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Message: <blockquote data-quote="ksbird/foxranch" data-source="post: 1301403" data-attributes="member: 37413">I guess I am unaware of the basis for the reference to company secrets in the post by ThoLa. I don't keep up with Swaro products, but a few of the other posters to this forum have commented that the Habicht series porros do not use the same coatings as the most current Swaro roofers.The argument ThoLa makes about other forms of distortions is covered where I say in my previous post that"Since all other factors are equal with porro prisms and roof prisms (ie. the cone shaped nature of the light beam accumulated and bent to reach the prisms, coatings for anti-reflection, fineness of polishing, quality of glass, eyepiece design etc.) ANY porro prism binocular made with the same materials and care as a similar roof prism binocular has to have better optical performance, because of zero phase distortion vs some phase distortion in any roofer made. Or am I misunderstanding Brewster and Fresnel?"Roofers have the same chromatic distortions etc. that porros have in all respects, and in addition roofers have an additional distortion that porros can't have, roof prism caused s & p phase distortion.Having worked 9 years as a trainer for Nikon and Mamiya camera products I can tell you that you are incorrect in your belief that simply correcting the phase for three color peaks in the wide color spectrum bandwidth will somehow correct for the infinitely variable amount of phase distortion created by an infinitely variable number of color frequencies creating an infinitely variable number of out of phase s & p waves due to the refractive index of most materials like glass having a variable index of refraction for every color frequency there is. On the product engineering side we have Zeiss touting the use of 60 layers of phase coating on their roof prisms which  allows them to space out the frequencies that they phase correct for, all along the wide color spectrum from violet to infrared.But since color films never had more than 4 color response materials, film making companies were always explaining that the recreated color images were always approximations (which is why the colors rejected by the multicoatings on one brand of camera lens could cause the color balance of the image produced to vary slightly from the color balance of the image produced by a difference camera lens (even by the same company) if it used different multicoatings). Approximation of the original image with some added phase distortion still remaining is about all phase correcting coatings do. They are producing REDUCED phase distortion in a few color frequencies in hopes of a better approximation of the original image by somewhat reducing the s & p color distortion caused by roof prisms themselves. The difference between the distortions in color fidelity caused by film (basically being non-linear in their response to various light frequencies) and roof prisms in binoculars (having added phase distortions) is that film produces more or less of a certain color in the original image, while roof prisms add phase distortions that reduce sharpness. With better phase correction approximations (like the 60 layer Zeiss phase correction roof prism coatings) you get a better Approximation of the original image, and with fewer phase correction coatings you get a rougher approximation of the original image. But with porro prism binoculars (all other parts of the light-throughpass system being the same) you don't get any phase distortions because these phase distortions are caused by a component (roof prisms) that porro prism binoculars don't use.</blockquote>

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