Celestron SkyMaster Binoculars 15x70

 

 

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This posting begins with a discussion of some core information about binoculars for astronomical viewing that should help potential purchasers make a more informed purchase decision.

If you have other viewing objectives than astronomical objects, or are already familiar with binocular specifications, you may want to stop here or just read the latter part of this review before going on to other postings; otherwise, read-on.

There are two main styles of "true" binoculars. Here, binoculars that do not use prisms such as opera glasses, are not discussed further. Most binoculars use one of two type prisms, either roof prisms or Porro prisms. Roof prisms are more modern and have a straight through appearance, i.e., the binocular cylinders form straight tubes. Porro prism binoculars (named after Ignazio Porro) have a tell-tale right angle bend. These usually are manufactured with two prism on each side of the binoculars, i.e., double Porro prisms. Although considerably larger in size, because of their improved optical qualities Porro prism binoculars, such as the model reviewed here, are preferred over roof prism binoculars for astronomical viewing.

Another important aspect of binoculars is the size of their exit pupil. Younger folks have pupils that can open, dilate, to a maximum size of slightly over 7mm. However, as one gets older the size of this window into the eye reduces. Over the age of thirty most folks have a reduction in their dark adapted pupil size of approximately 1mm every 20 years. The exit pupils for a pair of binoculars should ideally approximate the entry pupil of the observer's eye. Although some studies suggest an even smaller exit pupil size, see below. The size of a binoculars' exit pupil is found by dividing aperture by magnification. For example, common 7 x 50 binoculars (7 power by 50mm) have an exit pupil of approximately 7.14mm. In practice, this exit pupil size is larger than many adult's dark-adapted pupil size, particularly when some extraneous light is also present. In most viewing environments such as in or near a city such extraneous "light pollution" is almost always present. In addition, the periphery of the eye's lens exhibits some inherent optical degradation. Thus, an exit pupil size around 5mm may be preferred, although some experimental evidence suggests an exit pupil even less than 4mm may be most appropriate. These 15 x 70mm binoculars have an exit pupil of approximately 4.7mm resulting in more of the light exiting the lenses entering the eye than might occur with e.g., 7 x 50mm binoculars.

One of the most important considerations when choosing binoculars is their light gathering ability. Binoculars are essentially "light buckets". The human eye at its widest has a 7mm plus entry window. The 70mm objective lenses here have over 50 times the light gathering area of the human eye. Another factor affecting the light transmitted by binoculars are the materials used in their lenses and lens coatings. The least expensive binoculars have uncoated lenses or single coated lenses. Multi-coated binocular lenses and BaK-4, barium crown glass prisms, as in these Celestrons, are typically more expensive but improve light transmission resulting in sharper and brighter images.

The best eye relief, i.e., the distance your eyes needs to be behind the exit pupil of a binocular to see the full exit image is probably between 15mm and 20mm. These binoculars provide 18mm and additionally come with rubber eyecups. Thus, I've been able to use these both with and without glasses. I use lightly tinted sunglasses when viewing the moon to see more detail. In this case I leave the eyecups raised. When viewing without glasses I leave the eyecups down.

In use, I've found the images sharp and with adequate contrast to enjoy star clusters, the moon and planets. This pair's primary negative is its size and weight. These binoculars are really big. Owing both to their size and weight and as well as the relatively high magnification they are not comfortable to use hand-held for any but the shortest period of time. Because of their magnification, the slightest shake moves the astronomical object out of the field of view. Fortunately, they come with a tripod adapter. However, for some the need to use a tripod may defeat the value of having a "portable" pair of hand-held binoculars. For these observer's a smaller 50mm binocular is more appropriate. A minor problem is the carrying case, mine arrive with missed stitching on about a 1" section of a vertical seam, letting light through and possibly rain. The case is also a bit tight making it more difficult to easily insert and remove the binoculars, a better degree of quality control for the case, and a slightly larger size would seem more appropriate. Simply holding the case to the light and looking inward will reveal any stitching missed.

However, even recognizing that these binoculars cannot be hand-held for any extended period, they are probably one of the best choices for astronomical observers who need relative portability compared to a probably more cumbersome and expensive telescope. Perhaps surprisingly, they are also an extremely useful adjunct for those who use telescopes.

