Photography and the Spotting Scope
Most spotting scopes have an optional camera adapter that lets them be used as a
telephoto lens for high magnification photography. However, just how well
they work for photography depends on the type of scope.
Many prismatic spotting scopes can only be used for photography
if an eyepiece is used as a transfer lens between the scope and the camera to project
the image back to the camera’s film plane.
When an eyepiece is used as a transfer lens, the focal length
and focal ratio of the scope increase dramatically. This makes it difficult to focus
in any but the very brightest of light conditions, as the image on the camera’s
focusing screen becomes dim indeed at the scope’s f/15 to f/60 focal ratio. Since
an eyepiece is designed to form a circular image, there is usually some vignetting
(or dimming of the image) at the corners of a rectangular photographic negative.
Also, the extra lens elements in the eyepiece lower photographic contrast and resolution.
In addition, minor vibrations – the camera mirror slapping
up during exposure, the shutter opening, even a light breeze shaking the tripod
– are all magnified 15 to 80 times by the long photographic focal length, making
it difficult to take sharp and unblurred pictures.
Some scopes (catadioptrics; high end Leica, Kowa, Nikon,
Bausch & Lomb, and Swarovski prismatics; TeleVue refractors) do not use an eyepiece
as a transfer lens, so there are no non-photographic elements involved to lower
contrast and fuzz the image. While photographic magnification with these scopes
is typically not as high as it can be with a scope using an eyepiece in the camera
adapter, their shorter focal lengths and faster focal ratios usually result in sharper
If you plan to do extensive spotting scope photography, a sun shade for the scope
is strongly recommended if one is not already standard equipment.