Behind image stabilizer lenses and the Canon EF 70-200mm IS USM
Image stabilizers are helpful fancy additions to zoom lenses. In high zoom factors every tiny camera movement is translated to a blurry photo. There are different techniques to avoid such movement but sometimes when taking photos fast without a tripod or special equipment an image stabilizer lens might be the only way to go. Here is how and why.
There are different techniques you can use to eliminate camera movements. For example, you can hold the camera against a steady surface such as a table, a wall, a bench or a light pole. To make sure that the surface is indeed stable try to shake it a bit with your hand. When holding the shutter down and taking the photo apply some force on the camera pushing it toward the surface to make sure it is completely stable.
Another technique to eliminate movement is by simply placing the camera on a horizontal stable surface. The surface needs to be flat and stable. When you shoot the digital photo you should gently press the shutter button making sure that the camera does not move and then let go. One problem with this method is that the camera might shake or bounce when you press the shutter button. You can overcome this by setting the camera to delayed shutter, set the camera to timer mode with the shortest time, 2 seconds is typical. Another option is to use a remote control if your camera supports one and you have it handy.
Image stabilizers are special electro-mechanical devices that are install in zoom lenses. There are basically two types of image stabilizer one that moves the sensor and one that actually uses gyroscopes in the lens to move a floating optical element that compensates for shakings. The latter is more expensive and provides better results. For many years image stabilizers were available in expensive professional cameras. In the last few years a few manufacturers including Canon introduced image stabilizer enabled zoom lenses in a price range that is affordable to amateurs and semi-professional photographers.
Lets look at the Canon EF 70-200mm f/4L IS USM lens as an example. The Canon EF is compatible with Canon SLR cameras such as the Canon EOS. The lens offers auto-focus zoom. The Canon EF uses a gyro based image stabilizer to compensate and eliminate unwanted camera movements.
Image stabilizers also have drawbacks. When trying to take photos of fast moving objects you might need to intentionally move the camera. Such erratic movements can confuse the image stabilizer mechanism that will in turn either under-compensate or over-compensate. Canon EF tries to solve this by enabling a few different stabilizer modes. In Mode I it corrects movements along both horizontal and vertical axes. If however you are trying to take a photo of a horizontally moving object by panning the camera to the left or to the right, Mode II will disable the vertical axis to prevent unwanted stabilizer side effects.
Another reason why zoom lenses tend to be more sensitive to shakings in addition to the zoom factor is their weight. Zoom lenses are big and heavy. The Canon EF weighs about 26.8 ounces. Such a weight leveraged by its horizontally position far from the hands makes holding the camera stable even harder. Having an image stabilizer is almost a must with such lenses.
Danette Mckay explains more about many subjects on canon ef 70-200mm f/4 l is usm lens for canon digital...