8x42 VS 7x50 Binoculars | Optics Trade Debates

By Maruša Justinek Oct 14, 2020

Welcome to another Optics Trade debate. Today, we are going to compare the features and the differences of binoculars with 8x42 and 7x50 configurations.

With 8x42, the roof Schmidt-Pechan prism type is most popular. The eyepieces can be set to multiple positions (twist-up eye-cups), the housing is made out of plastic, aluminum, or magnesium – it depends on the price. There is a central focusing mechanism, as a mechanism individual for each eye is rare; almost impossible to find. It features objective lens covers, a diopter on the right eyepiece with a single hinge, or an open bridge design. The open bridge design is usually limited to higher-priced binoculars.

Moving on to the 7x50 category, the shape itself shows how different these binoculars are – because of the Porro prisms, which almost all binoculars with this configuration have. The eyepieces are made out of rubber and are foldable – not a good solution. The focusing is individual for each eye-piece, so you set the focusing for each eye once, and then the eyes do the focusing. What you gain from this is waterproofness. They are usually made out of plastic and aluminum, rarely out of magnesium, and covered with rubber.

What about the prices? With 8x42, the prices differ all the way from 100 € to 3000 €. With 7x50, the prices differ from 100 € to 1200 € – there are only two more expensive models. 8x42 binoculars can be used for almost everything: hiking, birdwatching, traveling, you name it – these are the most all-round use binoculars on the market. 7x50 is usually for only two purposes: either marine use (on sailboats, ships, etc) or low-light use.

Now, for the differences in the optical performance. Naturally, the 7x magnification will, in theory, provide its users with a wider field of view. But, in practice, the 7x50 binoculars usually have 125 m-140 m of the field of view. With the 8x42 models, they have around 135 m all the way up to 150 m of the field of view. In theory, 7x should provide more, but in practice, it is different. The most expensive 7x50 binoculars have 145 m of the field of view. If you look at the same price in the 8x42 category, they all provide around 130 m.

If we take a look at the exit pupil on the 7x50 configuration, it is of a greater diameter. Low light performance is much better on the 7x50. That is due to the bigger exit pupil (5.5 mm and 7 mm) and individual focusing. With central focusing, it is more difficult to focus on the object in low-light. The Porro prisms will also transfer more light through them. – the light transmission rate is higher with Porro prisms than with roof Schmidt-Pechan prisms. So, 7x50 are always brighter and better for low-light use.

What about use with glasses? For use with glasses, the eyepieces that can be set to multiple positions are a better solution than foldable rubber-eye cups. It is difficult to fold them and folding them may cause damage to the rubber. For general comfort (those not wearing glasses), 7x50 is a bit better. Normally, in terms of holding them, 8x42 are better because they are more lightweight – especially the ones with an open bridge.

7x50 binoculars are almost 50% bigger than 8x42 binoculars. In terms of weight, 8x42 models are usually 750 g, and 7x50 models always weigh more than 1 kg – 40 % heavier. In terms of pricing, 7x50 are usually cheaper than 8x42, the reason for it also being that it is cheaper to produce Porro prisms. So, if you want your pair of binoculars to be universal and use them almost everywhere – hiking, hunting, etc. then 8x42 is better. 7x50 is aimed at specific users: marine use and low-light hunting.