Crop (cropping): Digiscoped images that have been transferred to a computer can be "cropped" by trimming the image with special software, such as Adobe Photoshop.

Afocal photography: Digiscoping is considered to be "afocal" photography because the camera replaces the eye as the first lens receiving the image.

Digiscoping: A form of photography that combines a digital camera and a birding spotting scope.

Depth of field: When a camera focuses on a distant object, all the objects at that distance are sharply focused. Elements not at the same distance are out of focus and will not appear as sharp in a photograph. The human eye cannot distinguish between very small degrees of "unsharpness." Some objects in front of and behind the subject may still appear sharp. Generally the closer they are to the subject, the sharper they are.

Images with a "deep" depth of field tend to maximize the distance from which the auxiliary image elements can be from the subject and still remain sharply focused.

Images with a shallow depth of field have a very limited range of focal sharpness. In an image with a shallow depth of field the front of a bird could be sharply in focus while the back of the bird is out of focus.

Digital zoom: The use of electronic manipulation by a digital camera to create the impression of a larger image. The quality of the image degrades rapidly as the amount of digital zoom is increased.

Eyepiece: The lens that is closest to the eye when someone looks through a spotting scope. In some cases the eyepiece is a fixed component of the scope and in other designs the eyepiece is a separate item that can be changed to meet specific magnification needs. The eyepiece plays a large role in determining the overall magnification of the spotting scope.

Exit pupil: An indication of the light gathering capability of a lens, such as in a spotting scope or binoculars.

Film speed: Digital cameras do not have film, of course, but many have settings that roughly correspond to an equivalent film speed setting. Having a digital camera with the capability of selecting different "speeds" is like having a camera with several different rolls of film from which the user can select.

Settings of 50, 100, and 200 are often used. Digiscopers should experiment with their own combination of scope and camera to determine the best selection.

Magnification: An indication of how many times closer an object appears when viewed through spotting scope or binocular. Objects viewed through a 20x spotting scope appear 20 times closer than they actually are.

Megapixels: An indication of the amount of image information that can be captured by a digital camera. To oversimplify, the higher the megapixel rating the higher the overall image quality. There are many other factors that affect image quality, with lens quality near the top.

Objective lens: The large lens (the one farthest from your eye) at the end of the spotting scope. The larger the diameter of the objective lens the greater the light gathering capacity, and in general, the brighter and sharper appearing the image.

Optical zoom: Using manipulation of a lens system to provide increased or decreased magnification. Optical zoom maintains a higher image quality than digital zoom.

Photoshop: A software package by Adobe that is widely used by digiscopers for cropping and manipulating images.

Shutter speed: An indication of how quickly the shutter of the camera opens and closes. Slow shutter speeds are used in low-light conditions and faster shutter speeds are used in bright conditions.

In automatic mode many cameras will adjust the shutter speed automatically. When attached to a spotting scope it may be beneficial to adjust the shutter speed manually.

Vignetting: An unintended (usually) darkening of image corners in a photographic image.