You'll remember that smartphones like the Lumia 930/1520 and of course the Lumia 950 and 950 XL all have OIS, i.e. their lenses are optically stabilised, meaning that small hand wobbles get compensated for and you can shoot more stable footage. And OIS generally works very well, though when you start factoring in significant movement it's clear that there are limits - physical limits because of the small size of the OIS mechanism.
Which is why Microsoft added 'Digital stabilisation' as an option (to 1080p footage and below), effectively using the processing power of the phone's GPU to analyse captured video frame by frame and 'lock on' to central subject detail, keeping it in the same position (within reason) by juggling the entire frame around it. Obviously if you pan the shot around then the software detects the trend early and adjusts its algorithms.
In practice, this works rather well. Some smartphone companies in the Android world have even gone down the route of only having digital stabilisation and foregoing OIS. My worry here for the Lumia 950 has always been that the OIS and digital stabilisation would 'fight' to some degree and the result would be a mess. Instead, the OIS tends to work on a different timescale and the two systems complement each other rather than conflict.
I did a short mention of all this and a test here, when Windows 10 Mobile hadn't yet been formally released, three years ago on the old Lumia 930, but I wanted to be a little more extreme here and also use the much newer and more capable Lumia 950 chipsets.
As usual for embedded video content, maximise the window and 'up' the quality, or click through to YouTube (click on the word itself) - depending on which device and browser you're using to view this page:
There's no commentary in the video, so here are a few notes:
- Digital stabilisation + OIS is almost always better - in the first (walking) test, you can see some processing artefacts in the frame, but the overall improvement in smoothness is worth it.
- OIS takes out the worst of hand wobble, but the result still looks phone-shot. While adding digital stabilisation as well takes the footage closer to being 'cinematic'. My test cases above were extreme, especially the driving video, bear in mind that real world video of places and people will be a lot smoother and more watchable.
- The driving video looks unwatchable in both cases, but look at the lorry in front of me - as central detail it's stable in the frame on the left and is wobbling like crazy with just OIS.
Bear in mind that the OIS used in the Lumia 950 range isn't bad - in fact, it's arguably as good as, or better than, anything else in the phone market, even today. But the duality of OIS plus digital stabilisation really is better and I'm struggling to think of any reason to turn it off.
Making it slightly puzzling why the default setting here is 'off'. At least on my Lumia 950 devices - maybe you know of handsets that have this defaulting to 'on' out of the box?