This is a demo of the zoom range and clarity at a full 600mm (as well as the OIS at that focal length):

Sony RX10M3 zoom test on Vimeo

So is this camera parfocal over the entire range then?
What f-stop was this shot at?

I believe it was f4.

The camera is not advertised as 'parfocal', but for the most part it behaves that way.

It looks like the stabilization also has been improved, there are 2 things that annoy me about my mark 1 and that's the jitter I get when zoomed in and the super slow zoom. My rx10 has become my favorite camera to use at weddings during the first part of the day just because it's so easy to use, only the slow zoom made me miss some important moments because it takes about 13 seconds from tele to wide which is ridiculous.

Yeah, I still use my RX10 mark -1 and love this however I wish it had the same focus settings like the A7s. I have a button setup on the back of the A7s for quick focusing where as the RX10 I find weird you can't set this up.

I wonder if the latest versions have the ability to use a back focus button?

I can toggle between autofocus and manual focus with the button on the back of the camera, is that not what you are referring to?

No, It doesn't function the same as the A7s mate.
A7s functions in video mode like a still camera although when in record mode it's slow to focus however this works really well, bit like pulling focus.

I think he means Back Button Focus
You can assign this to a button on the back of some cams rather than using the half press on the Shutter button to acquire focus, you press the back button once to lock the focus. Then, take the photo in the usual way using the shutter button but without needing to keep finding focus.

Or then you dont mean the above!

Yes, back focus button, I can't use this on the RX10 in video mode.

I know t works a bit in a different way compared to a dslr but is the result not pretty much the same? I can have the focus in manual on the rx10, press the backbutton and let it refocus and switch back to manual using the same button, when it refocuses it's also gradual and it's not snapping into focus like you often have with dslr's.

Nope , not on mine. When I first purchased mine I had issues and then sent this back for review. They found no issues with the camera and I have been stuck with this problem. It's cool... I still use the thing all time although trying to focus is an issue at times. What I have to do is use auto focus then lock this into manual focus, unbelievable.

There seem to be a lot of little "issues" with the mark 1, I have had my share, that's for sure but I still like using it because it's so easy to shoot with.

Yes, I had been following you and your problems. I really like the RX 10 and the fixed lens, perfect just to pull out of your bag and start shooting both for stills and video. If Sony made the a6000 series with a fixed lens, this would be a winner.

Here's a quick 4K video I shot with the new RX10III. Many of these shots were at or near the full 600mm limit of the lens. So this was a great test of the clarity of the lens, the effectiveness of the OIS at these high magnifications (no tripod used), color quality and how efficient the AF is:

Select '4K' if you're streaming or download the original 4K video from the download section:

Sony RX10III 4K-Grist Mill Lake on Vimeo