Low light bins

To: "Michael Hunter" <>, <>
Subject: Low light bins
From: "Rosemary Royle" <>
Date: Tue, 8 Mar 2011 12:06:48 -0000
I am always interested in communications on this list regarding binocular 
magnifications. In the UK the most popular magnification is 8x40 or 8x42 and 
10x are not much used. I realise that birding in Aus is a bit different to 
birding in the UK but any delusions I had about you all being so fit and macho 
that you could carry heavy 10x bins with ease has just been dispelled by the 
recent "harness" thread!

Often 10x binoculars are so heavy that they are hard to hold steady enough to 
get any advantage from the extra magnification.  A harness can help with 
carrying but when actually using them you really need a tripod or a Finnstick. 
(I have only ever seen the latter in Finland - it is a T shaped piece of wood 
which you hold at waist height and use to support the binoculars at eye height 
- it really works!) The only time I could see that 10x might be really useful 
is if you are, say, sea-watching, and do not have a scope. In these kind of 
conditions, putting heavy bins on a tripod can be quite a revelation - the 
world suddenly gets much sharper! Photographers use a tripod for good reason. 

(Our first pair of "real" birdwatching binoculars were Swift Audubon 8x42 which 
were huge and heavy - a tripod or more usually, a handy fencepost or rock, made 
a lot of difference to the sharpness of the image)

For gloomy forest conditions then it is the objective size rather then 
magnification which is important, and also particularly the depth of field, 
plus close focussing and number of turns to focus. 

However, the objective size of course also increases the weight, but it is 
worth noting that due to improvements in technology the light gathering power 
of bins has improved a lot over the last 20 years and it may no longer be 
necessary to use x50 in low light. A modern 10x40 will be as bright as an older 

And unfortunately, the more you pay, the better the bins are in low light - 
though the marginal benefit soon starts to get very costly!

And as a footnote, Nikons are often reckoned to be very "bright" - i.e. gather 
a lot of light. 

The article referenced by Dave Torr is really very interesting and covers 
material I have never seen before - however, it neglects to mentions depth of 
field as an important characteristic. This is possibly because it is rarely 
mentioned by manufacturers, so it is hard to find out how good a particular 
model is, however good reviews will cover it. 

Peter and Rosemary Royle
Wales, UK

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the birding-aus mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU