Celestron 15-35×70 Skymaster Zoom Binocular

Many years ago I bought my wife a Celestron C-90 spotting scope (equivalent to a straight 1000mm, f11 lens) with a aluminum Celestron case and additional eye pieces as one of her Christmas gifts (it was a lot more back then, then it is now). Since it has held up so well, and being that the Celestron brand has been around so long, I thought I would give these binoculars a try. I purchased them for $108.53 flat via Amazon Prime, versus the full retail price (MSRP) of $169.95. The general ‘street price’ is around $125 – $130.To start with, if you don’t know optics, this set has a extremely small field of view (FoV), so be warned that they must be used with a tripod or other fix placement device. Being within the “Ultra-narrow FoV” range (denoted as 1 to 3 degrees), at 1.25 degrees this set will only have a FoV of 65.45 feet in diameter at 1,000 yards (1 degree of Arc equals 52.35987755 feet at 1,000 yards). Because the FoV is so small, and the binoculars are so long, the points of viewing interest will need to be fairly stationary or you may find it rather difficult to track. Additionally, you should also understand that these are not actually astronomical binoculars (although they could be used for that, with limited results, like examining the Moon) as true astronomical binoculars (sometimes called “binocular telescopes”) will never have ‘zoom’, nor a central focus ring, and the 71020 in common use is generally restricted to terrestrial viewing in broad daylight. Note: If you actually want a real pair of astronomical binoculars, you would start at 25×100 (Celestron makes this) on up through 25×150 (Fujinon used to make this). The light gathering at extreme magnification will always be dampened by physics (which you can’t get around, unless you make the objective lenses even bigger, and then the price will become ‘astronomical’), and if you were to add ‘zoom’ to the mix, that would only make it worse.The objective diameter is the width in millimeters of the first lens (of which there are 2 in this case, because they are binoculars), and determines the light-gathering ability of the optical instrument by how wide they are. In this case it is 80mm, so the light gather properties of the 71020 are very good in that regard. Most modern optical instruments also use anti-reflective coatings on the lenses and interior barrels to reduce light scatter and enhance the photon quantity delivery to the eye, as is the case here. Additionally, any ‘multi-coat” process is critical in its application (too thin, too thick, not evenly applied, etc) to the end result image one will see. It is in this arena that optics will tend to pass or fail when it comes to the quality of image for consumers, but you won’t be able to specifically place the blame on it without lab equipment. Finally, some of the benefits of these large lenses are undone in this case due to the fact that this is a ‘zoom’ binocular set (which would apply to all zoom binoculars).The prism’s used (to shorten the length of the instrument and correct the orientation of the image) are the industry standard “BaK-4”. Genuine “BaK4” (which designates “BaritleichKron [“Barium Crown” in English] process 4, glass”) prisms are better than “BAK-4″, as is the cheaper, Chinese way of manufacture. The difference in slipping from what it is attempting to copy may show up as a slight ‘milkiness’ in the image (because it is not actually ‘barium crown glass” but rather “phosphate crown glass”). When you start paying more than $400 for binoculars, then you will have a right to complain about the hucksterism, but for this level/cost, it is acceptable IF it is even actually “BAK-4”. The 71020 has “BaK-4” (small “a”) printed on it, but at the same time I believe the 71020 is manufactured in China, …so, who knows? I just thought everyone should be aware.The EP (Exit Pupil) is extremely small at 3.2mm. Any optics having a EP under 4mm should effectively be used in only bright daylight conditions. 4 to 6 is average, 6 to 7 is superior, and 7 and beyond is super bright. With the 71020 having a RBI (Relative Brightness Index) of 10.24 it is rather dim (a RBI of 25 is standard). But, both of these factors are to be expected to a degree in this configuration of binoculars, especially at such a low price point.The spine (or “spar”) is solid, and along with its large tripod attachment knob, will give it good stability against shake and lend confidence in grasping the pair while moving it.Surprisingly, the objective lens caps actually stay in place until removed, which is a good thing. Now if they would just repeat that on the protective eye-piece cap.The following are the actual dimensions of the 25-125 x 80 Celestron SkyMaster binoculars, Model 71020, and are given for those who might wish to buy or construct a hard storage container for this binocular instrument. The soft-sided, velcro-closing, nylon bag with nylon carrying strap that comes with it just ‘seems wrong’ when it comes to any type of actual protection, other than dust, so -The Celestron product box it comes in is 16 1/8″ tall by 10 7/8″ wide by 7″ deep, which uses a 2-piece closed-foam insert to protect the binoculars.This product box also comes inside a Celestron shipping box that is 17 1/2″ tall by 11 7/8″ wide by 7 3/4″ deep.The exact manner in which these binoculars are stowed will determine the internal dimensions required in a hard case.As this set has a integral tripod mounting system (which can twist, or have its securing knob removed), along with the fact that the binoculars can ‘fold’ slightly for pupilary distance adjustment, the dimensions are actually variable for storage.The EXACT dimensions are -Height A: 13.500 inches (13 1/2″ or 342.900 mm) with no caps in place, and eye relief down.Height B: 13.750 inches (13 3/4″ or 349.250 mm) with all caps in place.Width A: 8.5625 inches (8 9/16″ or 217.487 mm) when ‘folded’ (dual eye protection cap does not fit properly when binoculars are ‘folded’)Width B: 9.125 inches (9 1/8″ or 231.775 mm) when ‘unfolded’.Depth A: 4.000 inches (4″ or 101.600 mm) when ‘folded’ and the tripod retention knob is removed.Depth B: 4.4375 inches (4 7/16″ or 112.7125 mm) when ‘unfolded’ and the tripod retention knob is removed.Depth C: 4.750 inches (4 3/4″ or 120.650 mm) when ‘unfolded’ and the tripod retention knob is left in place.So according to my EXACT measurements -The very smallest interior dimensions of a hard case would be by using Height A, Width A, and Depth A, which amounts to:13.5 inches by 8.5625 inches by 4 inches (462.375 cubic inches) [but you can not use the dual eye protection cap].The very largest interior dimensions of a hard case would be by using Height B, Width B, and Depth C, which amounts to:13.75 inches by 9.125 inches by 4.75 inches (595.976562 cubic inches)…So it all depends on how you configure the binoculars for storage that will determine what size hard case to acquire. Personally, I’d go with the larger case, so the protection caps can be used.If you concur, you might check into the Pelican “1485 Air” case w/ foam (about $161), or the Pelican “1450 Protector” case w/ foam (about $94), but these can be expensive.You might just take the 2 very same closed-cell foam inserts that come in the box and use them inside a hinged (2″ down from the most expansive face) wood or Starboard box you create for yourself with the interior dimensions of 15.5″ by 10.5″ by 6.5″. This would obviously require time and effort.All-in-all, the low price versus quality, I regard these as a very good buy. I give it 94 points out of 100, and would recommend it for purchase, with the full understanding of what you are buying and how they can actually be used (resulting in genuine/realistic expectations). If you have boat loads of money, by all means, buy a $6,000+ professional set of top-end astronomical binoculars …and develop ulcers over protecting them in storage, transit, use, and against theft. The 71020 is not that pair. This pair you can have fun with …as long as you remember to bring the tripod.

Its amazingly powerful. Moon is very large & its craters are very very clear. Though its sharpness decreases at highest zoom but I liked its performance.Warning: don’t try it on a cheap tripod, someone advised me to buy Ravelli APGL4 new professional 70″ tripod, I bought it from Amazon and both are perfect. The binocular is heavy & should not be mounted on cheap tripods.I attached the images of Binocular, tripod, also one example for how 25X , 125X zoom look like…..The Moonshot is un-cropped image taken by a 10mp Dslr camera thru the binocular. Please ignore the focus, it was very difficult.

Hi, after doing a lot of study i finally bought the Celestron 20-100X70, zooming till 50 to 60 k is good but the objects are not clear after this, because of its size its difficult to use it without a tripod, i am shopping for a suitable tripod for mounting this with a budjet of 2 to 3,000 rs ..please let me known if any one of youall have purchased it..Venkatesh Mumbai 28-1-2017

Excellent binocular. I did not find the zoom that useful (yet) . However I have not used it with a tripod. Speaking of tripods, unless you are a semi professional bodybuilder or weightlifter this is not usable for astronomical observations without a tripod – the magnification is too good and hence magnifies the slightest shaking, which will happen for a normal person whenever you point it skywards.. However terrestrial observations are manageable without tripods and the details you get are amazing. I was able to discern details of a tree and a house at least half a kilometer away while on a bird watching trip.

Great binocs especially for stars or clusters etc. Awesome to have the zoom built in. They are big and heavy so planets, the moody or fairly close terrestrial objects are hard to watch because it is hard to keep the binocs steady unless you have a tripod for them.

Justo lo que requería, llego muy bien empaquetado y protegido, además es un buen producto con un gran alcance y excelente calidad de imagen, el único inconveniente es su peso pero con la ayuda de un soporte o trípode me las arregle.

I just received this and, as previously noted, they are quite light for their size. Perhaps that is why when mine arrived they were non optimal. I immediately notice that I get double images (with one higher and to the side) of the other and this is especially bad the higher the magnification. I am going to return them because I had given this as a gift to someone else a few months back and they did not have this issue at all.