Trevor's Spotting Scope and Optics Review

This is a good scope for beginners in astronomy. It is made of aluminium, and is strongly made and tough. It has an 80mm air-spaced doublet objective lens, which helps to reduce but not eliminate Chromatic Aberration (CA). It also comes with a 6x30 finder-scope which produces upside down images in the eyepiece. The scope is supplied with a 1.25 inch erect image diagonal/prism. It is supplied with two eyepieces of 10mm and 25 mm focal length respectively. The eyepieces get you started but really need to be replaced with something better  if you start to get serious about observing. You also get a Barlow lens which is used to double the magnification. The scope is then capable of magnifying astronomical and terrestrial subjects by 16 x, 32, 40x and 80 x. The telescope is designed for astronomy but can be used as a terrestrial spotting scope.   I tested it on the Moon and the planets of Jupiter and Saturn and the Orion nebula. The Moon produced a very bright and clear image ...

 Many  budget spotting scopes and binoculars do not use extra low dispersion (ED) glass which helps to reduce Chromatic Aberration (CA) to a minimum. Intense CA can ruin the view through your glasses as it causes purple and green fringes around the subjects being viewed. It is caused by the objective lens not being able to focus all the wavelengths of light to a single point. CA is especially apparent when viewing very bright and high contrast subjects, such as the Moon, against a dark sky. With a spotting scope it is apparent when observing a bird sat amongst tree branches in very bright and high contrast situations. The tree branches often form a matrix of branches which are sometimes in focus and sometimes not. CA will appear as purple fringing around the branches or even the bird in focus.  It is possible to reduce or completely eliminate CA  by using triplets, which use three lenses combined to focus blue, green and red to a single focal point, or doublets, whic...