This short document explains some of the different terminology that you will come across on different spotting scope websites. Some of it may be confusing at first, but I will try to break it down here in as simple terms as possible. I hope you find it helpful!

A spotting scope's resolution tells you how clear an object will look when viewed. Resolution depends on the diameter of your objective lens. The bigger your objective lens is, the sharper the resolution will be. Other items also come into play such as glass quality, prism quality, and lens coating, but the main determinant of resolution is the lens diameter.

As mentioned above, objective lens diameter is important. The objective lens exists to gather light and direct it to the prism or eye piece. The wider the diameter, the more light will reach your eye, giving you a sharp and well lit image. On the negative side, wider objective lenses are bulkier and will weigh the scope down. There are two sides to the coin, but you will discover that there are lots of lens diameter that can meet your preferences.

Porro prisms are prisms that are used in spotting scopes, just like they are used in binoculars. Additionally, they can also be used from different quality glass.

Optic coating is used to minimize light reflection and loss when light shines on the scope's glass surfaces. When you read terms like "multi coated" or "fully coated", this means that there are multiple layers of coating used on both the inside and outside of your lenses.

Exit eye pupils measure how much light can be used by Winchester spotting scopes. Usually, bigger exit pupils will give you brighter images, especially in low light situations. You can figure out the exit pupil size by taking the objective lens diameter and dividing it by the magnification. Lens coatings and your eyes can affect how well scopes perform at dusk and dawn as well.