What binocular power?

To: Birding-Aus <>
Subject: What binocular power?
From: "David Adams" <>
Date: Wed, 28 Mar 2007 07:36:48 +1000
I've always used 8x binoculars but, as far as I can tell,
magnification is not the single most important factor. Generally,
you're going to get a smaller angle of view with higher power
binoculars. It's easy to give too much weight to magnification when
buying optics. Keep in mind that higher magnifications don't deliver
as much benefit as you might think. As an example, imagine you're out
looking at a Lesser Spotted Dingle-Dangle (or is it a Greater
Spotted?) standing on a post 100m away. With the naked eye it looks
100m away, assuming you've got standard vision. Now imagine you're
using a 2x binocular (if such a thing exists). The bird now appears to
be 50m away. You've just moved 50m closer. Now imagine you've got a 4x
binocular. The bird now appears to be 25m away. You've doubled the
power but only halved the gain. At 10x, the bird seems to be 10m away.
So, the 2x gains you 50m total and the 10x gains you only and addition
40m for 90m total. (My explanation here is off the top of the head and
I've long found the subject a bit confusing. If someone who is smart
about optics wants to post a correction or better explanation, I'd be

A couple of factors that may be more important to your satisfaction
than magnification:

* Quality of optics
A high-quality 7x binocular will help you see and identify a lot more
birds than a lower-quality 8x or 10x binocular.

* Weight and comfort
Binoculars don't do you any good unless you have them with you and, in
a lot of cases, already around your neck. A $1,000 pair of binoculars
aren't help much if they're in a drawer. I'm using an old pair of
Pentax 8x42 binoculars and, when I bought them, was very tempted by
the 7x pair. The 7x were much lighter, smaller, very nice in the hand,
bright, and provided most of the magnification of an 8x. I got the 8x
as they're within the size I'm willing to carry around with me all of
fthe time.

* Close focus
Some binoculars can focus on objects 2m away, others need 4m. This
doesn't matter all of the time but having binoculars with a short
close focus ability turns out to to helpful surprisingly often.

* Waterproofing
If you don't mind getting wet, consider putting this feature on your
list. It's reassuring to have binoculars that are designed to survive
a soaking. (Although, as people have already reported, this isn't a
feature that is guaranteed for life.)

With all that said, if you get 8x binoculars you don't have to worry
about the other kids laughing at you ;-) Just get the highest quality
set you can reasonably afford and enjoy!

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