10x42 roof prism binoculars, green

When 10x is the better choice

Ten times magnification makes most sense where birds are far away and the light is good: on an estuary at low tide, at a reservoir, on moorland or along a coastal path. A curlew 200 metres away looks as if it were 20 metres away, close enough to see the curve of the bill.

The price of extra magnification is a narrower view and more visible hand shake. The supplier lists a field of view of 102 m at 1,000 m, which is about 5.8 degrees. Bracing your elbows against your chest, or leaning on a gate or a wall, steadies the view noticeably. If you mostly watch gardens and woodland, the 8x42 version is the easier choice.

What we can tell you about this model

The 42 mm objective lenses give an exit pupil of 4.2 mm, a little smaller than an 8x42 but still larger than your own pupil in daylight. The roof prism design keeps the barrels straight and the body slim. You focus both sides at once with the large central wheel.

The supplier sells the series as waterproof but gives no IP rating and does not state the prism glass or the lens coatings, so we do not claim them. For regular use in heavy rain, look at our IPX7 rated 12x50. Our guide Looking after binoculars in wet weather explains how to dry any pair after a wet day.

Field of view in practice

A field of 102 m at 1,000 m means that at 100 metres you see a strip about 10 metres wide. That is enough to keep a flock of lapwings or a family of swans in view, but it takes a little practice to find a single small bird in a tree. Look at the bird first, then raise the binoculars without moving your eyes. What the numbers on binoculars mean explains how to convert the different field of view figures.