When you buy a pair of binoculars you need to understand two numbers: magnification and objective lens size, which are always quoted on every pair as a combination of two numbers – typically 8x25, 10x25, 20x56, 25x100 and so on. If the binoculars say 8x25 then they offer 8x magnification and have an objective lens with a diameter of 25mm.
In this case, both are small numbers, so the model is a portable, everyday pair of binoculars for general use in daylight. At the other end of the scale is a pair of bulky 25x100 binoculars – so 25x magnification and a 100mm objective lens – which are thus designed for looking deep into the night sky in darkness where maximum light-gathering is critical. If it's low-light viewing specifically you're after, check out our guide to the best night vision binoculars and goggles.
The difference in weight is startling; a pair of 8x25 bins will be super light, while 25x100 are too heavy to hold for more than a few minutes. The bigger the magnification the more likely you are to get a serious shake, too. So the answer is to go for something in between. Good middle-of-the-road sizes and 10x42, 10x50 or 15x 50, which have decent magnification and can be used in all light levels. Binoculars like these are practical and can be highly impressive. About 15x is perfect for a safari.