Also see Alan Dyer’s comparison of 10×42 roof prism binoculars
A pair of 8×42 binoculars can serve all purposes including astronomy. I test a group of four low- to mid-priced models, all with popular roof prism optics.
Binoculars with 50mm lenses, and either 7x or 10x power, are the models most often recommended for astronomy. However, for stargazing I’ve long been a fan of smaller 42mm binoculars. A good-quality 42mm, as all are here, can show everything a 50mm can, albeit with a slight loss of about a third of a magnitude in image brightness.
However, the benefit of a 42mm is its lighter weight, typically about 100 to 150 grams less than a 50mm, and its more compact size, making it well-suited to other uses such as birding, hiking and spectator sports. The benefit of an 8×42 over a 10×42 is the wider actual field of view, typically about 7.5° to 8° compared to 6° to 6.5° for a 10x model. The lower power also makes it easier to hold steady for sharp views.
Since an 8×42 is a good all-purpose size, almost all now use roof prisms for their compactness compared to bulky Porro prism models. In this survey I looked at a selection of roof prism models from $200 to $500, putting them in a low- to mid-range price class. I present them in order of increasing suggested U.S. retail price, though they might sell for less at some outlets.
For a survey of a selection of lower-power 8×42 models, see my review here.
Celestron Nature DX ED 8×42
Pros: Very good optics with ED glass.
Cons: Focus knob hard to operate in cold weather.
While Celestron has non-ED Nature DX models, for not much more money, the DX ED series features an Extra-low Dispersion (ED) lens for reducing false color fringing around bright targets. That’s a plus point, though at 8x it was frankly tough to see much difference in color between the Nature ED and the comparably-priced non-ED Vortex Crossfire. Both were excellent and very sharp.
In the Nature DX ED, stars were soft in the outer 30 percent of the field but, like the Crossfire, were still well contained at the edge, with no severe off-axis aberration. The field stop in the Nature ED is well-defined and sharp, though it does show some edge darkening. While the focus knob is wide, I found its surface too smooth for easy gripping in cold weather with gloves, especially as the focuser’s grease stiffens in the cold. While the twist-up eyecups have click stops they collapse easily under slight pressure. It is the lightest binocular of the group.
Bottom Line: A great value in an economy roof prism binocular.
Vortex Crossfire HD 8×42
Pros: Sharp images and excellent handling.
Cons: Some false color; edge of field vignetted.
A brand not well known to astronomers, Wisconsin-based Vortex Optics offers a wide range of binoculars. Crossfire is their entry-level series. While labeled “HD,” the optics do not use ED glass, so the Crossfire does show a little false color fringing, but at 8x you really have to look for it on bright stars and the edge of the Moon. The 61° apparent field is ever so slightly wider than the 60° Celestron Nature EDs, with stars in the Crossfire soft in the outer 30 percent of the field.
Even by day, the Crossfire shows darkening of the edge of field with the field stop soft. However, construction is excellent with good ergonomics and handling, though the Crossfire is longer than the other 8x42s by about 1/2 inch (12mm). The focus knob is large, ribbed and easy to operate with gloves on, with better ease of movement in the cold than the Nature ED. The twist-up eyecups have no click stops, but stay extended even under pressure. The Crossfire comes with an excellent padded case, with Vortex’s unique GlassPak chest harness liked by hunters and hikers.
Bottom Line: A fine economy roof-prism 8×42 for all purposes.
Zeiss Terra ED 8×42
Pros: Solid construction and bright images sharp almost to the edge.
Cons: Some false color fringing on bright objects.
Zeiss is a name you do know, but that few can afford. However, their entry-level Terra series is made in China, not Germany. True to Zeiss, the Terra looks and feels high class, but without the Zeiss price. The Terra 8×42 has the longest eye relief of the group, at 20mm. At 60°, the apparent field is not as wide as the Hawke, but is sharp almost to the edge, softening only slightly in the outer 20 percent.
The main drawback I saw was the slight chromatic aberration, adding false color fringing on bright objects. It’s not obvious, but with ED glass at this price point it shouldn’t be there at all. Images are very sharp and snap into focus; there’s no softness or spikiness to the stars, nor any question if you are at the best focus. The field is bright and contrasty, with no ghost images or internal reflections when looking at the Moon. The twist-up eyecups have click stops that are a little mushy but are firm; the eyecups stay put even under pressure. It and the Hawke are the heaviest of the group. The Zeiss lacks the usual threaded hole for attaching a tripod mounting bracket, but for a 8x glass that’s not a detriment.
Bottom Line: Superb construction and sharp images with the Zeiss name.
Hawke Frontier ED X 8×42
Pros: Widest field of view with excellent sharpness across the field.
Cons: The most expensive of the set (though the “street price” is ~ $400).
Hawke Sport Optics is a U.K.-based company, but with U.S. offices in Indiana. Astronomers might not encounter the Hawke brand but should, as their Frontier ED X is a top-class glass. The series has phase-corrected and dielectric coatings on the prisms for bright, high contrast images. In the 8×42, stars are sharp across all but the outer 20 percent of the 65° apparent field, the widest of the 8×42 group tested. The field stop is sharp and well defined, with minimal darkening at the edge.
Overall, I found the Hawke gave the most dramatic views, though the Zeiss was pretty nice. The Hawke’s focus knob is ribbed for good gripping, and remains easy to turn in cold weather. Eye relief is a comfortable 17mm, good for eyeglass wearers. The twist-up eyecups snap into precise position and are removable for cleaning, a feature missing in the other models. Both the Zeiss and Hawke come in similar zipped hard cases, each with a flap with a magnetic fastener, good for quick access for daytime use on hikes. However, the Hawke’s case is bigger than it needs to be for the compact 8×42.
Bottom Line: A great choice for someone looking for high-class performance.
TABLE: 8×42 Roof Prism Binoculars
Weights are measured with captive front lens caps attached as you would likely use them, so will differ from published specs. Eye relief is measured from the top of the retracted eyecup, not from the recessed lens. Actual fields of view were measured by looking at starfields; the apparent field figure assumes 8x power.
|Model||Celestron Nature DX ED||Vortex Crossfire HD||Zeiss Terra ED||Hawke Frontier ED X|
|Weight (g / oz)
|685 / 24.1||712 / 25.1||752 / 26.5||746 / 26.3|
|Actual Field of View (°)
|Apparent Field of View (°)||60°||61°||60°||65°|
|Eye Relief (mm)
|Interpupillary Distance (mm)||56 – 74||58 – 75||58 – 75||56 – 74|
|Dry Gas Filled||Nitrogen||Nitrogen||Nitrogen||Nitrogen|
|Coatings||Fully multi-coated||Fully multi-coated||Fully multi-coated||Fully multi-coated|
|Tripod Mount Screw Hole||Yes||Yes||No||Yes|
|Warranty||Limited lifetime||Unconditional lifetime||Limited lifetime||Limited lifetime|