Camera makers often say their in-body stabilization, whether it’s optical stabilization, digital stabilization or both combined, can deliver ‘gimbal-like’ steadiness.
That’s sometimes true, up to a point, for a certain style of shooting, but the fact is that stabilization and gimbals are two completely different things that work on two completely different principles.
A gimbal is designed to keep the camera still and, if you make a deliberate movement, to carry it out smoothly, in effect disconnecting the camera’s movement from your own.
An image stabilization system does not and cannot stop camera movement. All it can do is try to compensate for it by instantaneously shifting the sensor to counteract the movement and keep the image stable on the sensor, shift optical elements within the lens to achieve the same thing or, in the case of video, use digital stabilization to shift successive video frames to compensate for any shifts in viewpoint with camera movement.
It might sound similar, but it’s not.
In stills photography, stabilization is extremely effective. You’re capturing an instantaneous moment in time and all that matters is that the image doesn’t move on the sensor during the exposure. It scarcely matters whether this is achieved with a tripod, a high shutter speed or an image stabilization mechanism in the camera or lens.
With video it’s very different. Image stabilizers can still be very effective if you are filming from a fixed, static position. Your footage can look as still and steady as if it was shot on a tripod.
The trouble starts when you start to introduce deliberate camera movements, such as a pan, a low-to-high ‘crane’ shot or run and gun filming while walking.
Image stabilizers cannot deal with this anywhere near as effectively as a gimbal. The very best might be able to smooth out a slow pan or crane shot, but it will take some handling skill on the part of the operator and it’s probably not going to look perfect. Steady run and gun shooting with stabilization alone is extremely difficult and takes a lot of skill, practice and even luck.
Gimbals aren’t just about stabilization
A gimbal, however, makes smooth movements like these something that even beginners can achieve. And professionals rely on them too, partly because they can’t afford to keep re-shooting a clip to get one that’s ‘steady’ – it needs to be right first time – and partly because gimbals do a whole lot more than keep the camera steady.
- Gimbals ‘damp’ the operator’s movement. If you pan too fast the video will start to look jerky rather than smooth, and judging the right panning speed is difficult do manually. A gimbal, however, will pan at its own speed, not yours. If you pan too fast, the gimbal’s pan motor will slow down the camera movement and catch up with you at its own speed. You get smooth pans even if you’re bad at panning.
- Gimbals can keep the camera horizontal. Skewed horizons in video look awful and they’re not so easy to fix, especially when the angle of the skew changes during the clip. Gimbals have gyros which can keep the camera and the horizon level whatever angle you’re holding the gimbal at.
- Gimbals offer other ‘follow’ modes. You can lock the horizontal axis as above to keep the camera level, but you can also lock the tilt axis so that it doesn’t look up or down but stays horizontal – perfect for ‘crane’ shots. Or you can switch to an FPV mode that follows your own movement, including tilts, but still smooths the camera movements.
- Gimbals offer controlled camera movements, even by remote control. This varies according to the gimbal, but even my basic Ronin SC can do remote control panning movements controlled from its smartphone app.
Comparing stabilizers to gimbals only works if you ignore all the other things gimbals can do beyond simple stabilization.
Stabilization systems have limits and weaknesses
One is that they can’t smooth or damp out fast camera movements. There is simply not the range of movement needed in the stabilization system. The best they can do is fix ‘jiggling’ and wobbles. If you pan the camera too fast, it’s still going to be too fast even with a stabilizer. In fact, what I see a lot with in-body stabilization systems and fast camera movement is a kind of ‘jump reset’ where the footage is not shaky, exactly, but jerky. I take this to be the sensor continually re-centering whenever it runs out of movement.
Image stabilization systems can’t keep the camera level while filming. They can’t restrict the camera movement axis to pans or ‘crane’ shots. They don’t let you control camera movements remotely (obviously).
Stabilization systems can also introduce artefacts you don’t get with a gimbal, and it all comes back to that initial point…
An image stabilization system does not and cannot stop camera movement. All it can do is try to compensate for it.
One obvious restriction is with digital stabilization systems. These work well but come with a crop factor that reduces the angle of view of the lens. That’s because they need ‘spare’ image area around the frame for the frame-by-frame shifts this system uses.
But compensating for camera movement can also introduce artefacts that can’t be edited out.
- Parallax ‘wobble’. This isn’t a real term, just one I’ve invented. It happens when you are close to your subject with a wide lens. Every time the camera shifts, the parallax changes, and your subject’s position relative to the background changes. It needn’t be much, but it still shows. The stabilization system might keep your subject fixed and steady, but then the background can appear to ‘jiggle’ or ‘wobble’.
- Rolling shutter. Most mirrorless cameras exhibit some degree of rolling shutter, where fast movements can make objects skew and distort. It’s because they have to read the sensor in ‘strips’ rather than all at once. This will be be exaggerated badly by fast camera movements, which in-body stabilizers can only counteract up to a point.
- Edge wobble. As with ‘parallax wobble’ this can become noticeable with wider lenses, and with run and gun style shooting. Camera movement with wideangle lenses can produce very high angular velocities (sorry, I used to study physics) with objects at the edge of the frame, which is going to provoke a rolling shutter effect.
All of these issues are caused by camera movement and they cannot be fully corrected by stabilization systems. It’s like shutting the stable door after the horse has bolted.
Stabilization has its place
Of course it does. It can be very good indeed at steadying up the camera for static filming, and it can also smooth out slow and controlled camera movements – but this takes some skill and a good understanding of your camera’s limits, and those of its stabilizer.
But for camera makers to say their systems offer ‘gimbal like’ stabilization is a bit of a stretch. They don’t. They go some way towards a gimbal’s performance in certain situations, but don’t do half of the jobs that gimbals are made for.