Spotting Scope Terminology

Celestron VistaPix IS70 Digital Spotting Scope and Camera – All-in-one 70mm digital spotting scope with 3MP digital camera.

The spotting scope you choose greatly affects how it will work for you under certain conditions. For example, the person who only wants to use his or her spotting scope at the rifle range can often drive up to the bench and conveniently layout supplies including a large objective porro prism spotting scope. The target shooter could easily use a 80MM porro prism scope on a full-length tripod and not worry about compact design or lightweight since their automobile is a few yards away. On the other hand, a person who is planning an elk hunt in Montana’s Bob Marshall Wilderness is probably very concerned with weight and the ability to fit the scope into a pack. Typically roof prism spotting scopes offer the hunter or backpacker a more compact and lightweight design to pack and carry long distances. While some porro prism spotting scopes are quite compact, others can offer larger fields of view and resolution, but they may not be practical to pack into the woods. Other features for the hunter to consider are rubber armoring to protect the scope from blunt force. A waterproof spotting scope offers piece of mind to the hunter working in rain and snow.

**This is not a comprehensive list of all the factors to consider when choosing a spotting scope but it will hopefully shed some light on some of the more critical factors to consider.

Magnification: The magnification feature of a spotting scope allows the user to view an object much closer than it would otherwise be using only the human eye. The magnification power is a function of both the scope’s optical system and the eyepiece being used. Spotting scopes such as Bushnell’s Spacemaster® series and Bausch & Lomb’s Premier® HDR series offer the user a choice of zoom eyepieces such as a 15-45x variable eyepiece or high power fixed eyepieces such as 60x. Most hunters prefer the versatility of a zoom (variable) eyepiece for use at varying distances. Sometimes the higher magnification offered in a zoom eyepiece can make the difference between positively identifying a trophy animal and not knowing for sure whether this is the Boone and Crockett animal you’ve been tracking.

Objective Lens Diameter: The objective lens of a spotting scope serves to gather incoming light. A 60mm objective lens will gather more light than a 50mm lens. When more light is transmitted to your eye, you will view a brighter and clearer image. Resolution (ability to see detail) is also a function of the objective lens diameter.

Eye Relief: Eye relief is the minimum distance between the spotting scope eyepiece and your eye that still allows you to see the entire field of view. Hunters and shooters who do not wear eyeglasses can use most spotting scopes and eyepieces without any trouble. People who wear eyeglasses are more concerned with eye relief. When a person wears glasses while looking through a standard spotting scope eyepiece their glasses may touch the eyepiece. Bushnell offers two eyepiece enhancements for those users wearing eyeglasses. Most Bushnell® and Bausch & Lomb® spotting scope eyepieces offer the ability to roll down the rubber eyecup thus increasing the distance between your glasses and the eyepiece without impairing the view. If even more eye relief is required specially designed long eye relief zoom eyepieces are available. The need for eye relief is an individual specific need. Sometimes eyeglass wearers are more comfortable looking through a spotting scope without their glasses on.

Optical Lens Coatings: Lens coatings play an important role in getting the light gathered at the objective end of the scope transmitted through the ocular end to your eye. The lens coatings are partially responsible for delivering a brighter and higher contrast image. All Bausch and Lomb® spotting scopes offer multi-coated lenses for superior images. Bushnell® spotting scopes feature fully coated lenses.

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