In summary, these binoculars allow for considerable additional exploration of astronomical objects compared to the naked eye. However, a tripod is required for any extended observations. Highly recommended.

With this pair of binoculars you should get some great views of the moon and should be able to see plenty of stars, though when I tried them I couldn't see many for the full moon and clouds, it's been cloudy every night since! For the price you get a remarkably sharp image, focusing is easy and attaching the mount is a doddle (the front cap of the central pivot unscrews), but that flimsy plastic mount is the only let-down really; it needs to be made of sturdy metal to be of any use, otherwise it just gets the wobbles. The mount can be re-enforced by glueing metal rods into the grooves on either side; I can't help thinking that if these grooves were full of plastic then the wobble wouldn't be nearly so bad, if there at all, so filling them with some kind of resin is also an option.

The construction seems very solid, rubber armour all over with plenty of grippy surfaces to get hold of. The fabric bag they come with isn't up to much, would have preferred a hard case, but I suppose it would be serviceable for carrying them and protecting them from some light rain. Probably better off attaching a proper wide camera strap than the thin one that comes with these.

I repeat what others have said - these are too heavy to hold up by hand without some sort of support, either rest your elbows on something or (preferably) use a tripod or pole.

One word of caution for anyone buying binoculars for the first time - get some expert advice in a camera shop that has a good selection of binoculars, or try a friend's pair. Make sure that you have the eyes for binoculars, as some people (myself included) simply cannot look through them without seeing two images due to irregular eye sight; I wear glasses, and although they are weak it is enough to make binocular viewing impossible for me.

I will be returning my pair for this reason only, using the excellent Amazon returns facility, and purchasing a monocular instead.

They are nice for the money. I do like mine. Despite what you read dont try 15x70 binocs hand held unless if you are Data from startreck. Yes it can be done, but the vibes mean you lose alot and it aint that comfortable. Tripod mount it. The bracket they supply is a joke though. Plastic and flexes to much. You will need to order a proper one - solid metal - which wont flex.

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4.0 out of 5 stars First Binoculars
Delighted with these, my first binoculars. I bought them for night sky viewing and they are great. Only minor complaint is that they are slightly too heavy for me and I probably... Read more

Published 4 days ago by Ruth32

3.0 out of 5 stars Celestron SkyMaster Binoculars 15 x70
I have only just received these binoculars, so cannot comment much on them, but one thing I am quite disappointed in is that in the instruction leaflet that comes with them, it... Read more

Published 9 days ago by jazzejeff

5.0 out of 5 stars celestron skymaster 15x70
looked at loads of different binoculars.wanted for starting out in astronomy,these binoculars are excellent,had one clear night so far,detail on moon very good,viewed one of... Read more

Published 11 days ago by andypandy

5.0 out of 5 stars Celestron 15X70s
Most impressed with these binoculars. Have mounted them on a very sturdy mount in my observatory and have been using them regularly. Read more

Published 14 days ago by gemini 3

5.0 out of 5 stars I love them.
I love these binoculars, nothing much more I can add. Bit wobbly on the tripod though, but nothing major. I can live with it.

Published 16 days ago by Charlie

4.0 out of 5 stars Brilliant for us 'newbies'
I have no knowledge of astronomy, but my husband was showing an interest and it was his birthday, so I purchased these after reading the reviews here. Read more

Published 2 months ago by T. Peters

4.0 out of 5 stars Celestron 15x70
Purchased these binoculars to star gaze as the the price is quite good . On receiving them i discovered that the collimation was out , probably badly handled by the courier... Read more

Published 3 months ago by A. Ryan

4.0 out of 5 stars Nice astronomy binoculars
Probably...the best option to choose if you're looking for astronomy binoculars. It gives to you good brightness with a wide FOV. Put it yor basket!!!

Published 3 months ago by Miguel MMartin

4.0 out of 5 stars Great product - very happy!
Having read conflicting reviews, I cautiously purchased these binos, they arrived and... Brilliant!

Very robust, good quality and well designed, they look good too. Read more

Published 4 months ago by Mr. J. P. Sibley

5.0 out of 5 stars excellent tool
These binoculars are one of my best buys in the last years. Just perfect for stargazing. Not too expensive, quite more powerful than the typical 10x50's and even the 10x63's. Read more

Published 4 months ago by Vasco

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