A7s Sensor Size?

[Brian Caldwell]

Thanks in advance if anybody can help me track down the following information.  I need to know the exact dimensions of the 16x9 video frame used by the Sony A7s-II in both 4k and 2k video modes.  All that I'm confident about are the following:

1) full still sensor size measures 35.8mm x 23.9mm

2) full sensor resolution in still mode is 4240 x 2832.

3) 1 and 2 together imply a pixel dimension of approximately 8.44 microns square

4) 4k video resolution is 3840 x 2160.

SO:  does this mean that the rectangle of sensor area used during 4k recording is 32.41mm x 18.23mm? 

Similarly, what would be the as-used sensor dimension when shooting 4k in "full-frame" mode?

 

[IronFilm]

Is a medium format focal  reducer coming? :-D

[Brian Caldwell]

4 hours ago, Ebrahim Saadawi said:

People: please answer this question for @Brian Caldwell it's very likely a research into a very exciting item we all wish to exist!

Brian: if it's any help. The A7s, in my experience, when used in 1080p HD internal mode, uses the full width of the sensor so 4240 pixels and just crops the vertical dimension to 16:9 ratio. Can't personally calculate how many pixel vertically would be used. So it downscales 4240 to 1920 internally for HD. 

When used with an external recorder to record the 4K stream, I noticed a slight crop. Which certainly means the A7s, in 4K mode externally, uses a 1:1 pixel readout which is 3840 crop from 4240. That's about a 1.1-ish crop over the FF 36mm width.  

This is all in my experience with the A7s MARK ONE. NOT TWO. So it might have changed any anyway. 

Thanks Ebrahim.  As always, your contributions here are extremely helpful.  What you are reporting is what I suspected, but its really nice to get confirmation like this since I don't have the camera myself.

FWIW, I am doing research for a product, but its for a system of anamorphic lenses and not a fullframe Speed Booster, which may not be what you were hoping for but which I promise will be very cool.  

[IronFilm]

On 7/25/2016 at 7:18 AM, Brian Caldwell said:

Thanks Ebrahim.  As always, your contributions here are extremely helpful.  What you are reporting is what I suspected, but its really nice to get confirmation like this since I don't have the camera myself.

 

Brian, I recommend you take what he posts with a very very large grain of salt. (not saying what he said is true or false however)