Vortex Viper HD 10x42 vs Razor HD 10x42

Field of view: Razor HD leads

Razor HD 10x42 prints a field of 362 ft at 1,000 yd, or 6.9 degrees. Viper HD 10x42 prints 341 ft, or 6.5 degrees.

Among the 87 models of this size, 12th place on field of view goes to the Razor and 29th to the Viper. The median for the size is 336 ft, so both sit above it.

Brightness at dusk: equal

Both models work out to a 4.2 mm exit pupil, a twilight factor of 20.5 and a relative brightness of 17.6. These figures are calculated from the 10x42 size, so they match.

Nikon defines exit pupil as the effective objective diameter divided by magnification, and says a larger one gives a brighter view in dim light. With the same figure on both, the numbers give neither model an edge at dusk.

Eye relief: Viper HD leads

Eye relief is 17 mm on the Viper and 16.5 mm on the Razor. The median for 10x42 models is 16 mm, so both clear it.

The RSPB shop says eyeglass wearers should look for at least 16 mm. Both models meet that figure, and the Viper offers a little more.

Weight and close focus: near tie

Weight is 24.8 oz for the Razor and 24.9 oz for the Viper. The size median is 24.9 oz, so the Viper sits on it and the Razor a hair under.

Close focus is 6 ft on both, shorter than the 7.5 ft median for the size. Either one lets you look at subjects closer than most 10x42 models do.

Build and fit: close match

Both are filled with argon and printed as designed to withstand harsh weather. Both focus from the center wheel and adapt to a tripod. Each names hunting as a use.

Eye spacing runs 55 to 74 on the Viper and 55 to 75 on the Razor. Razor prints a roof prism, and Nikon says roof prisms can lose resolution without a phase-correction coating.

Price band

Vortex lists the Viper in the $500 to $1,000 band and the Razor in the $1,000 to $2,000 band. The wider view and the longer eye relief sit on opposite sides of that gap.

See binoculars in the $500 to $1,000 band or binoculars above $1,000 for other models near each price.

Viper HD 10x42 or Razor HD 10x42

Both share a 4.2 mm exit pupil and a 6 ft close focus, and their weights are 24.8 oz and 24.9 oz. Razor HD wins on view width, 362 ft against 341 ft. Viper HD wins on eye relief, 17 mm against 16.5 mm, and sits in the lower price band.