Spotting scope parts and terminology

Spotting Scope Parts

Zoom Eyepiece - Can be adjusted from low to high zoom to change the amount of magnification of the image seen.

Armoured Body - Rubber coated body to offer extra protection against knocks and general wear.

Tripod Adapter - Fitted with a threaded hole to accept common tripod fittings (1/4-20 UNC thread).  Many tripod adapters can be rotated using the side-screw, allowing the user to view with the eyepiece on the side.

Objective Lens - Light gathering element of the spotting scope.  Larger objective lenses have a better light gathering ability and produce better, brighter images.

Sunshade - Extendable to prevent unwanted glare on the objective lens.

Focus Adjuster- Available in two styles:

  1. Focus Knob - Rotates to adjust the focus distance.  Some spotting scopes feature a dual focus knob for coarse and fine adjustment speeds.
  2. Barrel Focus Wheel - Rotates to adjust the focus distance.  Offers quick, easy adjustment with lots of feedback for a more controlled feeling.

Terminology & Phrases

Field Of View (F.O.V.) - The width of the spotting scope's view.  This can be measured in terms of angle (degrees), or by a set distance. e.g. the F.O.V. of the Sapphire ED Spotting Scope is 35m wide when looking at an image 1000m away on lowest magnification and 21m wide at an image 1000m away when on highest magnification.  This is also equivalent to 105ft and 63ft respectively when looking at an image 1000yds away.

Eye Relief - The correct distance for the pupil to be located from the eyepiece lens.  When at this distance the best viewing experience will be obtained.

Exit Pupil - The diameter of the viewing image when the eye is positioned at the correct eye relief.  This is calculated by dividing the objective lens diameter by the eyepiece magnification. e.g. for an 80mm objective lens with an eyepiece set at 20x zoom, we divide the 80 by 10 to get 4mm.

Close Focus - The closest possible distance that the spotting scope can be focused at.

Fully Multi-Coated (FMC) - Means that all lenses and glass surfaces have a coating layer. Multi-coated means that at least one of the major optical elements in the binocular has a coating.

Extra-Low Dispersion (ED) - ED glass is a different type of manufacturing process designed to remove chromatic aberration (colour fringing).

Phase Corrected (PC) - like ED glass, PC glass works to stop chromatic aberration, but is lower cost and not as effective as ED.

Digi-scoping - Digital cameras can be attached to the spotting scope and used to capture photos through the spotting scope's optics.