Celestron 71008 SkyMaster 25x70mm Porro Prism Binoculars with Multi-Coated Lens, BaK-4 Prism Glass and Carry Case, Black

Product Information

This range of high specification porro prism binoculars are made in the USA using the best quality Japanese optics ensuring the highest quality view. Designed for long range glassing and astronomy they are currently available in three configurations. Light Gathering and Low Light Performance Performance– Testing in various lighting conditions, especially low light

I’ve tested them under a variety of lighting scenarios, with a focus on their performance in dim conditions for stargazing. Porro prisms are arranged in a certain way with the benefit of providing greater depths of field and wider field of views compared to other “Roof Prism” equivalents. Magnification and Light Gathering Ability Compared to an 8x42 binocular that can have a near focus of around 6ft, the close focus of these seems very far away, but focusing on near objects is not really what these long distance binoculars are about anyway. These and all other 25x70 binoculars produce an exit-pupil that is 2.8mm in diameter (70 ÷ 25 = 2.8), which is fine during the day and in good light when that will pretty much match that of the size of the pupils in your eyes and so provide them with enough light so that you see a nice bright image. The Zhumell Tachyon 25x100 and the Celestron SkyMaster 25x100 on the other hand also have 4mm exit pupils (100 ÷ 25 = 4) and you still get the added reach and image detail with the 25x magnification. However the huge trade off is the increased cost, size and weight (se table above).We also measure the Power with our systems which is essentially the error from the reference sphere to the test optic. The reference sphere we use on our system is a very high quality sphere so the closer to zero the Power, the less error between the 2 elements thus ensuring a higher quality optical surface. So, ’20×80′ binoculars give you 20 times the magnification of the object viewed by the naked eye, and achieves this with front lenses that are 80 millimeters in diameter. It is basically the true angle that can be seen when looking through the optics. It is measured in °. Top quality optics and coatings have been used throughout and this includes: Fully Multi-Coated Optics and BaK-4 Prisms that have phase correction and the very best dielectric high reflectivity coatings on them.

Both of these numbers are crucial to understand, because they indicate what you will be able to see and in what level of detail. There are currently four models within the Cavalry range. All use BAK-4 porro prisms and come with fully multi-coated optics and are designed to be especially rugged to withstand the extreme elements.The Celestron SkyMaster 15x70s offer excellent value for their price. Although they may occasionally have misaligned prisms, similar to the 25x70s, the lower magnification is more forgiving of such issues. It’s still essential to replace the included plastic tripod adapter, however, and using these binoculars with a tripod or monopod will significantly enhance your experience given their weight and the 15x magnification. Celestron SkyMaster Pro binoculars are also tripod mountable and in the case of the 15x70 model comes a very good quality metal adapter that includes a RSR (Reflex Sight Ready) rail attached to the top of it, whilst the 20x80 SkyMaster Pro has a permanent tripod mounting bar fixed to it with the RSR rail and thus does not require an adapter.

Both models have a single centrally located focus wheel and right eye diopter adjustment. This is interesting and certainly benefits those wanting to also use the binocular during the day and focus on nearer objects as many astro binoculars employ an individual eyepiece focus mechanism and thus have a diopter adjuster on each eyepiece and no central focus wheel. Both of these lenses work together to collect light and send it toward your eyes to present the image you are trying to observe. Build Quality and Ergonomics– Reviewing material quality, weight, balance, and comfort during extended use Improving on an already winning formula can be tough and in some cases does not work. However, with the inclusion of high-quality ED glass, I think Celestron have managed to pull it off with their newer TrailSeeker ED range.

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What's also cool is that you a Binocular Harness comes free with these. Something that I have hardly ever seen any other brand offer before and think is really a great idea. The product that you do finally choose depends on your interest level – for beginners we recommend the SkyMaster 15x70 or the SkyMaster 12x60, whilst experts will prefer the SkyMaster 25x100. Celestron has designed and engineered the larger SkyMaster models like the SkyMaster 25x100 to meet the demands of extended astronomical or terrestrial viewing sessions. However, for these extended sessions we recommend that you to use a tripod as these binoculars are quite heavy, weighing in at 4 kg. Amongst the lower-end models, the SkyMaster 15x70 is probably the most popular. It is available at an affordable price and is both versatile and lightweight. The Exit Pupil is calculated against the dilation of an eye’s pupil once it has become dark-adapte

Celestron do not expand on the exact makeup of their compound objective lenses so I cannot comment, but we can examine how their 70mm diameter, combined with the 25x magnification affects their potential light gathering ability and how well they are likely to perform against others in poor light and at night: Whilst the Trailseeker series sits under the headlining Granite's and cost substantially less, they share many of the same high quality materials and optical coatings. This Celestron SkyMaster binocular that I tested, comes with a 10 year UK guaranty and the booklet has details of the limited lifetime warranty for US and Canadian customers.

Celestron has also designed and engineered the larger SkyMaster models to meet the special demands of extended astronomical or terrestrial viewing sessions with maximum stability and secure optical alignment, the 80mm and 100mm SkyMaster models feature enhanced structural reinforcement to the main binocular body. The highlight of this series is the large aperture, which allows a correspondingly large amount of light to enter the optic and, in dark-sky environments, even celestial objects like galaxies and nebulae are within viewing range. The binoculars also feature long eye relief, making them ideal for those who wear eyeglasses. The older, non-ED version of the TrailSeeker (see below) is one of Celestron's real success stories, combining a high level of performance with an affordable price tag. This balancing act is certainly not easy and thus going one step further and improving on an already winning formula often does not work. As you will see from the specification table above, the 20×80 SkyMasters give you a greater Angle of View (3.2°) compared to that of the 27×70 SkyMasters (2.7°)