Some questions about various crop modes in camera

[freeman]

Hey everyone I have been thinking about this for a while and know there are a lot of great tech minded people on this forum so I want to ask some questions about in camera crop modes. 

 

My experience so far is with the GH2 and GH4. Both have an internal 2x tele-crop mode. From what I understand normally a larger amount of the sensor is read and then downscaled to output a final image. In the crop modes.. a smaller portion of the sensor is read at a higher resolution? (I know this is very basic but I am no electronics expert)

I also have a question for any Sony A7s owners out there about the Clear Image Zoom. I understand this to be a variable crop all the way up to 3x of the sensor. I am wondering about all of this because of my enthusiasm for using older 16mm glass which produce smaller image circles than modern 35mm lenses. I wonder if it's possible for most if not all mirrorless cameras to have various sensor crop modes to utilize different lens image circles. For example, the GH4 can shoot 4k in 16x9 as well as a 4:3 mode that is just bigger than a 16mm film frame. Is it reasonable to assume it's completely possible for a mode to be available to the GH4 to shoot a 16mm sized crop of it's sensor? 

 

If anyone has used the Sony clear image zoom at it's furthest crop mode (3x?) I have read it is about Super16 size. Anyone shot with super16 glass on a sony? My workarounds for using the GH4 for 16 and super16 lenses depend on it's 4k crop being 2.3x, but future GH models using smaller crops of the sensor for 4k would make those workarounds obsolete. I'm wondering if Sony is a better body to shoot with older glass. Anyone who has done experimenting I'd love to hear about what you have found. And if cameras can be hacked to output higher bitrates.. maybe they can be hacked to shoot in different aspect ratios. However that must be deep into the firmware. 

Thanks for reading.