I have been asked a question via PM, when to use and not to use IS. That could have been a couple of sentences answer, but I have had many conversations with other photographers where, although they were near enough right with the use of IS, they didn’t really understand what or why. So I thought a more in depth answer may be of some benefit to other Forum members.
Why the need for Image Stabilization?
The human body is always moving …………. assuming you are not deceased! That is through voluntary movement, breathing and involuntary movement, which the body is always subject to. If you use a slow shutter speed, these voluntary and involuntary movements will cause your images to be unsharp. Before Image Stabilization, the advice was to use a tripod, or use a shutter speed at least the reciprocal of the lens you intended to use. So, for a standard 50mm lens the reciprocal would be a minimum shutter speed of 1/50thsec or above. A 200mm lens would need 1/200thsec or above and a 500mm lens would need at least 1/500thsec or above. Note that a 500mm lens needs 10x the shutter speed of a 50mm, because the higher magnification of the 500mm also magnifies the amount of camera shake by a factor of 10.
How does Image Stabilization work?
Image stabilization is designed to minimize camera shake, but it cannot eliminate it. There will still be occasions when you need to use a tripod and a remote release. Early systems could minimize camera shake by two stops, so for example if you were using a 200mm lens, instead of needing 1/200thsec under the reciprocal rule, using IS you could get away with 1/50thsec. The newer IS systems claim up to four stops and that would mean a minimum shutter speed of around 1/15thsec, though I haven’t actually tried it. At that speed I would already have the tripod out.
There are two types of IS: in-camera and in-lens and in my opinion, in-lens is superior, because each lens can be optimized for best performance, whereas in-camera is a compromise for all of the lenses that could be used on that body. It works by using two small gyroscopes within the lens, one to minimize horizontal movement and one to minimize vertical movement. If you are panning a subject, you can switch off the horizontal gyro so that only the vertical movements are corrected. Early IS systems could also provide soft images if IS was switched on, but the camera was on a tripod. The IS was trying to correct camera shake when there wasn’t any present and by default, sometimes introduced some shake into the shot. Later systems have electronics that detect when camera shake is not present and switches it off.
When to use Image Stabilization?
This is to answer the original PM: when to use it and when not to. These are my thoughts, although I am aware that many keep it switched on all the time ………. just in case!
By its very nature, IS mitigates camera shake and has no effect whatsoever on the movement of the subject. My photography is mostly birds in flight and generally, I am using a shutter speed between 1/1,000thsec and 1/2,000th sec. Probably more for Kingfishers, humming Birds etc. So, for a 500mm lens, my shutter speed is well above the threshold for the reciprocal of the lens, so I switch IS off. What’s the point of trying to correct a problem that isn’t there? Equally, any fast sports action, motorsport and fast jets I will not use IS. For propeller driven aircraft I want some prop blur, so I will bring the shutter speed down to 1/250thsec to get a few shots in the bag and once that is achieved, I will adjust the shutter to 1/125thsec and maybe 1/60thsec for even more prop blur. Because all of those shutter speeds are below the reciprocal of the lens, IS will be switched on. The same with some motorsport shots where I want the body sharp, wheels blurred and motion blur in the background. I also have IS switched off when using a tripod, beanbag, or monopod.
Conclusion
I hope I have answered the original question and the above is of some use to other members. May I advise that these are only my thoughts and I may well be wrong on some aspects. If so, I am more than happy to learn from you.
Why the need for Image Stabilization?
The human body is always moving …………. assuming you are not deceased! That is through voluntary movement, breathing and involuntary movement, which the body is always subject to. If you use a slow shutter speed, these voluntary and involuntary movements will cause your images to be unsharp. Before Image Stabilization, the advice was to use a tripod, or use a shutter speed at least the reciprocal of the lens you intended to use. So, for a standard 50mm lens the reciprocal would be a minimum shutter speed of 1/50thsec or above. A 200mm lens would need 1/200thsec or above and a 500mm lens would need at least 1/500thsec or above. Note that a 500mm lens needs 10x the shutter speed of a 50mm, because the higher magnification of the 500mm also magnifies the amount of camera shake by a factor of 10.
How does Image Stabilization work?
Image stabilization is designed to minimize camera shake, but it cannot eliminate it. There will still be occasions when you need to use a tripod and a remote release. Early systems could minimize camera shake by two stops, so for example if you were using a 200mm lens, instead of needing 1/200thsec under the reciprocal rule, using IS you could get away with 1/50thsec. The newer IS systems claim up to four stops and that would mean a minimum shutter speed of around 1/15thsec, though I haven’t actually tried it. At that speed I would already have the tripod out.
There are two types of IS: in-camera and in-lens and in my opinion, in-lens is superior, because each lens can be optimized for best performance, whereas in-camera is a compromise for all of the lenses that could be used on that body. It works by using two small gyroscopes within the lens, one to minimize horizontal movement and one to minimize vertical movement. If you are panning a subject, you can switch off the horizontal gyro so that only the vertical movements are corrected. Early IS systems could also provide soft images if IS was switched on, but the camera was on a tripod. The IS was trying to correct camera shake when there wasn’t any present and by default, sometimes introduced some shake into the shot. Later systems have electronics that detect when camera shake is not present and switches it off.
When to use Image Stabilization?
This is to answer the original PM: when to use it and when not to. These are my thoughts, although I am aware that many keep it switched on all the time ………. just in case!
By its very nature, IS mitigates camera shake and has no effect whatsoever on the movement of the subject. My photography is mostly birds in flight and generally, I am using a shutter speed between 1/1,000thsec and 1/2,000th sec. Probably more for Kingfishers, humming Birds etc. So, for a 500mm lens, my shutter speed is well above the threshold for the reciprocal of the lens, so I switch IS off. What’s the point of trying to correct a problem that isn’t there? Equally, any fast sports action, motorsport and fast jets I will not use IS. For propeller driven aircraft I want some prop blur, so I will bring the shutter speed down to 1/250thsec to get a few shots in the bag and once that is achieved, I will adjust the shutter to 1/125thsec and maybe 1/60thsec for even more prop blur. Because all of those shutter speeds are below the reciprocal of the lens, IS will be switched on. The same with some motorsport shots where I want the body sharp, wheels blurred and motion blur in the background. I also have IS switched off when using a tripod, beanbag, or monopod.
Conclusion
I hope I have answered the original question and the above is of some use to other members. May I advise that these are only my thoughts and I may well be wrong on some aspects. If so, I am more than happy to learn from you.
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