ZEISS 7x42 CLASSIC BINOCULAR

 Al Miller

When the Zeiss 7x42 was first pulled out of its box, the usual routine began. First, to adjust the binocular for my eyes, the left lens was focused on a street sign 106 (measured) yards away. Then the diopter adjustment on the right eyepiece was rotated until the same sign was clear and distinct for the right eye. That chore completed, the glasses were next aligned on a series of targets, the distances to which had been electronically measured.

First up were some black numbers, 6 inches high, (personally measured) on a white door 437 yards off. At that distance, threes and fives resemble one another to a remarkable degree if a binocular’s resolving power isn’t quite what it should be. Through those bright Zeiss lenses, there was no doubt as to which was which; distinguishing threes from fives took no more than a quick glance.

Next, a wire mesh fence on a hill 454 yards distant stood out clearly against a backdrop of trees and brush. The narrow, horizontal air vents on a rooftop air conditioner 325 yards away were so well defined, I could have counted them with ease.

It suddenly occurred to me that I hadn’t touched the binocular’s focusing wheel, not once, since it was originally zeroed for my eyes. There had been no need. After checking a number of other, widely spaced visual targets, it was obvious that everything between 53 and 456 yards was in focus. Actually, the hills beyond the 456-yard target still seemed clearly delineated to my eyes, but the electronic rangefinder I used is limited to 600 yards so there was no means of checking on anything farther out.

Nobody lists depth of field on an optical product’s spec sheet. It’s not that the subject is irrelevant or unimportant, but to date, optical engineers haven’t been able to agree on a standard that will serve as a basis for comparison between one binocular’s depth of field with another’s. They’re working on the problem though.

How important is depth of field? Well, if it’s fairly shallow, a viewer will find it necessary to refocus the glasses almost every time his eyes shift from one object to another out there at 200 or 300 yards. That’s distracting. It can be frustrating too.

If a viewer spots, say, a hint of movement and has to focus his glasses before he can identify its cause, he may miss the opportunity entirely. Whatever generated it may be hidden or gone by the time the glasses’ image is finally clear.

With an almost infinite depth of field, like that of the 7x42’s, all a spotter need do is clap the binocular to his eyes and point at the source of disturbance. No time lost refocusing.

Next up was the Edmunt Resolving Power chart. Featuring the USAF’s 1951 test patterns, it is one of the industry’s standards.

There are 25 test patterns on the chart, each of which is 2 inches square. Each square contains a series of three-bar patterns, each smaller than the ones next to it - much like those that appeared on page 70 of Rifle 175 (January 1998). The AF patterns are printed in black, red, yellow and blue. In addition, they are oriented at different angles to help identify the effects of any monochromatic or chromatic aberrations of an optical instrument’s lenses.

According to the Zeiss spec sheet, the 7x42’s close-focus distance was 11.5 feet. To check that, the Edmund chart was mounted on a solid base and the binocular worked in until it was impossible to focus them. Then they were backed away, little by little, until the focusing wheel brought the design in sharp and clear. Marking the spot, a tape measure was employed from the chart to where the glasses had been. Result? Just as specified - 11.5 feet.

Next, the glasses were moved back until 20 yards separated them from the chart. Benched, to keep them rock-steady, each pattern was examined through the glasses to find the smallest bar series that was distinctly outlined - no fuzziness whatever - with sharp corners and edges plainly visible. It happened to be the fourth group in the -1 column.

Next, the same approach was taken with some borrowed 8x and 9x binoculars. Both were high-grade glasses and fairly expensive. When they were focused on the same fourth group in the -1 column, the tiny black bars were a patternless blur.

Finally, I turned to a big 10x50, also first-class quality. Its image showed the fourth group in the -1 column clearly, but the smaller fifth group, right below it, was fuzzy. The fourth-group bars in the 10-power’s image were slightly larger than they had appeared through the 7x42s, but they were no clearer. In short, it took a darned good 10x binocular to show the same detail the lighter, more compact 7x42s had.

All those tests were conducted under an overcast sky, a rarity around here, but the timing was just right for my purposes. When checking out binoculars, it’s poor-light performance that separates the useful from the so-so models.

The better part of a day was spent down on the Sonoran desert. Again, it was partly cloudy, which gave an opportunity to see how the Zeiss 7s performed when peering into shadows, beneath rocky overhangs and through cactus screens. Those big objective lenses took advantage of all available light, even when there wasn’t an abundance to begin with.

The extra-wide field of view came in handy too. It enabled me to plunk my butt down as comfortably as possible, then peer through the glasses. My eyes could wander around the entire image, examining anything that looked interesting. Since the image covered so much real estate out there, shifting the glasses was seldom necessary. My position didn’t require changing very often either. A wide field of view might not be much of an advantage in the woods, but in open country it’s worth more than it costs.

Refocusing was only necessary a couple of times: an unfamiliar songbird perched on a bush about 20 yards away, and a small falcon was using a tall saguaro as an observation tower. He couldn’t have   been more than 30 to 35 yards distant. Those close-focusing incidents aside, the focusing wheel was ignored the rest of the day.

Since the magnification level is so low - 7x is considered low by most outdoor types these days - there was seldom any need to find a rest to brace myself in order to use it. Held offhand, it didn’t bounce or jump around like more powerful glasses often seem to.

About the only gripe I have concerns that little nylon neck strap. Only .4 inch wide, it began to make its presence felt after a couple hours tramping around. Seems to me Zeiss could offer a more comfortable strap to complement such a fine fieldglass. A rain guard and a zippered leather case are supplied with each 7x42.