Roof prism binoculars in Celestron’s new Nature DX line provide surprisingly good performance for the price.
Celestron has long had a reputation for offering excellent binoculars for astronomy, a legacy of Chairman Emeritus Alan R. Hale’s personal interest in binoculars. Many years ago he wrote a fine buying guide, Sport Optics, and before that the book How to Choose Binoculars.
Continuing their corporate commitment to binoculars, Celestron has expanded their series of Nature DX roof-prism models. Jamie Carter and I each favorably reviewed Celestron’s earlier Nature DX ED 50mm binoculars, in separate group tests you can find on AstroGearToday: here, for Jamie’s test of the 12×50 DX ED, and here for my test of the 10×50 DX ED.
While the latest models are also labeled Nature DX, they are not ED. Be careful about noting the distinction; it is a slight difference in the name easy to overlook when shopping. While the new non-ED models cost less, they lack the higher grade of Extra-Low Dispersion or ED glass of the more premium models, which provide better color correction.
While the new Nature DX series also includes 32mm, 42mm and 56mm models, I tested the DX 10×50, as that’s a combination of magnification (10x) and aperture (50mm) ideal for handheld stargazing. I tested a sample unit sent to me by Celestron.
The new Nature DX 10×50 sells for about $50 less than the $250 Nature DX ED 10×50. I was curious to see if the economy model gave up too much in quality. I was pleased to see it did not.
Optical Quality
The DX’s lenses are fully-multicoated and the interior barrels well blackened for excellent light transmission and little lens flare. Only when looking at the Moon was some slight flaring and ghosting visible, common in many binoculars.
Surprisingly, when looking at bright celestial targets such as Venus, Jupiter, and Sirius I could see no obvious false color fringing in the form of blue or magenta halos. Only on the Moon could I detect the very slightest color fringing on the lunar limb on either side of focus. In focus, though, the Moon was colorless. This was superb performance for a non-ED binocular, especially at its price point. I’ve seen obvious false color in non-ED binoculars costing more than twice as much as these Celestrons.
Star images were sharp across about 75% to 80% of the field, distorting only in the outer portions of the field due to astigmatism and coma. But the level of aberrations was well controlled; stars didn’t flare excessively at the edges. Only the very finest and most costly binoculars are sharp to the edges.
Center sharpness was also very good, competing with the best 10x50s I have tested, such as the $400 Athlon Midas G2 10x50s I reviewed for AGT here. Stars snapped into focus with no mushiness or elongated images from astigmatism.
There was no darkening of the edge of the field and the eyepiece field stop appeared quite sharply defined, unlike some binoculars where the outer edge of the field fades into a dark and fuzzy blur. The field was flat, showing very little barrel or pincushion distortion that would warp the field when scanning back and forth.
The main optical drawback is the narrower field of view compared to many other 10x50s. The Nature DX is specified as having eyepieces with a 58° apparent field, which at 10x yields an actual field of view of 5.8°. I measured this with star fields and the spec proved accurate. The higher priced Nature DX ED has a similar field of view.
However, an apparent field of 63° to 65° is now common for 10×50, such as the Nikon Action Extreme EX, a Porro prism model, my favorite among several 10×50 Porros I’ve tested in recent years. I compared the Celestron to the Nikon, and while that slight difference in field doesn’t sound like much it was enough to make the view through the Nikon a bit more impressive. Stars did distort more at the edge in the Nikon than in the Celestron, though.
What I did not see when switching back and forth between the Nikon and Celestron was any noticeable difference in image brightness or contrast despite the conventional wisdom that Porro prism binoculars are brighter than roof prism binoculars. The faintest stars and wisps of nebulosity in Orion’s Sword were equally visible in both binoculars.
The Nature DX models are said to have phase-correcting coatings on their prisms, without which roof prism binoculars do produce dimmer, hazier images than Porros. But these days it’s rare to find a roof prism model without phase-correcting coatings even in an economy model like the Nature DX. So, any optical advantage Porros once had is going away.
In short, for its $200 cost the Nature DX provided excellent optical performance.
Mechanical Quality
The DX’s wide ribbed and rubberized focus wheel turns smoothly and precisely even with gloved fingers, and with the binoculars (and fingers!) subjected to sub-freezing temperatures. The narrow 12cm (4.7-inch) width of the binocular makes the focus knob easy to reach.
The right eyepiece diopter adjustment was stiff, which is good in that once set it won’t shift. But making the initial adjustment for any focus difference between a user’s eyes is difficult, as turning the diopter shakes the binoculars, making it hard to precisely focus for the right eye.
The rubber eyecups twist up to a choice of two raised positions: a mid-point click stop and fully raised. With the eyecups twisted down to their lowest position, seeing the entire field with glasses on was no problem. Eye relief is stated as 17.5mm and that also proved accurate.
Behind a fiddly screw-off cap at the front of the bridge is a 1/4-20 bolt hole for attaching a tripod adapter. However, the adapter has to be a thin unit (such as Celestron’s accessory here) to fit between the closely-spaced barrels.
The tethered front and rear caps are pliable rubber, not stiff or flimsy plastic, and so should stand up to long-term use. The polycarbonate body is said to be dry nitrogen filled and waterproof, a claim I did not put to a torture test.
The Nature DX 10×50 weighs 824 grams (1.8 lbs), about 40 grams lighter than the 10×50 DX ED and a noticeable 218 grams lighter than the relatively svelte (for a Porro) Nikon Action Extreme EX, and much lighter than the big and hefty Oberwerk 10×50 Deluxe Porros I reviewed here that tip the scales at 1173 grams (2.6 lbs). It’s easier to scan the skies with handheld binoculars when they are lightweight.
If you are looking for a light, economical and compact binocular good for all purposes, especially one well suited to stargazing, I can recommend Celestron’s new Nature DX 10×50. When you can get them — the new Nature DX models were not yet listed at many dealers at the time I prepared this review.
Plus
Excellent sharpness
Negligible chromatic aberration
Smooth focuser
Good eye relief
Minus
Slightly narrower field than competing models
Slight ghosting on the Moon
Stiff diopter adjustment
Lack of availability at the time of review
Approximate Retail Price: $200
Website: www.celestron.com
