A spotting scope is a telescope that is portable and is used for land observations. They are usually small, and the focal length is generally short, but the field of view is higher than that of binoculars. They can be useful for activities like long distance natural study, scenic observation, and bird watching. The short focal length design in the spotting scope is to ensure there is inferior magnification. Some of the issues that one must consider when buying a spotting scope include:
It is referred to as the objective lens diameter on the spotting scope and is measured in millimeters, just look at spotting scope reviews. The sizes are different and range from around 50 to 90mm in size. As the size of the aperture grows, the weight of the spotting scope would also increase. The aperture’s objective lens controls the amount of light entering into the device hence improving the quality of the object being observed. With the increase in the size of the aperture, the image quality would be more transparent and better.
It is the distance from the primary lens to the point where the image light ray come to view. The focal length is usually contained in the eyepiece and result in magnification of the image. At times the focal length may be derived as a focal ratio.
When buying a spotting scope, you need to have an idea on the different focusing techniques used on the device. There are three types of focusing techniques including rack and pinion, knob, and helical focusers. The different focusers have different applications in their field of use. The rack and pinion design are mostly used for smooth focusing, fast and common in astronomical scopes. The focuser degrades faster when exposed to external conditions like dust and humidity. Knob focusers are useful when the user needs accurate focusing and precise functions due to its slow focusing action. Helical focuser has a knurled collar knob which is fixed around the scope barrel. The focus of this design is faster and would be good to watch moving objects like birds.
A refractor and catadioptric designs are the two standard optical designs used. The significant difference between the two is the type of materials used to make the optical lens.
The refractor uses a glass lens to bend light. A refractor is a long tube on the spotting scope which has an eyepiece on one side and an objective lens on the other end. There are various refractor designs on the market, and one example of the design is the image erecting prism type. It is common for hunters since it allows for the correct image location. The refractor for hunters has a short focal length which ensures that they are lightweight and also have a broad field of view.
This design of the optical view uses mirrors to reflect light into the system. It uses several mirrors to focus on the particular image. It has a long focal length that allows it to be folded into a compact tube. This design has a high magnification capability than the refractor design spotting scope.
The eyepiece of a spotting scope is also a vital factor to consider when selecting the spotting scope. The eyepiece assists in enlarging images at far distances and show the pictures on the eyepiece. There are various eyepiece designs for different scopes in the market where some are variables, fixed focal length and others give a full field of view.
Therefore, this spotting scope buying guide highlights some of the key features to look at scope before purchasing. The prices for the different scopes would be different, and different manufacturers manufacture the spotting scope.