| If you have not yet purchased an image stabilizing | | | | compensate by telling the motors to drop the |
| lens, you might nonetheless have heard the term | | | | floating lens elements down a little to maintain the |
| "image stabilization" or "vibration reduction" bandied | | | | optical path of light traveling through the lens |
| about in reference to various point-and-shoot | | | | elements. If the lens body is rotated to the left, |
| cameras and SLR lenses. In that case you | | | | the lens elements shift to the right to |
| probably understand that IS or VR technology | | | | compensate. The end result is that the image |
| supposedly results in sharper images. But does | | | | maintains its position on the image sensor during |
| the technology really work, and how well? What | | | | the exposure, creating a much sharper image |
| actually happens to make it work? In what | | | | than if the vibration reduction system had been |
| situations does it not work at all? And most | | | | deactivated (which it can be). |
| important of all, do you really need it? | | | | It might seem remarkable that the system can |
| The answer to the first question is yes, image | | | | track camera shake so well. In fact, it is |
| stabilization technology not only works, it works | | | | remarkable, but it all works because camera |
| well. If it did not, the remainder of this article | | | | motion can be monitored about every 1/1000th |
| would be entirely unnecessary. But it is useful to | | | | of a second, while the camera wobble occurs on |
| understand exactly what image stabilization is, and | | | | a time scale of, say, 1/30th, 1/15th, or even 1 |
| when it can be used to improve your | | | | 4th of a second. |
| photography before you shell out the extra few | | | | Vendors of these image stabilizing lenses claim |
| hundred dollars for a lens that has IS built into it. | | | | that the technology allows you to gain about 3 to |
| Note: While the term "image stabilization" is used | | | | 4 stops on your exposures. This means that if, |
| more frequently by writers when discussing this | | | | for a given photographic situation, the slowest |
| topic, "vibration reduction" is the term that Nikon | | | | hand-held shutter speed that consistently results in |
| uses to describe the same feature in its lenses, | | | | an OK image is 1/125th of a second, then by |
| and it also happens to better describe what is | | | | adding vibration reduction you ought to be able to |
| going on. You should consider the two terms as | | | | shoot at 1/15th or perhaps even 1/8th of a |
| interchangeable. | | | | second. This is a big deal if you are forced to |
| To understand how vibration reduction works, | | | | shoot into shadow, or the light is fading, or you |
| let's consider for a moment the effect that it | | | | need to close down the aperture to improve |
| corrects for. When a camera is hand-held, and the | | | | depth of field. |
| shutter is open for a duration longer than the | | | | But image stabilization only proves itself in a range |
| camera can be pointed in one direction without | | | | of shutter speeds that are neither too great, nor |
| moving, then the resulting image is seen to be | | | | too small. If you try to hand-hold a 1 second |
| blurred. What happens is that as the camera lens | | | | exposure it's unlikely your VR compensation will |
| tilts upwards, sideways, or a combination of the | | | | be able to keep up with the erratic motions you |
| two, the focused image shifts position on the | | | | supply it. Likewise, if you are shooting at 1/500th |
| image sensor. A focused point of light ends up | | | | of a second or higher, the camera won't have a |
| being rendered as a line. The accumulation of all | | | | chance to experience any wobbling, so the VR |
| the shifted points of light that make up an image | | | | system will not add any improvement. |
| results in a blurred image. | | | | Another thing to remember about vibration |
| The obvious correction therefore would be to | | | | reduction is that it has to do with compensating |
| shift the image sensor by the same amount that | | | | for camera motion during exposure. It has nothing |
| each point of light is shifted, so the image and the | | | | to do with the speed of the object you are trying |
| image sensor move together in relative lock-step. | | | | to photograph. So that fast-moving baseball will |
| Some camera manufacturers implement this | | | | still be rendered as a blur unless you capture it at |
| exact solution, and float the image sensor so that | | | | 1/500th of a second. |
| it can track the image if the camera shifts during | | | | Do you need IS or VR lenses to improve your |
| exposure. But this is the exception, rather than | | | | photography? This one is fairly easy to answer. If |
| the norm. Generally the solution is achieved by | | | | you regularly find yourself shooting at speeds less |
| adding the vibration reduction to the lens, rather | | | | than 1/250th of a second then there is a very |
| than the camera body. | | | | good chance you can rid yourself of a substantial |
| So how does this work? Actually it is fairly simple | | | | number of those blurred, or unsharp, shots by |
| to understand. Instead of a floating image sensor, | | | | investing in a good VR lens. Better yet, when you |
| the lens body contains floating lens elements. The | | | | buy your next digital camera, simply go for a |
| position of these lens elements is controlled by | | | | point-and-shoot with vibration reduction built in, or |
| motors that are coupled to sensors which detect | | | | if you purchase a digital SLR, try to grab a model |
| how much the lens body is rotated vertically or | | | | with vibration reduction built into the supplied kit |
| horizontally during exposure. | | | | lens. |
| If the lens body rotates upward, the sensors | | | | |