What Is Image Stabilisation?

Discussion in 'Casual Photo Conversations' started by https://www.blvdartists.com/, Nov 6, 2017.

  1. Not a problem with Sony/Canon.
     
  2. _DSC2730.jpg In my day, image stabilization involved the treatment of silver prints with a platinum solution. The platinum replaces the silver, and ia virtually immune to chemical attack, in addition to imparting a rich, warm tone to the print.

    Now that we are beyond all that, image stabilization in cameras and lenses uses accelerometers to detect camera motion, and moves the sensor (IBIS) or elements in the lens to counteract that motion. There is no reason either or both cannot be used in a DSLR, since the sensor is usually not used to detect motion. There is an exception where digital stabilization is used, in cell phones and simple video cameras.

    In-body image stabilization ((BIS) works best on shorter lenses, but can be effective on any lens compared to hand-holding alone. On the average, camera shake is about 2 deg/sec. The 1/F rule of thumb results in uncertainty in the film plane roughly equal to the full for depth of field - just below detection by the unaided eye in an 8x10" print held 10" from the eye. The largest part of camera shake is tilt and yaw. Lesser factors are rotation, vertical and horizontal translation (5 axes). The longer the lens, or the closer you go, the greater the effect of camera shake. The greater the effect at the film plane, the more displacement of the sensor is required to counteract it. It takes less physical displacement for optical image stabilization, which is shy longer lenses tend to incorporate IS in the lens. Some shorter lenses use it too, but it adds relatively more bulk and cost.

    Sony and Olympus are the only cameras that use IBIS, to my knowledge. I have a Sony A7Rii and A9, in which IBIS and lens IS are highly effective. Sony advertises 5.5 stops of stabilization, compared to the 1/F rule (200 mm = 1/200 sec minimum). I have one test with a 200 mm lens which lends credence to this claim.

    Sony A9 + Sony 70-200/4 at 1/5 second
    View attachment _DSC2735 Detail.jpg

    View attachment _DSC2735 Detail.jpg
     
    Last edited: Nov 14, 2017
  3. While I appreciate stabilization in longer lenses >80mm, I am rather in agreement with Ilkka on this. I have a stabilized 16-35mm, and to be honest I think it does not add much extra to the lens. One can easily handhold a 16mm lens at 1/60th and get sharp results. The IS allows me to hand hold at 1/15th, but then human and any moving elements are blurred, so I probably will not like the result, so it is no advantage. The same applies even with a 35mm lens: 1/60th will be nice and sharp with IS, but moving objects will not be. Stabilization is very useful with longer lenses when high shutter speeds such as 1/1000 sec are needed to ensure freedom from camera shake, but for normal and wides, I am not really convinced of the necessity.
     
  4. The 1/F rule is a bare minimum. To get pictures sharp at the (nearly*) pixel level, you have to shot 3 or 4 times that fast.That's where image stabilization proves useful, especially for landscapes. A 16 mm lens at 1/60 would fall in the "safe" category. It is also useful in low light, even with short lenses. Even though people may move enough to blur in a longer exposure, it's not particularly difficult to catch them at relatively stationary moments. You just have to take more shots and hope for the best. Camera shake, on the other hand, is always there, and doesn't change much even if you concentrate.

    * I say "nearly" because IS seems to impart slight disturbances at best, and if used on a tripod, very noticeable disturbances. With both IBIS and optical stabilization at my disposal, and the Sony does not produce noticeable artifacts described in the previous sentence, I rarely use my Sony cameras on a tripod, and then mainly for consistency or hand-free operation, rather than ultimate sharpness.
     
  5. Most fairly recent IS Canon lenses can sense if the lens is tripod mounted and switches off the IS, or at least Canon do not feel it necessary to say anything about it, but the earlier Canon IS systems were suggested to be turned off. It is advisable to read the instructions for each lens in this regard.

    I am not a slave to "ultimate sharpness" which I generally think is a never ending and rather pointless pursuit, but in general I do like an suitably sharp image when required.
     
  6. Sony a9 with FE 100-400mm f/4.5-5.6 GM OSS, at 400mm, 1/60-sec. handheld, with no IS

    [​IMG]Untitled by David Stephens, on Flickr

    Same rig, with IS on:

    [​IMG]Untitled by David Stephens, on Flickr

    I couldn't turn off IS at the lens and keep IBIS on. As someone wrote early, apparently they split duties.

    Later in the week, I'll mount a Canon lens and try it with no IS, lens IS only, IBIS only and both lens and body IS engage.
     
    marc_bergman|1 likes this.
  7. Actually, at least with my EF 500mm f/4L IS II USM, the IS stays on when on the tripod. With a big lens like that, even on a heavy tripod, with heavy ballhead and Sidekick, you can see the image settle down when the IS spools up. There's no need to turn it off.

