OIS and IBIS are two competing technologies for image stabilization used in cameras. OIS stands for “Optical Image Stabilization” and IBIS stands for “In Body Image Stabilization”. Why IBIS is called IBIS is silly as it should be called MSIS or “Moving Sensor Image Stabilization”.
The reason for this deceptive naming of IBIS is that the idea of a moving sensor is worrisome to professional photographers who understand how tiny of a movement can lead to blurry pictures. In many if not all cameras with IBIS, the IBIS mechanisms will subtly lower image sharpness. This is because the compensation of movement is not perfect and sometimes movements will occur at varying speeds which cause the IBIS to worsen the shot overall vs not having IBIS at all.
IBIS is best when used at very low shutter speeds. At lower shutter speeds the IBIS system works better as it is generally better than no IBIS at all. However, where IBIS starts to show issues is at higher shutter speeds, and particularly, higher shutter speeds with telephoto lenses.
The problem that IBIS encounters is that camera shake at 200mm and higher is much harder to compensate for by moving the sensor. This is due to the magnification factor of the lens. When a telephoto lens is used, the angle of view is much smaller, this has the effect of increasing the magnitude of the movement seen by the image sensor. The problem only gets worse as the focal length is increased.
While a small shake of the camera when using a wide angle may produce a movement on the sensor of a couple millimeters, when using a telephoto such as a 200mm or 300mm lens, that same movement will be magnified by the zoom amount. If we compare a 50mm lens to a 200mm lens, the movement seen by the sensor will be 4 times greater when seen through the larger lens. So a 1mm movement at 50mm becomes a 4mm movement at 200mm.
This effect is why many professionals shy away from IBIS as they understand that when using large lenses such as a 500mm or 600mm prime, the net effect of enabling IBIS will be a loss in image quality 90% of the time.
It’s important to realize that not only is the magnitude of the movement increased, the speed of the movement is also increased. In other words, at 50mm, if it takes 1/10th of a second for camera shake to move 1mm, at 200mm it will take 1/10th for the same shake to move 4mm across the sensor.
The fact that not only is the magnitude greater, but the speed as well, simply comprises another difficulty for IBIS when dealing with long telephoto lenses. The sensor must be moved further in the same amount of time as the focal length is increased. As you might guess, moving the sensor around at high speeds has many issues.
Ultimately the sensor is being moved too much in an IBIS system when used with long telephoto lenses. It stops making logical sense for a variety of reasons, not the least of which is that the image circle of the lens must be ridiculously large for IBIS to work on a super telephoto, a foolhardy pursuit for the sake of stabilization…
OIS wins for longer focal lengths
While IBIS works by attempting to move the sensor within the camera body, OIS works by moving a lens element inside of the lens to counteract the shake of the lens.
While this all might seem arbitrary to a lay person, there are big differences in how the two technologies work.
There are a few reasons why OIS ends up being better than IBIS when used with telephoto lenses. The biggest is simply that in an OIS system the movement is handled on a 1 to 1 basis. Because of where the OIS is positioned in the lens, the system only needs to move the exact distance that the lens moves. On the other hand, when dealing with the movement on the sensor, as we discussed earlier, the IBIS system is subject to the magnification of movement wherein the sensor must be moved faster and further as longer lenses are used.
It is still harder to stabilize really long focal length lenses with OIS when compared to shorter lenses with OIS. This is just the physical reality of hand holding say a 50mm lens vs a large 600mm f/4 lens. When a long 600mm lens is mounted on the camera, the system comprises a 1st class lever, with your hand on the camera body the amount of movement at the end of the lever aka, the front of the lens, is increased relative to a shorter lens.
While these types of physical realities make OIS troublesome to implement on super telephotos, they make effective IBIS essentially impossible.
Another advantage of OIS is simply the goal of the system. When using OIS with a long lens, such as a 600mm, there is no pretension of using it for long exposures. The goal is simply to lower the camera shake enough that slower shutter speeds can be used.
As a rule the minimum shutter speed for a 600mm would be 1/600th of a second, while the safe minimum would be 1/1200th of a second. Those are very high shutter speeds. The goal of OIS is simply to allow lower shutter speeds of 1/200th – 1/300th of a second. At this OIS succeeds far better than IBIS does.
OIS vs IBIS for 70mm and wider lenses.
Where the two equalize and IBIS pulls ahead is at the wider focal lengths. OIS still works great though if you realize that the goal of OIS isn’t to allow 1 second exposures. IBIS can sometimes do that but in general OIS will have issues with 1 second exposures.
If you’re doing handheld night photography of buildings or landscapes using a wide angle lens, IBIS is an excellent choice as it is very good at handling very long shutter speeds such as 1-2 full seconds in some cases. OIS isn’t quite as good for this, but, if you’re photographing people in low light, that’s where OIS tends to come out on top. This is because, OIS seeks to lower the magnitude of movement thereby allowing slower shutter speeds to compensate for the light, while still using a fast enough shutter speed to handle the movement of your subject.
I think a lot of people who say that IBIS is superior are forgetting that while it is nice to be able to do 1 second exposures, that’s not going to work very well if you’re trying to get sharp pictures of people or animals that aren’t totally motionless.
Both technologies have their advantages and disadvantages, OIS will allow lower, but not shockingly low shutter speeds, and it works well with longer focal lengths. IBIS can allow shockingly low shutter speeds of 1-2 full seconds when used with a wide angle lens, but tends to struggle with focal lengths at 200mm and above.
OIS vs IBIS for video
The same realities apply to video as do for stills but the standard for video is lower. Even so, OIS ends up winning big when it comes to longer focal lengths. At shorter focal lengths the two are just about equal with OIS having the advantage when it comes to larger movements.
OIS + IBIS working together
Everything is better when we work together right? Some modern camera systems now allow combining OIS lenses with camera bodies that have IBIS, and the combined stabilization effect is increased beyond what just one or the other would be capable of. If you have an OIS + IBIS capable system then you have the best of both worlds and you don’t need to worry about which one is better.
Other capabilities and costs of OIS and IBIS
There are other obvious advantages of OIS and IBIS. One nice thing about IBIS is that in theory IBIS can be used to stabilize any lens whether it has OIS built in or not. In fact, on my R5 I can set the focal length that the IBIS uses and have accurate stabilization with an old manual focus lens from 50 years ago. That’s a really cool feature that makes IBIS desirable.
Since OIS is by definition in the lens, there’s no good way to add OIS to an old manual focus lens.
One downside of IBIS is more expensive cameras. IBIS mechanisms in larger sensor cameras require a special harness to hold the image sensor, as well as special cables to connect the now mobile sensor to the rest of the camera. There are magnets, electronics, gyros, and more that are all added into an IBIS capable camera. All this adds up to increased cost.
On the other hand, the investment required for an IBIS capable camera is saved in being able to purchase lenses that don’t have OIS. As long as you’re not shooting with telephoto lenses IBIS may be all that is needed for good stabilization.
One misconception people tend to have about IBIS is that it doesn’t have an impact on the optical design of the lens. This is actually untrue. IBIS does impact the optical design of the lens as the best lenses for IBIS have a larger image circle. In fact, some Canon RF lenses are designed to have a larger image circle than normal which gives them higher performance on IBIS capable cameras like the R5 and R3.
While many have and will continue to scream bloody murder about how great IBIS is, and others will retort with condescension that only OIS can work effectively on their super telephoto lenses, the moral of the story is that each technology has its strengths and weaknesses. But with their powers combined, the camera is capable of a level of stabilization that is previously unheard of.