HoloLens is a virtual-reality headset you don, a little like the VR headsets that Samsung, Oculus and others have been making except this one lets you see the virtual world, and the real world, both at the same time. Where those other devices transport you wholly and often very convincingly into a different place, the HoloLens is more like a heads-up-display, superimposing the virtual world onto the place you're really in.

And, right now, it's far less convincing than the other VR headsets, but nevertheless just as astonishing.

I got to use a HoloLens device for about two hours, in a workshop designed to show software developers how they can add regular Windows 10 applications to a HoloLens headset and turn the apps into hologram-like objects that appear to exist in the world.

The main thing I noticed, apart from the weight of the device and the way it tangled in my hair (for which I blame my hair more than the HoloLens itself), was this: viewing videos of what it's like to use a HoloLens is very different from actually using one.

A video camera filming through a HoloLens display has no peripheral vision - it has only the 16 x 9 rectangular aspect, which it translates to the screen you watch the video on. So watching a video of HoloLens in action, you don't notice that the HoloLens itself has no peripheral vision, either.

But when you actually wear one, you notice it immediately. When the HoloLens projects images onto the glass in front of your eyes so that they appear to be in the real world, it only projects them in a rectangle right in front of your eyes. Above, below and to the sides of the rectangle, there are no holograms, meaning you have to hunt around with your head until you are looking directly at a hologram before you see it.

Worse than that, the objects are clipped as they move in and out of frame. As you turn towards one, the edge of the frame cuts through it - on one side of the edge, the object is there, on the other side of the edge, the object is not there - dispelling the illusion that the holograms actually are objects in the world, and not just videos in the HoloLens.


It's disappointing, because other than that, the HoloLens is astonishing, and a feat of engineering. If Microsoft can widen the field of view - which hopefully it will do in later releases of the HoloLens, which is still in the development stage - it could change the world.

When you're wearing the HoloLens and looking at a hologram, the hologram stays locked in its position despite almost everything you do. You can physically walk around the hologram, and it stays put just like any other object in the real world. You can look under it, look at it from above, and it doesn't budge an inch. That's a remarkable trick, considering its position in front of your eyes is constantly being calculated and recalculated, based on your slightest head and body movements.

The only way I was able to get the holograms to glitch was to walk right up to them and basically stick my head in them (virtually speaking), at which time they start to disintegrate the way objects in video games used to, when you accidentally walked your character through a wall or through another character in the game.

Or I could trick the HoloLens by turning away from a hologram, and quickly turning my head back to catch it by surprise. Then it would be floating in space for a beat or two, before it realised I was looking at it and quickly fixed itself back into its real-world position.

It's like something out of the Matrix, only, well, it's a little too much like the Matrix. When you watch that movie on your TV, it's stuck inside that 16 x 9 box, too.

John Davidson attended the workshop in San Francisco as a guest of Microsoft.