    I've had people look at some of my 1,000mm handheld moon shots and claim that they see a half-pixel smear. For enjoyment of the shot that doesn't matter. OTOH, I have a 50" print of the Grand Canyon in my office. Most people stand six-feet away and love it, but photographers put their good-eye six-inches away and then they approve, the sharp results from low ISO, tripod mount and remote release. Still, most of my landscape shots are handheld, but with ISO engages.
     
  8. I spoke too bradly about the effect of using IS on a tripod. I have not noticed any artifacts with my Sony and Sony/Zeiss lenses. However when I used my original Nikon 70-200 AF-S IS on a Nikon D3 (or earlier), the image would drift slowly and sometimes jerk at the moment of exposure. That lens uses gyroscopic acceleration sensors, which apparently have a tendency to precess. Linear inertial accelerometers do not exhibit precession.
     
  9. My single most expensive lens lacks in-lens stabilization, but I also don't consider it a useful feature for that particular lens(14-24mm 2.8).

    BTW, here's one person's take on the value of VR. Thom Hogan is pretty well respect in the Nikon community, and his basic advice is to only use VR when you need it

    All About Nikon VR | DSLRBodies | Thom Hogan

    I think the Canon system is similar enough that we could likely extrapolate much of what he says to IS.

    BTW, VR isn't infallible, but it can help. As an example, at ~50mm(full frame) I can often get about every other shot or every third shop acceptably sharp down to about 1/15 or maybe a bit slower. I could never do that without VR, but it also means firing a couple of shots to be safe. Also, if I'm doing something like chasing kids around inside, those kind of shutter speeds mean that I'm probably going to have sharp furniture and blurry kids :)
     
  10. What is the downside, other than use in conjunction with a tripod?

    You can keep the subject sharp while blurring the background by panning in IS mode 2. It's pretty obvious that a subject in motion is likely to be blurred at a slow shutter speed, VR or not. That merits repeated shots in order to capture a pause in the motion. VR is not infallible, even with stationary subjects, if you don't use a modicum of technique. If you are accustomed to whipping your camera to and from your eye, you might want change that behavior..
     
    dcstep likes this.
  11. I didn't want to confuse things, so I didn't show it in my examples above, when one of my 400mm, 1/60-sec., IS-off shots turned up sharp. This is not unusual. When shooting the moon, handheld, with IS on, I'll take several shots, in rabid succession and, almost invariably, there'll be one sharper than the others.
     
  12. Sandy Vongries

    Sandy Vongries Moderator Staff Member

    There are "Other Shots" for that problem! :D
     
    Last edited: Nov 15, 2017
    dcstep and Norman 202 like this.
  13. There's no need to turn it off.

    Yes, the 500mm is one of the more recent IS systems, and I suspect the instructions don't suggest turning it off. I seem to remember the 70-200 f4 IS did suggest turning it off when on a tripod, and I noticed a small improvement with that lens, but all of this is dependent on whether you think the improvement you get from reducing tripod vibrations, wind etc is more beneficial than removing any IS-induced vibration. I am sure with a 500mm the former would virtually always win out anyway.
     
    dcstep likes this.
  14. If you slowly move the lens in one direction, at some point IS will get to its limit, and there is a jerk as it recenters.

    This also means turn IS off while panning for moving objects.
     
  15. Not with Sony or Canon.
     
  16. Random motions due to hand shake keep the IS mechanism active and centered. I have noticed instability as you describe, but only in systems at least 10 years old and only on a tripod. Many IS lenses, have a mode switch with two settings. One setting has milder action which results in less jerky action in the viewfinder and permits smooth panning. The other mode is more aggressive, and has equal stabilization in all directions. Sometimes seeing stabilization in the viewfinder is optional. I can sometimes see IS action in my Sony A9 as jerky motion when I pan quickly between objects which aren't moving with the camera. That's an extreme condition visibly only because od raw EVF no-blackout properties. I never see any artifacts in normal operation.
     
  17. If you move constantly in one direction, the system can't keep up forever.

    It works well for vibrations around the desired aim.

    I suspect that a high-pass filter, allowing it to ignore slower motion, helps.

    But if you quickly move only in one direction, and for long enough, something has to happen.

    If the logic figures out that you are panning a moving object, it might just give up trying to correct for it.

    But it is hard to tell, looking though the viewfinder, moving that fast.
     
  18. I haven't noticed that with my a9. Is it happening to you with an EF lenses or FE?

    When I'm shooting with my FE 100-400mm, with electronic shutter, tracking a fast bird, I'll notice a fluttering in the EVF. I've assumed that was the actual images going by at 20-fps, with the in-between view being the EVF between shots. I've never thought to track a bird without shooting. I'll do it when I'm out this evening, to see if I can notice anything.
     
  19. I quite often pan nearly 180-degrees. I've never noticed an issue. That's usually not level panning, but sometimes it is.
     
  20. I might be seeing a stroboscopic effect due to the refresh rate of the EVG - 120/sec. The stills are sharp and video is steady, even during rapid panning. There is none of the jerky motion I used to observe with my Nikon D3.
     

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