One of the first steps in narrowing down which binoculars will suit your style of birding best is to explore the different size options. Both 10×42 and 10×50 are solid choices for bird watching. In this article, we will explore the advantages and disadvantages for both 10×42 and 10×50, and compare how these pros and cons affect their practical usage for bird watching.
The 10x indicates that they share the same power of magnification. The main difference is in the size of their objective lenses – the light-gathering part of the binoculars. This difference has a bearing on some of the best uses for each configuration of binoculars.
10×42 is most suited to normal to good light conditions, especially in open spaces with good visibility. If the size and weight are strong factors, then this size is more portable than the 10×50. The price is normally lower too.
To go directly to see which features are common across some 10×42 binoculars in our comparison post here.
10×50 performs better than the 10×42 at night and in low light. The larger objective lenses gather more light in these conditions. In general, the 10×50 outweighs the 10×42, with larger dimensions and a bigger price tag.
To head straightaway to compare the features you get for your money across a range of 10×50 models, feel free to check this round-up.
If you are confused about whether to buy 10×42 binoculars or to give 10×50 a try, then you are in the right place. We aim to point out the main considerations so that you can make an informed choice about whether to go for one of these binoculars.
What is the difference between 10×42 and 10×50 binoculars?
10×42 vs 10×50: physical difference
The second number in the size of the binoculars refers to the diameter in millimeters of the objective lens (the pair of lenses furthest from your eyes).
So the binoculars with the 50mm objective lenses will be slightly larger than the binoculars with the 42mm objective lenses.
This in turn means that the whole body of the 10×50 binoculars is a little larger. The barrels are wider because the diameter of the lens is wider.
To stay in proportion, the length of 10×50 binoculars tends to be larger as well. This means that the 10×50 is bigger than the 10×42, not only in dimensions but also in weight.
Usually this increase in weight is negligible, though. For those people whose birding takes place close to home, or from a stationary position like in a backyard or bird hide, it’s probably not worth giving too much consideration to the extra weight.
It could have a bearing, however if you tend to do a lot of walking over challenging ground on your bird-watching excursions, or if you take the binoculars with you when you go hiking. In this case a lighter pair may make a noticeable difference.
10×42 vs 10×50: optical difference
In bright conditions, where the pupil of your eye constricts, there will be little perceivable difference between the two pairs. Both sets of lenses will be able to gather plenty of light.
Where their differences will show most, though, is in low light conditions. This is caused by the variation in the size of the exit pupil.
In a dim environment, such as the time around sunrise or at twilight, the pupils in our eyes expand in order to allow in more light.
10×42 vs 10×50: exit pupil
To calculate exit pupil, divide the diameter of the objective lens by the power/magnification. (Most manufacturers list exit pupil in the spec to save you doing the calculation yourself.)
For a 10×50 binocular, divide 50 by 10. Exit pupil = 5mm.
For a 10×42 binocular, divide 42 by 10. Exit pupil = 4.2mm.
Because the exit pupil on a pair of 10×50 is larger than that created on a 10×42, it means that the 10×50 will yield a brighter image. Larger waves of light are able to enter the objective lens and reach your eye.
In this instance, a 10×50 has the advantage over a 10x. Not only is it slightly brighter, but it is also easier to use with less chance of black rings around the edges hampering your view. Beginner birders will find this especially helpful.
For more in-depth exploration of how exit pupil is important for bird watching using optics, we have an article here explaining its practical application: What does exit pupil mean in binoculars?
10×42 vs 10×50: price difference
Broadly speaking, the 10×42 models cost less than the 10x models in the same range.
In the 10×50 pair, there is a slight increase in the size of the glass, to increase the magnification, and thus also the physical size of the body of the binocular. Though 10×42 binoculars have a different power to 8×42 binoculars, the same sized body is often used for both models by manufacturers.
This means that this size of chassis is more popular. Therefore it can be sold more cheaply because it is produced on a larger scale than the less common 10×50.
So with this in mind, it should be possible to purchase 10×42 binoculars of a higher quality than you could find for the 10×50 configuration. This could, in theory, make the 10×42 better value.
Are 10×50 binoculars good for birding?
Because of their larger physical size and weight, 10×50 binoculars are good for more stationary birding. For instance, you might prefer 10×50 binoculars when you have less need to move around and carry them from place to place.
The 10×50 binoculars perform especially well in low light conditions, like dawn or dusk or when it’s cloudy. They are good for bird watchers who use their binoculars at night.
If there is not a lot of light in the environment, bird watchers need binoculars that can gather light most effectively. With their 50mm diameter objective lenses, the 10×50 binoculars let in lots of light.
If a lot of your birding is done at either end of the day, when light is at its lowest, or in forests, woods or jungles, which tend to be darker environments, then 10×50 binoculars will work well.
10×42 vs 10×50 binoculars: which is best for birding?
The main similarity between the 10×42 and 10×50 binoculars is their power of magnification. Also, most 10×42 and 10×50 binoculars are of the roof prism configuration, with a central focussing mechanism.
They do have some crucial differences, though. These differences create advantages and disadvantages for each sized model.
In normal to good light conditions, 10×42 is the best choice. If you are out during the day when the sun is higher and there is more light, or in open spaces with good visibility, then 10×42 binoculars will suit your needs.
In additional, the 10×42 is more compact and lighter. The price is lower than the 10×50. To compare prices using some examples of 10×42 binoculars, check here >>> Top five 10×42 binoculars for bird watching
At night and in low light, a 10×50 will be better. Brightness seen through 10x50s is similar to an 8×42 but with more detail provided by the boost in magnification. The 10×50 also costs more and is bigger in weight and dimension.
For a comparison of specific features available right now, feel free to take a look at these top 10×50 binoculars.
We would always recommend that it is best to choose according to your own individual requirements and buy the best possible pair for your budget.