To minimize reflection on the lens surfaces and ensure clear, sharp images, anti-reflective coatings are often applied. These anti-reflection coatings are very important as part of the light that passes through any lens is reflected by the front (incident light) and rear (exiting light) surfaces. This reduces the amount of light passing through the lens and if this transmittance is very bad, the image you see will be darker than on binoculars that transmit more light. Also, the reflected light may cause ghosting and flaring, affecting image contrast.

At 8x magnification, I was also really impressed by just how little softening of the image on the periphery of the view there was and you can only just notice it by really looking for it. At higher magnification levels the amount of softening increases and becomes much more noticeable at 24x. Stars are less exciting. The dots just become bigger dots and you really need a tripod to keep them steady. But you do see more stars. Observe one that you can see with the naked eye and you do see many other, fainter ones nearby. TOKYO - Nikon Vision Co., Ltd., (Nikon Vision), a subsidiary of Nikon Corporation (Nikon), is pleased to announce the release of a new binocular model, the Sportstar Zoom 8-24x25. The Sportstar Zoom 8-24x25 binoculars feature a portable and compact body, and employ a zoom lever on the top of the body which enables smooth 8-24x zooming. The focusing ring can be operated while looking through the binoculars during observation. Comparing the view through these and that of my control compact, at 8x magnification I would say that in terms of brightness, they were almost equal, which is pretty good and equal to many much more expensive binoculars in this class. As you adjust the zoom and increase the magnification, you can actually see the image produced getting darker and darker, which is to be expected (see exit pupil above). In poor lighting conditions like at sunset, this actually has quite a big impact on just how effective and useful these zoom binoculars are. It may be obvious, but it is for this reason and the fact that they have such a small field of view that you really should not consider these Nikons as an option for binoculars for astronomy.As you would expect, keeping the image nice and still becomes harder and harder as you increase the magnification settings. At 24x I was able to the image still enough to take in all the details of what I was looking, but I had to concentrate on staying very still as even the smallest movement has a big impact on the amount of image shake. This is fine for short bursts, when you just want to take in a bit of detail, but is definitely not something that you would want to do over longer periods. Weight and especially size really matter in a good pair of compacts and obviously we are looking for a pair that is as small and lightweight as possible. This is because if the "compact" pair is too large to suit your specific requirements, you may as well just go and get yourself a similar quality mid or full sized pair of optics that by their very design will usually perform better, especially in low light conditions: At 16x Magnification:When you increase their magnification to 16x their Exit Pupil reduces to 1.56 (25/16) which means that even less light will be getting to your eyes. There is no mention in any of their marketing of them being either water or fog proof and so I must assume that they are neither. In this price range, not many binoculars are fully waterproof or fogproof and so this is fairly understandable, but it would be nice to know that they were at least a little "weather proof" - anyway I am sure that they would survive a little light rain, but to be completely safe just make sure that you don't get them really wet in very bad weather. An optional red-dot finderscope (not included) can also be attached to the rail, to help you find objects fast, if you’re aiming for a serious, tripod-based setup.

Whilst I would not expect a low cost binocular like these to have the same build quality as a top of the range pair that costs ten times as much, but I still want them to be tough enough to handle most normal bumps and scrapes and still want them to feel like you have a good quality optical instrument in your hands and not just a toy. Optics-wise they use premium glass (Schott HT) for the roof prisms with phase-correcting coating P40 and HighLux-System HLS. This makes for a pin-sharp image without the loss of contrast that cheaper roof prisms can suffer from. Lenses have reliable HDC Plus-multicoating and AquaDura lens coating for maximum protection, while anti-reflective coatings make for great low-light capabilities. At 24x Magnification:When you increased to their maximum level of 24x the Exit Pupil reduces to just over 1 (25/24) which means that not a lot of light that enters the binocular will reach your eyes. The dioptre adjustment is unusual. Rather than a dial on the eyepiece, it’s in the centre where you focus. So you focus your left eye, then pop out the dial and adjust it slightly for your right.Even with two hands, the 20x magnification makes for a wobbly image. There’s an integral tripod mount (on a rail, so you can adjust balance) which is much better. If you’re using them handheld at home, it’s worth leaning them against the doorframe for a steadier picture. Weak points? Their very narrow field of view, even at 8x magnification is really noticeable and their rather distant minimum focusing distance are definite weak points. The amount of eye-relief will also be disappointing to those of you who want to use them with glasses on. The fact that they are neither water or fogproof is also a shame, especially for those that like to use their optics in all weather conditions. As with other small binoculars, they come with a strap and a case (but the case doesn’t have its own strap). The case is simple but functional. The eyepiece cap is attached to the strap so you can’t lose it. While the objective lens caps flip down so you can’t lose them either. With their eye-cups fully retracted, they have a length of 11.9cm (4.7in), this increases to 12.4cm (4.9n) when you fully twist out the eyecups. Fully folded, the width of the binocular is 9.2cm (3.6in), fully opened it is 11cm (4.3in). Their height is 6.3cm (2.5in), which once again all on the larger end of the scale for a full compact binocular but nothing excessively so. When set to a magnification level of 8x, their field of view is 80m at 100m / 240ft at 1000 yards (4.6°) - which, for a what at this setting effectively an 8x25 binocular is not very good. To put this into context, the Steiner 8.5x26 Wildlife Pro has a FOV of 333ft at 1000 yards and the Kowa 8x25 BD has a FOV of 331ft at 1000 yards and even the Minox 10x25 BV BRW which has a magnification of 10x has a FOV of 290ft at 1000 yards.