Best Bird Watching Binoculars

 Choosing the Best Bird Watching Binoculars

The best bird watching binoculars for one person are not necessarily best for someone else; it depends largely on whether you plan to watch birds in wooded areas or wide open plains, from a distance or as close as you can get. 

I’ll quickly recap on my previous article which can be found at Ezine Articles and which explained what the numbers 8 x 40 mean (for example).  The first number is the magnification.  In other words 8 x binoculars will make your object seem 8 times nearer than they really are and the second number, in this case 40 means that your objective lens is 40mm in diameter.  This signifies the amount of light that you will get but the wider the lens the heavier the binoculars so a compromise is needed here. 

Most birders think that the best bird watching binoculars are 8 x 40 or 8 x 42.

That done, I’ll continue with the other aspects of binoculars for bird watching/

Exit Pupil

This sounds complicated but once again it’s just a measurement, in this case the diameter of light in millimetres which you can see through the eyepiece.  It is measured by a simple sum; you just divide the diameter of the objective lens by the magnification so our 8 x 40 binoculars will have an exit pupil of 5mm.  The larger the exit pupil, the better you’ll be able to see when the natural light isn’t good; for example if you’re watching owls at dawn.

The human pupil has a diameter of between 4 to 7mm so the nearer the size of the exit pupil to our own pupils the more difficult it is to determine objects.  For example, the smaller, more portable binoculars may have an exit pupil of 2.6 but in bright light, our own pupils will contract to much the same size and will be need to be exactly centred over the exit pupil to spot the bird we’re following.

So, for mainly birding in normal daylight 4mm exit pupil will be fine but for bird watching in dim light 5mm will be better.

Prism Design

I won’t go too much into the technicalities, suffice to say that you either have a roof prism or a porro prism and the former are more expensive.  Here is a comparison table to help you decide which you want.

Roof PrismPorro Prism
AppearanceSlimlineWide and quite bulky
Field of ViewWiderNarrower
Depth PerceptionDecreased depth perception caused by straight inline barrels.Offset lenses are wider giving better depth perception.
FocusInternal. Better seals and hence waterproof.External. Seals can deteriorate allowing dampness and dirt to get inside.
BrightnessInferior, but lens can be coated to improve. This is costly.Superior
Robustness of DesignStrongerWeaker
PriceApprox $450 and upwardsApprox $250

Hopefully all this information will help you to choose the best bird watching binoculars for you.  Here are a selection of low to medium priced binoculars.


You can leave comments on this post but not trackbacks. Follow recent comments using this Comments Feed.