Image Stabilization (IS) is one of the features a lens might or might possibly not have. When available (and turned on) on your lens, it will keep image blur due to camera shake to a minimum, and it will enable you to shoot with slower shutter rates of speed while maintaining sharp focus.
It's important to bear in mind that image stabilization will not solve blurry image problems if the motion is caused by your subject moving rather than you handholding the camera, or by extreme camera movement at and during exposure.
Image stabilization might permit the use of shutter rates of speed 2-4 stops slower (exposures 4-16 times longer) than otherwise possible, and occasionally more.
To calculate the slowest shutter speed that is possible for a instant camera with no noticeable blurring of the image, it needs to be 1/lens focal length you're shooting with.
This means that if you're shooting with a 50mm lens, your minimum shutter speed should be no longer than 1/50, for example 1/50, 1/60, 1/125, 1/250… etc to avoid image blur.
Likewise, if you're shooting with a 70-200mm contact lens at let's say 125mm focal length v guard vg 400 , your minimum shutter speed should be no longer 1/125, for example 1/125, 1/250, 1/500… etc. If you are lens offers image stabilization, you could take the slowest shutter speed possible down an extra 2-4 stops and up. This means you could shoot at 1/15 or 1/8 or even slower, with no significant image blurring. This is of course assuming you have a 35mm format camera.
If you're not using a 35mm format, you need to note that the harvest factor will affect the slowest shutter speed possible at a given focal length.
The harvest factor, also known as the focal length multiplier (FLM), is the relation of the dimensions of a camera's image aircraft compared to a reference format. Most often, this term is applied to digital camera models, relative to 35mm film format as a reference. In the case of digital camera models, the image aircraft would be a digital sensor.
Taking that under consideration, let's assume you're shooting with a 1. 6x harvest factor image aircraft at 50mm focal length. Your actual focal length would then be 50 X 1. 6 = 80mm rather than 50mm. So the slowest possible shutter speed that won't result in image blurring while handholding your camera would be 1/80s or faster.
Image stabilization names change from one manufacturer to another, but they all serve the same purpose and do the same job:
Cannon
IS (image stabilization)
Nikon
VR (vibration reduction)
Sony Cyber-Shot
Optical SteadyShot
Sony
SSS (Super Steady Shot)
Panasonic or Leica
MegaOIS
Sigma
OS IN THIS HANDSET (Optical Stabilization)
Tamron
VC (Vibration Compensation)
Pentax
SR (Shake Reduction)
It's important to bear in mind though that image stabilization is not an alternative for a tripod, and that its considerably better keep it off when it's not needed (when you're already shooting at high enough shutter rates of speed or when it's setup on a tripod). Doing so will also lengthen your battery life since IS draws more power supply.
Most manufacturers do claim that the IS feature of a lens be put off when the lens is attached with a tripod as it can certainly cause unexpected results, and is generally unnecessary.
Many modern image stabilization contact lenses are able to detect when and when not your camera is being attached with a tripod, due to significantly low vibration tellings. A great example of those are canon's newest IS contact lenses.
When extremely low vibration is detected, those contact lenses are designed to automatically disable image stabilization on their own.
Image stable contact lenses also have disadvantages. One main problem would be the high price tag that goes along with them. Image stable contact lenses can also yield poor bokeh results due to light shifting from its true optical path while passing through the lens, something you might be concerned about.
