Nikon PROSTAFF P7 10x42

Is the Nikon PROSTAFF P7 10x42 worth buying?

Yes, the Nikon PROSTAFF P7 10x42 is worth buying at £189 if you watch birds in British weather and you wear spectacles, and it is the wrong pair if you want the most zoom for the least money. It is a 10x42 roof prism binocular in a magnesium body, and 540 owners rate it 4.6.

Three figures settle it before you spend anything. The 42 mm objective at 10x leaves a 4.2 mm shaft of light for your eye, 15 mm of eye relief lets a spectacle wearer keep the whole picture, and the body keeps water out at 1 m for up to 10 minutes. Add an oil and water repellent coating on the front and eyepiece lenses, and you have a pair built for a wet Saturday rather than a sunny afternoon.

What does the 4.2 mm exit pupil of the Nikon PROSTAFF P7 10x42 mean?

The exit pupil is the shaft of light that leaves the eyepiece, and on this pair it comes from 42 mm divided by 10x, so 4.2 mm. Your own pupil opens to roughly 2 mm to 3 mm in daylight and 5 mm to 7 mm at dusk, which means a 4.2 mm pair stays bright right through the hours when birds are most active.

In area terms, 4.2 mm works out to about 17.6 square millimetres of light, against roughly 12.3 square millimetres on a 12x42 pair, so close to 45 per cent more. The 62.9 degree apparent field keeps the picture open rather than tunnel-like, and 122 m of view at 1,000 m is wide enough to follow a bird in flight without losing it.

What comes in the box with the Nikon PROSTAFF P7 10x42?

A neck strap, a case, an eyepiece cap and two objective lens caps come in the box. The body measures 15 cm long by 13 cm wide and weighs 600 g, so it is a full-size pair that hangs on your neck for a whole morning rather than something you forget in a coat pocket.

Set-up takes a minute. The right eyepiece carries +/-4 dioptres of adjustment, so you tune it once to your own eye and keep your glasses on for every session after that. A tripod socket sits on the underside for the days you want to watch one nest for an hour without your arms complaining.

Where does the Nikon PROSTAFF P7 10x42 fall short?

At 10x this pair will not fill the eyepiece the way a 12x does, so a small wader at 150 m stays small and an identification can take longer. If reach matters more to you than brightness, the magnification is the wrong way round on this one.

The eye relief stops at 15 mm, which clears most spectacles but can leave thick frames sitting a little far from the glass. At 600 g and £189 it also asks for a real commitment, and with 540 ratings the record behind it is much shorter than the budget pairs carry, so you are buying on a smaller sample than you would with a £25 pair.

How does the Nikon PROSTAFF P7 10x42 compare with the Gosky 10x42 and the Celestron Outland X?

The Gosky 10x42 Roof Prism at £72.99 gives the same 10x magnification and the same 4.2 mm exit pupil for £116 less, and it throws in a phone adapter and a tripod. What the extra £116 buys on the Nikon PROSTAFF P7 10x42 is a magnesium body, waterproofing to 1 m for 10 minutes and 540 owner ratings against 130. Birdwatch in the rain and the Nikon is the safer buy; watch in fair weather and the Gosky leaves the money in your pocket.

The Celestron Outland X 8x42 at £85 takes the other road: 8x magnification gives a 5.25 mm exit pupil, so it holds its brightness longer than the Nikon as the light drains away, and it comes with a limited lifetime warranty. It cannot match 10x for reach, so a distant bird stays harder to name. Take the Celestron for dusk and long cover, the Nikon for 10x detail in a body that shrugs off a downpour.