A7S left/right sensor split

I'm noticing a curious feature in an astrophotography master flat frame.  I've taken 16 flat frames at ISO 100 and summed them.  Stretching the result I see a vertical (left/right) discontinuity precisely at the centre line of the sensor:

If I completely saturate the colour I see wide horizontal banding effect on the left hand side whilst the right hand side looks completely normal:

These effects appear to happen at all ISOs and on both telescopes and lenses.

I wonder what might be causing it?

Mark

sharkmelley wrote:

I'm noticing a curious feature in an astrophotography master flat frame. I've taken 16 flat frames at ISO 100 and summed them. Stretching the result I see a vertical (left/right) discontinuity precisely at the centre line of the sensor:

If I completely saturate the colour I see wide horizontal banding effect on the left hand side whilst the right hand side looks completely normal:

These effects appear to happen at all ISOs and on both telescopes and lenses.

I wonder what might be causing it?

Mark

big sensors are manufactured from more than one exposure in lithography process

for example = http://blog.teledynedalsa.com/2012/02/the-art-of-making-large-image-sensors-or-quilting-with-silicon/

http://www.rawdigger.com/howtouse/rawdigger-histograms-overexposure-shapes = fig. 30

exdeejjjaaaa wrote:

big sensors are manufactured from more than one exposure in lithography process

for example = http://blog.teledynedalsa.com/2012/02/the-art-of-making-large-image-sensors-or-quilting-with-silicon/

http://www.rawdigger.com/howtouse/rawdigger-histograms-overexposure-shapes = fig. 30

Thanks for that very helpful reply.

Mark