Why 2/3" and not S16 sized sensor?

[Jeff Kilgroe]

But how do you use 2/3rd's lenses on an S16 camera w/o having to window the sensor? And that, I imagine, would casue a host of resizing issues since S16 is not a multiple of 2/3rd's.

Oddly enough, there is an enlargement effect to the image circle or lens coverage due to the optical correction needed. B4 lenses on the RED One cover a bit beyond the 2K ~S16 area just fine.

 

[Justin Anderson]

I think 2/3" was picked because it is a widely accepted standard video format and supports a much broader range of available optics.
There are current gen 2/3" HD cameras out there with a native 1600 ISO rating, so I don't think there will be huge differences in noise,sensitivity and DR compared to S35.

This makes the most sense to me, and it's similar to other responses.

This answers my original question:
:closed2ur0:

 

[Gavin Stokes]

I was wondering why people were griping about Super-16 being bigger than 2/3", and found DPReview's succinct explanation of this outdated "measurement":

"Sensors are often referred to with a "type" designation using imperial fractions such as 1/1.8" or 2/3" which are larger than the actual sensor diameters. The type designation harks back to a set of standard sizes given to TV camera tubes in the 50's [sic]. These sizes were typically 1/2", 2/3" etc. The size designation does not define the diagonal of the sensor area but rather the outer diameter of the long glass envelope of the tube. Engineers soon discovered that for various reasons the usable area of this imaging plane was approximately two thirds of the designated size. This designation has clearly stuck (although it should have been thrown out long ago). There appears to be no specific mathematical relationship between the diameter of the imaging circle and the sensor size, although it is always roughly two thirds."

 

[David Rasberry]

It really makes more sense to me to think of 2/3" format Scarlet as digital 16mm as they share the same optical image circle spec of 11mm. The original 4:3 2/3" format almost exactly matches the size of the 16mm TV projection aperture.