Here’s what he had to say:
Freya: So the camera is now even better in low light levels than before?
ISO range is now bumped up, it used to be (and will remain so in current models) ISO640 to ISO20,000, with the update it becomes ISO2,000 to ISO64,000. From what I could tell noise levels are in line with that, i.e. ISO2000 looks like ISO640 on the old model and this carries on up the scale which is pretty spectacular. That could do with more testing by someone, I couldn't quite believe it when I saw it, ISO20,000 is definitely usable now when it definitely wasn't before.
Freya: So am I understanding what you are saying is that the lowest ISO is now 2000! Does this mean that ND filters become a lot more important?
Yes and yes! Can't go below ISO2000, basically no noise at ISO2000, crazy stuff.
Freya: Does the upgrade help with shooting high speed footage at all?
In fact the upgrade helps high speed a lot. High speed requires high shutter speed, which means less light. If there's not much light then you're going to struggle to get the high shutter speed without bumping up the ISO and the high speed mode runs even more noisy than normal as the sensor is hotter. The firmware update upgrades the base ISO to ISO2000 which is incredible, it makes the camera around 1.5 stops better in low light than it was before. ISO2000 looks like ISO640 and the noise grain appears better, perhaps finer, I'm not really sure why but it's like having a new camera.
Freya: Is the HDMI out still only 8bit?
Many of us were hoping the upgrade would make it real 10 bit out but Convergent Design are pretty sure it's still only 8 bit so it seems a safe bet it's not. It's a real shame as log isn't really suited to 8 bit as it requires grading, it's better than not being there but I'd be wary of using it for skin tones, need to test that.
Freya: How was the S-Log2 when recording to the internal H.264?
I did all my recording to the internal H264 and in short SLOG2 grades well, at least better than I thought! I expected cramming so much (perhaps 13-13.5 stops) dynamic range into an 8 bit image seems counter intuitive, log is usually recorded to 10 bit and higher but I believe even with an external recorder you are only getting 8 bit 422 even after the update. Having said this I've just graded lots of very low DR footage from the beach, all shot in 8 bit SLOG2 and I didn't have any serious colour depth problems and could get the kind of look I was aiming for (I grade in Premiere, usually using just colour correction and curves, old school!). That look however may be more tricky if you're for instance filming people's faces, skin tones in 8 bit don't grade very well so if you're filming say a close up of an actor SLOG2 probably isn't the right profile to use, something more contrasty that requires less grading will probably give you better skin tones. So in short, if you're shooting in controlled lighting situations SLOG2 might not be the way to go, for many other situations I think it's very useful and I'll personally be using it a lot. Having more DR gives you a more filmic look.
Update: Toby wrote to tell me that since his testing with the new camera firmware, he has further discovered that the minimum ISO value varies depending on which gamma curve you are using. It works out that Cine2 uses ISO 320, Cine4 ISO 640 and the new S-Log2 uses ISO 2000 as the base value.
To be honest this actually sounds a lot better to me as you can pick the right gamma curve that matches the ISO range you need, rather than having to pile on the ND filters. This should give more choices to the cinematographer, making the camera more versatile and making it easier to get the right look whatever the situation with light levels. S-Log-2 for low light and Cine2 on a very bright sunny day perhaps.
So even more good news it would seem. You aren't limited to ISO 2000 as a minimum after all.