Telescope Reviews: Need advice on mechanical quality of zoom binos

"10000000000% not recommended"

C'mon Jawaid; say what you really mean!

Welcome CuriousOne:

You have asked about the "mechanical quality of ZOOM binoculars."

THERE IS NONE!!! Yes, there are some who will give the old “What about the . . .” However, I’m not one to give Jack the Ripper a pass because he once helped a cripple across the street.

You have also received some very informative posts from some very informed observers. SO, to help you further if I can, I would like to SEE their years of practical observing experience and RAISE decades in the optical industry and repairing and collimating more binoculars than most bino executives have ever seen in a warehouse—including thousands of military units.

The following is from a monograph on binocular realities:

*****

12. ZOOM BINOCULARS AND OTHER CONCEPTS FROM HELL

There are many reasons to be even more aware of “ZOOM” binoculars! To the uninitiated the ability to “ZOOM” is a feature; to the serious observer they are anything but! For the most part, the zoom is made possible by the movement of an auxiliary system in the ocular (eyepiece) assembly of each telescope. The tubes move fore and aft along the optical axis by means of a small brass screw which passes through helical slots in the walls of the auxiliary tubes. When the zoom is operated, a series of spur gears move the screws to send the auxiliary lens systems back and forth.

As you may have guessed, there’s going to be a lot of lost motion. And, even if the lenses were flawlessly matched in curvatures, spacings, thicknesses and glass types, the lost motion in the zoom mechanism is usually bad enough (especially as the instrument begins to age) to degrade the image. Also, while the brain can compensate for small errors in collimation, it can’t compensate for differences in magnification. That means your binocular could be collimated exceptionally well and you still wouldn’t have a good image!

Another negative attribute of almost all zoom binoculars is that they produce smaller fields of view than their fixed-power counterparts at any given magnification. Some are so bad, one might get the impression he or she is looking through a pipe instead of an optical instrument!

Finally, the auxiliary systems that make zooming possible are seldom sufficiently blackened. This causes a scattering of light and a loss of contrast across the entire field of view. So, can I recommend a really good zoom binocular? All the really good ZOOM binoculars I know of are listed in the box below:

(small rectangular box)

And, if you still feel it would be great to have a zoom mechanism on your binocular, please stop to consider why three of the most respected manufacturers of binoculars (Zeiss, Leica and Swarovski) don’t have a zoom binocular in their line-up. NOTE: The Leica Duovid only appears to zoom between its two fixed powers. If a high-quality zoom ever comes to the market, Leica is likely to be the company responsible.

*****

Yes, the above has been posted several times. But then, the problem has been raised several times, too.

If you still want a zoom instrument, please go ahead; sadly, experience is a far better teacher than I will ever be.

That monograph addresses several other bino misconceptions and I would be happy to send it to you should you send me your personal email address—my computer is full of them.

Again, welcome to our little family of misfits who might—just after taking the dog out at 3 a.m. in 18 degree weather—have to check the Cloudy Nights account before returning to bed . . . GUILTY!

Cheers.

BillC