When is 8 more than 10?
A new birder writes to us:
I want as much magnification as I can get from my binoculars. Is there any reason (besides the price) to get an 8-power binocular when I could have 10 power or 12 power? Don't I want to see the absolute most possible?
The Power of Magnification
Actually, with a higher power binocular you may end up seeing less!
One would think that the more magnification, the more you could see. But it's not necessarily so. Binoculars let you see more only if the image is steady. And the higher the magnification, the less steady the image looks. This is because as the magnification increases, the shake increases as the same rate. At some point, the wobble negates the increased resolution that more magnification provides.
Steady does it
Everybody's hands tremble to some degree, but some have steadier hands than others. And even a birder with normally steady hands won't be able to hold a binocular as still after running up a steep hill to see a bird as the same person sitting quietly.
If your hands are quite steady, you can probabaly hand hold 10-power binoculars without suffering too much from the tiny tremble your hands impart. Some people even use 12-power binoculars, though many find that this high magnification requires some sort of stabilization — tripod, monopod, deck railing, or something like that. Most birders use 8x or 10x binoculars, which they can carry with them and not need any other equipment to steady their binoculars.
Swarovski makes a high-end 12x42 binocular, the NL Pure 12x42. It's often purchased with the optional Forehead Rest, which gives the birder a third point of support to steady the image. Birders have reported to us that they find they can comfortably hand hold their 12x NL Pure by using this special gadget. But that is the exception.
It's generally felt that 10 power is the upper limit of hand-holdable binoculars. This is particularly true when a birder's muscles are fatigued. While watching warblers in the treetops, for example, the longer a birder's arms are raised, the harder it gets to hold the binocular steady. That's why few binoculars with over ten power are marketed to birders.
Many experts believe that birders can see just as much or even more with 8 power binocular. It is possible to find even lower-power binoculars, which are helpful if a person has a noticeable tremor Hower we find that that few manufacturers make binoculars with less than 8-power magnification any more. Most birders can hand hold at least 8 power.
Field of view
Another advantage of lower power binoculars is field of view. If you look at two binoculars that are the same line and the same manufacturer, the 8x42 will have a wider field of view than the 10x42.
In the two photos, the first one is taken at 10-power and the second one at 8 power. You can see that the berries are bigger in the 10-power image, but the cardinal is not in view. In the lower-magnification image, it's easier to spot the bird because more of the environment is in the field of view. This makes it easier to locate a bird.
As birders get more practice using binoculars, they find it easier to aim at the bird and find it. For this reason, 8x binoculars are the default choice for a new birder. But if you've been using 10-power binoculars and find it easy to spot the bird, and the image is nice and steady, then there's no reason you should deny yourself a new 10-power binocular.
The bottom line is that a binocular with higher magnification might not let you identify more birds. What you need may not be stronger binoculars, but the right ones for your eyes and hands and brain and experience.