Teresa,

Over the years I've had changing preferences for binoculars (since my first pair
in 1953 +-), and I think I've learned a bit about the compromises you endure
when making decisions about power, weight, and cost.

After going through several 7, 8, and 10 power binoculars of low and medium
price, I got a pair of B&L Elite 10x42 binos three years ago. In comparison with
the other 10x binos I had owned and used they were exceptional, and the decision
vs Zeiss and Leitz 10x came down to "personal fit," a most important factor by
the way, rather than optical quality, which was pretty much the same.

I have always been a great proponent of the philosophy that "In the West you
need 10x and in the East you need 7x," based on the relative habitats of the
open spaces and towering conifers in the West, and tight deciduous woods full of
nervous, rapidly moving warblers in the East.

However, as my birding habits increasingly involved carrying a scope (30xWA) and
my 10x binos, I became increasingly discontented with my binos. I came to
realize that I was missing a lot of birds because of the limited width of field
and, to a lesser degree, limited depth of field and unstable image, when I was
dealing with passerines in wooded areas. And I was finding limited benefit of
the 10x power with water birds and sparrows at a distance, because the scope was
so easy to use as an alternative.

Last spring I went on a trip to the east coast for warbler migration. The
preparations for the trip coincided with a particularly bad day with my 10x
binos, missing bird after bird in Theler Wetlands' densely treed areas. So, I
broke down and bought a pair of Zeiss 7x42 BGAT binos.

I am now a convert! First of all, I got 22 lifers in 2.5 hours at Garrett
Mountain in NJ. And I ~know~ I would have missed many of those nervous critters
with 10x binos of any brand.

The 7x42's are so brilliant and crisp compared to the 10x (of any brand), and
the width of field is so great, that I have become convinced that 7x is the best
first power, 8x has the faults of both and none of the advantages, and 10x makes
the second bino choice if you want two pair.

Today, when I go birding, I take my 10x and 7x binos and my scope. Invariably,
when arriving at a site, I grab the 7x and the scope with 30x WA mounted. Even
when the site is a shoreline. I find that the extra power of the 10x very often
does not really provide a better, or more definitive, image, and certainly not
as steady an image -- just as I rarely use the zoom or 60x eyepiece on my Kowa
scope.

To a certain degree, power is illusory. A bigger image is not everything,
particularly where heat and atmosphere are involved, where a steady image is
important, or when you have to get on a moving bird in tight confines, or find
sparrows that jump up and down in the grass.

So, this is not an appeal that you get 7x binos. Rather this is an expression by
one person, with one person's peculiar experiences, of what fits him best after
many years of trying. But it ~is~ an appeal that you consider the many
compromises when choosing a bino - not just the philosophy that more power is
better - even when stabilized. Powerful, perfectly stabilized binos are useless
if you can't get on, and stay on, the bird.

As for BVD, Better View Desired -- as neat as his articles are, and as earnest
his work, I find serious problems with some of his methods.

For just one example, his comparative image resolution test involves using a
pattern printed on the back of a five dollar (I think) bill. The image is a
series of closely spaced vertical lines, and the test involves determining at
what distance you can just discern the separate lines. A nice idea, a convenient
substitute for a typical test chart image. He tells you to measure the critical
distance with your binos, and the distance will tell you their quality.

However.... He uses the image only in a vertical position and, rather than
instruments, he has you use your (and he uses his) eyes. A deadly combination!!
All eyes have some degree of astigmatism, a defect that is demonstrated by
viewing ~closely spaced lines~. And the observation of the defect is dependent
on the axial positioning of the lines. (If you look at your glasses
prescription, if they correct for astigmatism, the prescription includes an axis
measurement in degrees.) If the vertical test image he proposes happens to
coincide exactly with your personal astigmatism, you will get a great image and
a long critical distance - with information that you have great binos. If your
astigmatism is on the opposite axis (by 90o), you will get a terrible image of
the test pattern, a short distance, and the judgement that your binos are
terrible. With an astigmatism axis anywhere in between, you will get a
relatively defective image based on the axis of the target. If you use your
glasses during the test, the results will depend on the degree to which your
glasses prescription properly corrects your astigmatism ~today~, in fact at the
particular ~hour~ today - all of which is another issue.

While his test has validity if one understands these factors, and how to correct
for them, the fact that he doesn't offer that information has me worried about
his relative expertise re: optics. Nowhere in the volumes of stuff on his web
site do we hear about his qualifications or any optical test equipment he uses -
at least at my last viewing a few months ago. (I hope he has changed his
methodology since that last viewing of mine - I passed my concerns to him at
that time.)

As for other issues, the list of criteria you provide makes the perfect example
of "mutually exclusive decision factors" and looming compromises:

Light weight, highest quality and waterprooof. (The waterproof Zeiss weigh 45
ounces vs 28 ounces, but experienced birders have been carrying the
non-waterproof Zeiss into jungles for years. I have never seen a truly
highest-quality bino that is light weight.)

Light gathering ability and light weight. (By natural law, although
over-emphasized at times, more light means bigger objective lenses and
geometrically higher weight. You can't have both brightness and lightness in
equivalent quality and power binos. And attempts to lower weight by reducing
prism size increases light loss. But there are some misunderstood issues re:
exit pupil here, and what one really means by light-gathering can be confusing.
Nikon put out a pair of very expensive roof-prism binos that were just
god-awful, as dark as an ink well. It was a prism design and eyepiece issue --
they had big objectives.)

So, watch out for ~the answer~ re: optics. There is none. There is only the
resolution of a number of compromises with compromises of your own, hopefully
with hands-on personal testing and decision making you have done, rather than
the advice of a salesperson, the declarations of a self-appointed expert, or the
inane ramblings of a 7x-centric birder on Tweeters.<G>

Good luck,

Jerry Blinn


E-mail from: Jerry Blinn, 25-Dec-1996