trapezia?) to be more precise :rolleyes: .


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#4 Phil Rhodes

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Posted 09 November 2015 - 07:11 PM

Oh, I see, you're talking about the images of the displays as shot by the production camera.

 

Well, yes, Red.

 

P


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#5 Keith Walters

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Posted 09 November 2015 - 07:42 PM

Oh, I see, you're talking about the images of the displays as shot by the production camera.

 

Well, yes, Red.

 

P

Biafratography roolz!


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