Action Photography - IS or not to IS?
Does IS even matter when shooting at very fast shutter speeds?
This article goes through the reasons as to why you should always keep IS on irrespective of the shutter speed you are working with when shooting action (not still subjects, though).
What is IS?
IS stands for “Image Stabilization” (a Canon term) and the same system comes under various names like VR (vibration reduction) or VC (vibration compensation), etc. What IS does for you is move an internal glass element of the lens in such a way that it cancels out the vibrations caused in the lens by handheld shooting. You must have heard that you need to shoot at at least 1/ shutter speed of the lens to get sharp images. But that is no longer true if you have a stabilization system on your lens. If you do, you will probably get away with sharp, shake-free shots even at 1/30s, hand holding a 200mm lens!
Now the issue is, the stabilization system on certain big lenses does take up quite a bit of battery power and also makes some noise during operation (noise isn’t usually observed in professional, expensive lenses). Again, the third party telephoto or portrait lenses that come without stabilization are MUCH cheaper than the stabilized versions from the camera manufacturers.
So would you go for a non-stabilized telephoto lens if you are going to shoot mostly high speed action at a few thousandths of a second? Would you get sharper shots? Here’s what you need to know:
Firstly, more often than not, not-so-sharp photos in high speed shots are caused by wrong focus rather than camera shake.
Does the image stabilizing feature of your lens help with focusing?
Of course it does! Imagine firing away at 7 fps with your DSLR with the focus in servo mode. The camera has got a split second to regain focus and track your subject in-between two shots.
The cross - and line - type focus points that keep the subject on focus need a stable subject to be able to focus dead on. They cannot retrieve information about focus and subject movement in a thousandth of a second while the image can be captured blur-free within that period of time.
What that means is, it is not important to eliminate camera shake not only when the shutter opens, but also when the camera is focusing in-between shots! For lenses like the 400mm, f/4 or f/2.8, it is very challenging for the camera to track a subject properly. It relies on YOU to provide the ideal conditions for appropriate focus, that is, contrasty surface and a stable lens with as little vibrations as possible such that there are no small random movements to throw the AF system on and off frequently.
I did some tests to confirm the above. Two images from two different sequences were shot at high speed burst mode of a DSLR with very good focusing capabilities. The lens used is a standard 70-200mm f/2.8 lens with the UV filter on to mimic general shooting conditions. The camera was set to track focus in-between consecutive shots. A concert presents the camera AF system with a very challenging situation as there is fast subject motion and low ambient light, changing frequently with time.
Camera settings for test images:
Evaluative/matrix metering + 1/3 EV
70mm, ISO 1600
1/320s @ f/3.5
Focus mode: continuous tracking AF
The results were close to what one should expect: A good number of images from the burst sequences were slightly out of focus when IS was switched off.
I don’t have a stabilized lens, what should I do?
If you have a third party lens without image stabilization, for example, some budget 70-200mm lenses from some manufacturers are optically very good but lack stabilization. There is nothing wrong with going for those.
They will obviously not offer you the comfort of having image stabilization though. With those lenses, you may sometimes end up having inaccurate focus while handholding. To get better results, you may consider getting a monopod for it. Also, maintaining a good, steady body posture is important while working with heavy lenses. That ensures you get consistent, good results even with non-stabilized lenses.
Note that the above discussion holds for portrait and telephoto lenses only. Wide angle lenses without stabilization will work very well in most situations and are not affected much by camera shake because of their wide field of view.
Again, if you are mostly shooting stationary subjects at high shutter speeds and do not use the servo tracking auto-focus mode a lot, a non-stabilized lens will do very well for you most of the time because you have enough time to let the focus lock properly and the fast shutter speed will prevent motion blurs.
One should remember that getting the focus right is always the first priority because focus cannot be improved in the post processing phase.
- Pratik Panda ( www.PratikPanda.com)
Photo credits: Pratik Panda.
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