Here’s a test which shows what I feared and what very few seemingly dared ask Sony in interviews at NAB. The A7S looks to have similarly extreme rolling shutter to the AX100, at least in the early pre-production firmware stages.
Let’s hope Sony can reduce this as much as possible in the final camera.
With a sensor which outputs every pixel – and so many of them at 4K – the chances of heavy rolling shutter are increased, unless the readout speed of the sensor is also increased (which is the case with the GH4, by a factor of 50% over the GH3).
Even in 1080p XAVC-S mode on the A7S the sensor is still scanning every line and every pixel so the rolling shutter is likely to be the same in that mode. It will be interesting to see if it improves between 24p and 60p modes though, but I was hoping that 4K 24p would not suffer from quite some much wobble.
Rolling shutter can be corrected to a degree in post though and the extra resolution 4K provides helps soften the blow of the necessary crop when doing this, but then that impacts on the full frame rendering of your lenses, which is the main selling point of the A7S along with its low light performance.
For locked down shots with slow movement or steady handheld work usually you can get away with some heavy rolling shutter. The BMCC 2.5K camera had quite a bit of it. For action or more violent camera work though it really is a deal breaker.
It’s worth mentioning that Kinefinity have a solution to reduce rolling shutter in their cameras called Sports Mode. Maybe Sony can implement something similar?
With a fast sensor in a very small body even at just 12MP heat is always going to be an issue especially with a large chip, so I can see why Sony might be limited by the hardware when it comes to rolling shutter.
Given the low price of these cameras it seems reasonable to consider using both the GH4 and the A7S, applying each camera when a scene might play to their individual strengths.
However Sony recently tested the water on a higher price point via UK retailers in the region of $4k to gauge customer feedback.
I really don’t think the A7S is worthy of that price as it would end up close to $6k or $7k when paired with the necessary recorder to use 4K over HDMI.
Let’s keep the price at A7 levels Sony!