The distinction between birding and bird watching is probably best described as one of 'passion'.
The birder has an over-riding passion for their subject and as such, is likely to got to greater lengths, and expense, to ensure they have absolutely the best birding binoculars they are able to afford.
Birding enthusiasts often specialize in one type of bird, and know all their plumage variations, together with all the habitats they are likely to frequent. They will often travel large distances to view the object of their 'passion'.
Birding takes place most frequently in temperate climates, when the birds are in migratory mode, during the spring and autumn. Birds are easiest to spot in the early morning when searching for food. Early mornings have low light levels.
The specification of birding binoculars therefore, needs to allow for this low level of light, by permitting the greatest transmission of light possible, through the optical path of the instrument.
Such are the advances in optical coating technology over the last five years that it is now possible to reduce the loss of transmission to less than 3%. In other words, a transmission percentage of 97% is possible, with the coating technology available today. This results in the brightest image possible under all lighting conditions, an absolute 'must have', for any serious birder.
Of equal and possibly even greater importance to the birder is the ability to identify the colors of the plumage of the bird they are observing and the variegations thereof. To this end, the binocular must transmit colors without aberration, a difficult proposition, in a light path that consists of two lenses and two prisms as a minimum.. Once again optical coatings come to the rescue and can reduce chromatic aberrations inherent in all lenses and prisms to levels, where natural colors and the contrasts between these colors, is clearly identifiable.
So what is the best specification for birding binoculars?
The commonly agreed criteria are an 8x magnification with a 40mm or 42mm diameter objective lens.( the big one at the front of the binocular.) This provides the best combination of magnification, field of view, depth of field and light transmittance. The optics all need to be multi-coated, to minimise reflections, and maximise color transmission and contrast.
This specification can often add up to a significant purchase price. To the serious birder, the cost of the best birding binoculars is considered money well spent. >