Acrobatic Tree Swallows

Tree swallows are a study in fast and precise acrobatics. These aerial foragers, with their tiny bills, forked tails, white breasts and iridescent, green-blue back feathers, feed on flying insects all day long. They are impressive acrobats, twisting and turning in unison, not unlike the tight flight performance so ably displayed by the US Navy’s Blue Angels.

The tree swallows I found at a local park did occasionally come down from their fast and furious acrobatic flying and perch. I did not have my tripod, so it was a good opportunity to play with the image stabilizer (IS) on my 300mm lens.

Shutter Speeds for Hand Held Photography

There are many, many reasons why the photographs I take are not all tack sharp (see the post here.) however, shutter speed is probably the most likely cause of blurry photos. There’s a simple rule to remember for setting the lowest shutter speed possible for hand holding your camera. If you have a 600 mm lens, set the shutter for at least 1/600 of a second. If you have a 300 mm lens, set the shutter for at least 1/300 second, and so on.

My experience has been that I have to set the shutter speed much higher than the simple rule prescribes to get sharp photos when hand holding my camera, especially when I’m using heavy lenses. (Even the tiniest movements are magnified with long lenses.) Consequently, when I buy a new lens, I always make sure it has a built-in image stabilizer to help compensate for my shaky hand holding.

Using Image Stabilizer When Hand Holding the Camera

It would be nice if the image stabilizer on my lenses maintained the stability of the birds I’m photographing. But no, image stabilization doesn’t stabilize the movement of the subject, only the shakiness of the photographer.

Image blur most often occurs when hand holding the camera. The longer the lens, the more likely the hand held camera will shake, even minutely. The more the lens shakes at low shutter speeds, the more blur. Image stabilizers help to reduce the blurriness caused by hand holding camera movement by up to 2-4 stops.

Think about it. The capacity to detect the subtleties of minute and constantly shifting movement in a hand held lens and then make corrections instantly most certainly requires complex equipment and computer analysis to built right into the lens. NOTE:  Some camera manufacturers build the IS mechanism into the camera itself, not the lenses.

How Do Image Stabilizers Work?

The Canon website describes the lens based image stabilizer technology as follows: “Canon Optical Image Stabilizer technology uses miniature sensors and a high-speed microcomputer built into the lens. The sensors analyze vibrations and apply correction via a special stabilizing lens group that shifts the image parallel to the focal plane. Motion blur is canceled, resulting in a sharper image. With Optical Image Stabilization, it’s like gaining up to four stops.”

No wonder IS lenses costs so much more.

Keep the Image Stabilizer ON All the Time

Canon’s highly efficient IS system makes it easy to set it and forget it. The company has even invented a tripod detection system, so you don’t have to worry about turning off the IS when the camera is mounted on a tripod. Canon has also added extra stabilizer modes on their lenses that correct hand held movement when panning.

I leave the image stabilizer ON all of the time.  I personally can not think of an example when it did not work correctly.

Questions to Ponder About Image Stabilization

Is the image stabilizer useless at higher shutter speeds?  

Possibly. But it works in the background so smoothly that I’ve never had to shut it off as I increased the shutter speed. On my 300mm lens, I can definitely feel and hear when the image stabilizer mechanism is working. And I definitely hear and feel that mechanism less as the shutter speed is increased.

In fast moving situations, does the IS slow down the speed at which focus is locked down?

Absolutely! When I’m using a slower shutter speed, I feel and hear the IS mechanism going thru its corrections. I have to wait 2-3 seconds until these corrections are made before I am able to engage the shutter release. When your subject is moving fast, it is likely that you will set a fast shutter. The IS has to make fewer (if any) corrections at a high shutter speed, so focus lock down will not be delayed.