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 binoculars resolving
power isnt 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
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
hadnt touched the binoculars 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 products spec sheet. Its not that the subject is irrelevant or
unimportant, but to date, optical engineers havent been able to agree on a standard
that will serve as a basis for comparison between one binoculars depth of field with
anothers. Theyre working on the problem though.
How important is depth of field?
Well, if its 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.
Thats 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 7x42s, 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 USAFs 1951 test patterns, it is one of the industrys
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 instruments lenses.
According to the Zeiss spec sheet,
the 7x42s 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-powers
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, its 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 wasnt 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 didnt require changing very often either.
A wide field of view might not be much of an advantage in the woods, but in open country
its 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 couldnt 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 didnt 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.
To sum up: the Zeiss 7x42 is the finest
binocular I have ever tested, bar none. It shows all the detail expected from a quality
10x glass; the relatively low magnification allows it to be used for long periods of time
with no threat of eye strain. Admittedly, the binocular isnt cheap, but my
impression is there are several lifetimes worth of use built into it.