BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="typo" data-source="post: 3495841" data-attributes="member: 83808">Bob,I've only managed to try the HGL a couple of times but I found it a very likable binocular. I try not to comment on brightness perception as it doesn't seem to have much to do with peak transmission, but at the time I remember a FL and ELSV appeared brighter, and so did the EDG. However, I do know appearances can change markedly with the illuminating light.Reflectance obviously varies with the wavelength but also with the angle of incidence. Maximum daylight visual sensitivity is around 550nm. Looking at multiple spectra for protected silver mirrors at different angles, reflectance is typically at 95 to 96%. Dielectric mirror coatings vary enormously in quality, but can exceed 99.5% for specific wavelengths (and angles). In a high quality binocular transmission at 550nm would be around 4% lower for silver than dielectric. The best SP models would be around 93% which would put the potential maximum for silver at 89%. The difference between silver and dielectric may be a little less in the red but much larger in the blue.Arek has said his older plots should only be viewed for relative transmittance, not absolute value but it's worth pointing out that his comparatively recent data for the silver prismed Endeavour ED II x42s were both under 85% at 550nm.David</blockquote>