Science

Review of binoculars Celestron Cometron 7×50

As a first binocular for young astronomers, the Celestron Cometron 7×50 binoculars are excellent. As a “don’t care if they get smashed” gamble, the second set of adult binoculars, Cometrons is second to none.

Key features of the Cometron 7×50:

Magnification: 7x
Lens Diameter: 50mm
Angular field of view: 6.8 degrees
Eye relief: 13 mm
Weight: 1 lb, 11 oz

Cometron 7×50 and its older sister 12x70s appeared in July 2013, 10 months after the discovery of Comet ISON, which was predicted to touch the Sun on November 28, 2013. this could be a spectacular sight during the holiday season. The name Cometron, a solid marketing idea, would be an accident. But, alas, comet ISON never got big enough to be seen well through cometrons. It was torn apart by titanic gravitational forces hours before reaching its closest collision with the Sun (“perihelion”).

Celestron Cometron 7×50: Design

  • Waterproof (not waterproof)
  • Porro design ideal for astronomy
  • BK7 glass is good but not great

Binoculars Celestron Cometron 7x50 in hand

Roll-up rubber eyepieces allow spectacle wearers to find their best focus point at a relatively short distance of 13mm from the exit pupil. (Image credit: Jeremy Lips and Dave Brody)

Celestron only claims that Cometrons are waterproof, not waterproof. Body elements are (minimally) rubberized. But this skin ends long before the visible joints between body parts – suspicious places for fluid to penetrate. This is one of the many compromises that allows Celestron to offer you (or your beloved child) good optics at a great price.

Prisms are of the Porro design preferred for astronomy. But they are cast from slightly cheaper BK7 glass. All other binoculars we have reviewed belong to the BAK4 model. We easily saw the difference by comparing the exit pupil of the high quality Oberwerk 8×40 (BAK4) with that of this Celestron 7×50. Instead of the sharply defined disk of light projected by the Oberwerks, the Cometrons produced a fuzzy pseudo-circle that solidified inside into a diamond-shaped (slightly stretched, rotated square) dot at the top. The exit pupil is the disk of the virtual image at the focus point of the binoculars. This is the circle you are actually looking at.)

Celestron Cometron 7×50: Functionality

  • Exit pupil more than 7 mm across
  • Intelligent field of view reproduced with factory settings
  • Ideal for use by both adults and children

Binoculars Celestron Cometron 7x50 in hand

The compact size and light weight (27 ounces) of the Cometron 7×50 means you can use them all day long. (Image credit: Jeremy Lips and Dave Brody)

In practice, this means that you must orient your eyes so that you look farther into the image circles on cometrons than on comparable binoculars made from higher quality BAK4 glass. But perhaps to compensate, Celestron’s designers opted for an optical geometry that increases the exit pupil diameter. It’s over 7mm across; unusually wide. So the practical working area of ​​the exit pupil is about the same. This provides a clear example of how optics designers can play with variable materials, processing, and design to optimize their results at their desired cost.

The large exit pupil also serves (we assume) the intended baby market. The eyes of young people are more elastic; their pupils can dilate wider than those of our old fossils. This allows children to see better in the dark and adjust to the dark faster (compensating for reduced attention span!). The wider exit pupil of the Cometron is better for younger eyes.

Celestron Cometron 7×50 Performance

  • Roll-up eyecups provide adjustment for spectacle wearers.
  • Useful for other items in the daytime
  • Dust caps do not have fixing cords

Binoculars Celestron Cometron 7x50 in hand

The wide 7mm image disk width of the binoculars more than compensates for the slight clipping of the best image area. (Image credit: Jeremy Lips and Dave Brody)

The wide dome of the starscape awaits you in a virtual exit pupil, allowing you or your child to experience the feeling of “hovering in the sky”.

If you or your young user wear glasses (especially for nearsightedness), the relatively short pupil distance (13 mm) may limit your ability to see the entire field of view. When we talk about eye relief, we mean the distance from the eyepiece lens surface to the last point where a full screen image can be seen. Lower the rubber eyecups and you can get close, but you’ll get more ambient light through your goggles and eyes. And the lenses of your glasses, I’ll kiss the lenses of your binoculars – it’s okay, as long as they don’t break.

Of course, your family can use this binoculars during the daytime for sports and nature watching. Just don’t get too close to the target. After all, cometrons are optimized for observing objects at comet distances. They will not focus on, say, a bird nesting closer to you than about 30 feet away.

Like most inexpensive binoculars, the dust caps do not have provisions for retaining cords. This means that when used by children, these caps can be far away from the lenses by the end of the first night of use without diligent parental arguing about accessories.

Should I buy Celestron Cometron 7×50 binoculars?

The small size and light weight of the Celestron Cometron 7×50 (1 lb 11 oz) binoculars allow you to use it all day long, yet you can comfortably hold it in your hands after sunset and on dark nights while watching the sky. Ideal as an inexpensive second pair for adults or as an option for young skywatchers. This pair is hard to beat at this price point. However, it’s worth noting that if image quality is what you’re after, the BK7 glass lets this pair down a bit, and stargazers might be better off opting for a pair with BaK-4 glass. However, Celestron counteracts this with a large exit pupil.

If the Celestron Cometron 7×50 is not for you

If you’re looking for affordable binoculars for kids, we think you can’t beat the Celestron Cometron 7x50s, which is why they top our list of the best binoculars for kids. But for those who want to take image quality a step further, we suggest taking a look at the Celestron Nature DX 8×32 binoculars, as it has BaK-4 glass but is still an affordable all-rounder.

Want the best overall binoculars? That title would then go to the Canon 10x42L IS WP binoculars, which we gave the highest five-star rating in our best binoculars buying guide. They have a long eye relief (ideal for eyeglass wearers), they have solid build quality, and even have built-in optical image stabilization.

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