Binoculars

Binoculars come in two two measurments – you can see them as “7×35” or “10×40”.

The first number “7x35″ is the magnification. Bigger isn’t always better because when you hold them in your hand, they magnify every shake. Binoculars with 7x or 8x magnification are best for handheld use. A 10x or 20x on a tripod would be recommended for stargazing. Avoid “zoom” binoculars with adjustable magnification, as this “trick” usually results in lower quality.

The second number “7x35” is the diameter of the “big” end in millimeters. The higher the number, the more light is let in and the brighter the image – higher weight is the downside of that setup. This is important if your hand is not steady or you have to use them all day. Large lenses also mean a narrower field of view. For bird watching, for example, the usual is 30-42 mm.

The third factor is whether they are gas tight (filled with nitrogen) or not. Better binoculars are nitrogen-filled and waterproof. After using non-waterproof ones in the rain, they can become foggy on the inside and this can leave permanent residue on the inside.