Spotting scopes are used by birders to take advantage of their powerful magnification capabilities. Spotting scopes generally operate in a range of 20x to 60X magnification. At 60x, an object looks 60 times closer than it does with the naked eye.
There are two basic designs for the viewing angle. There is no difference in the quality of image and the final choice is one of personal preference.
In some designs, the eyepiece and the barrel of the scope are in a straight line.
This is a good choice if you do a lot of birding from the car, using a window mount.
Image from Carl Zeiss Optical .
This eyepiece is at a 45 deg. angle to the barrel of the spotting scope.
When mounted on a tripod, this design allows the tripod to be at a lower position, providing a more stable platform.
Image from Kowa Optimed, Inc.
The amount of magnification is based on the eyepiece. The range is usually from 20x up to 60x. In general, the higher the magnification, the lower the image quality.
The individual eyepieces can be expensive.
Alert: Spotting scopes can be sold without an eyepiece. When purchasing, make sure the eyepiece is included with the purchase.
Some birders feel the fixed magnification eyepieces provide a slightly better image than a zoom eyepiece. Others prefer the convenience of the zoom.
If you are purchasing a top-of-the-line spotting scope from companies like Zeiss, Swarovski and Kowa, zoom eyepieces will deliver excellent image quality. Prices range from about $1500 to $2000 for these high-end units.
If you are considering a lower cost unit (as many of us do) with a zoom lens, try to test the unit before purchase to make sure the image quality is acceptable to you.
Eyeglass wearers - be sure to determine that the eyepiece selected is 'eyeglass friendly.' There are several designs available, including some very poor ones.
The brightness of the image is based on several factors, including the type of glass used in the lenses, lens coatings and diameter of the objective lens (the front end of the scope).
Unless you have a Phd in optics, all the special names used to describe the type of glass and coatings used by the different manufacturers is really of little value. Great marketing, but very few have the knowledge to really judge the difference between one type of lens coating and another.
The diameter of the objective lens is something we can all judge. The larger the objective lens, the brighter the image. Objective lenses are measured by their diameter in mm. The range runs from about 50 mm to almost 90 mm in a typical spotting scope used for birding.
The downsides to the larg...