What binocular power?

To: "Birding-aus \(E-mail\)" <>
Subject: What binocular power?
From: "Peter Shute" <>
Date: Mon, 2 Apr 2007 13:23:07 +1000
 wrote on Tuesday, 27 March 2007 3:30

> I have read many articles about choosing binoculars, and most
> seem to suggest that 8x40 is the best compromise between
> magnification, field of view and weight for birders.  One
> article even suggested 7x or even 6x in order to get a better
> field of view.  But I've been surprised how many birders seem
> to use 10x.  What do people recommend?

OK, this is what I've ended up with: Bushnell 8x42 Legend (Porro) -
$269. These fulfil the basic requirement of being vastly better than my
no-name 8x21's.  They claim to be water and fog proof, although I see no
mention of them being nitrogen purged so we'll see how they go in that
respect.  They claim they can be submerged under water.

They have a wider FOV - 143m vs 126m - and have the relief (15mm) to let
me see it all (I could only see about 105 before).

The image doesn't get foggy if strong light falls on the objective.
Close focus is acceptable at 3.6m, the same as my old ones.  The eye
cups twist up, so I can expect to find them set roughly as I left them.
Even with only 15mm relief they can still black out when the cups are
right in - my eyes musn't be very deep set or something - so that's
going to be a handy feature.

Depth of field is ok.  Difficult to measure, but no worse than before.

I did a few hours internet research, trying to narrow down the models I
would look at. Some good ones are simply not available in this country
(Nikon Monarch 8x36).  Others would require quite a bit of travel to see
them.  I was going to spend up to $700, and had decided I was prepared
to buy 8x30's to get the FOV if necessary. I spent a whole morning
looking at Legend 8x32, 8x42 roof prisms, and a few much more expensive
ones for comparison, but couldn't convince myself. I finally looked at
the porros and it was so much better, and so much cheaper, that it was a
fairly easy decision.  I was keen on the 1.2m close focus of the 8x32
roofs, although I don't know why, so I've sacrificed close focus for a
slightly wider view and a much better image.

The difference in image quality was detemined by the ease with which I
could read some fine print on a shop poster, and that difference was
quite pronounced.  Brightness, etc is harder to measure, but the porros
seemed similar to the roofs in that regard.

I'm a bit disappointed, but relieved, that I couldn't find anything
closer to my budget, but what I was looking at just wasn't worth the
extra money.  The solution would probably be to get myself to one of the
birding shops where they have a better range, but I can't see myself
finding the time for quite a while.  At this price I won't be
disappointed if I feel the need for better ones, or if they end up
getting misaligned.

Interestingly, in my research I came across several comments from people
who ended up buying these porros instead of the roofs.

As for the advice to test them on distant flying birds - I tried, but in
Melbourne CBD this is a bit of a tall order and involves quite a bit of

Peter Shute

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