Expandable spotting scope is a very rare type of spotting scopes. These scopes are very convenient for long-distance observations of hunters and hikers that needs bigger magnification but less weight and size for easy carrying around. The body of these scopes can be folded and easily stored into backpacks. Due to its folding mechanism, these scopes usually aren’t sealed and filled with dry gases that makes them waterproof and fog-proof, thus less durable and protected. The internal optic glass that moves due to folding mechanism has usually trouble aligning perfectly, making the view-through less sharp and more distorted. This straight-through design is mostly suitable for observations below your own level by hunters and hikers in the mountains and less suitable for bird watching and astronomy.