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="Surveyor" data-source="post: 1224134" data-attributes="member: 50720">Ron;I do not believe you are crazy. Over the last few years of testing transmission values I have developed some opinions that are probably not shared by many.I have been in contact with Leica, Zeiss, Swarovski and Nikon trying to get information on test parameters and have been told that they do not publish that information because it is too easy to be taken out of context and that no one range will give a complete picture and will just wind up with people like me just comparing numbers instead of the overall image quality, which is hard to quantify. I have also discussed on occasion with some of the more informed members of the forum but with no consensus. The only maker who supplied any information at all was Leica, and they did supply me with comparative transmission curves for the 10x42 Trinovid and Ultravid (non HD) to compare to my measurements and indicated that I may “be on the right track”.Anyway, and this is strictly my own personal opinion, is that the photopic region of the transmission curve (500-600 nm) may control the apparent or perceived brightness, that the overall band-pass (370-780 nm) may improve the contrast and that the peak transmission and the overall shape of the band-pass response may set the color temperature of the overall curve and set the color bias for average viewing and there are probably many more interactions that I have not even considered. If this is indeed the case, you can see why your Trinovid, while appearing dimmer (5% at 550 nm) than others may well have better contrast and a more pleasing texture (color temp. and bias), within about 2% (370-780 nm) of the Ultravid. It is my personal opinion that contrast has as much, or more, impact on the low light performance of a binocular as the overall brightness does.I concur with Henry’s first paragraph and add the following thoughts. Most consumer optics these days have blocked the UV portion, starts steeply declining at about 450 nm and the IR range, starting around 780 nm is non visual. I have read somewhere, though can not find it again, that IR light increases the gray/black range, while the UV light increases white range. I know that the eyes are more sensitive to UV, even down to around 300 nm, than the photopic curves would indicate. I am also familiar with very high temperature, diffuse blue/white light (7000-12,000K) being very bright, but at the same time, detracting from resolution. I am attaching some images, one is a list of bino’s that I have good information on bandpass and color information for and two Leica curves for comparison.Ron</blockquote>

Verification