May 16, 2008

In Today's One Minute Astronomer...

Binoculars (Part 3)

Although they are expensive, imaged-stabilized (IS) binoculars give stunning low power views of the sky without the dreaded image shake of standard binoculars. It's hard to read a review that doesn't rave about these technical wonders for astronomy or terrestrial use.

--- Highly Recommended ---

The "ultimate guide" to choosing a telescope, binoculars, and astronomical accessories. Don't buy your optics before you read this essential resource. Now in it's fourth edition. Learn more...

-------------------------------

The Basics

• Nikon, Canon, and Fujinon, among others, offer some type of image stabilization. Canon models seem to have the widest following among amateur astronomers.

• Piezoelectric motion sensors detect the pitch and yaw movements in the binoculars. The motion signal feeds into a microprocessor, which initiates image stabilization by controlling a vari-angle prism - a pair of glass plates joined by flexible bellows. The space between the plates is filled with a silicon-based oil to maximize image deflection.

• The motion sensors work in light or total darkness and operate at any orientation, so there are no restrictions on where the binoculars can be pointed… up, down, sideways, anywhere.

A Deeper Look

• When you switch on the IS feature, the image does not “freeze”, but rather wanders slowly enough for your eye to follow. And the IS works when you sweep across a field of view, although there is a slight hesitation.

• These devices are battery hogs. You can burn through a pair of alkalines in 5 minutes on a cool night. With rechargeables, you might get 2 hours. Of course, you can turn off the IS feature when you're not using it.

Good To Know

In a 2006 review of Canon's 10x42 IS binoculars, Gary Seronik said “These are simply the finest binoculars I have ever used for astronomy”.

Personal View

Image shake in regular binoculars led me to abandon binocular astronomy many years ago. But one look through Canon's small 10x30 IS rekindled my interest in binoculars. If you have dark-sky and if you can afford a pair of IS binoculars, I highly recommend them.