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Message: <blockquote data-quote="ksbird/foxranch" data-source="post: 1301071" data-attributes="member: 37413">Even from these rather simplified presentations it becomes clear that since there are an infinite number of variations in the refractive index of any medium (ie. glass) depending on the frequency of the light reflecting or refracting with it interactively, then all phase compensation coatings used in roof prisms are only rough approximations. Even if the number of approximations is increased to 60 or 100 or 1000 approximations across the frequency bandpass of light passing through the objective lens of an optical device, the phase corrections for the s and p light polarization problem is at best an approximation and would have to create more visual distortion that a porro prism system using surfaces exactly perpendicular to the lightpath direction.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?There are places like Russia where the stampede to make and sell roof prism binoculars is much reduced because sophisticated purchasers can see that AT ANY Price, the porro prism model of an 8x42 for example, will outperform the roof prism version. It wasn't that difficult for Nikon to make their SE series (or Fujinon with the FMT series) as the easy choice for "Best visually" at each magnification level. If Pentax decided to make an ED version of the 7x50 DCF II WP they would likely be in this upper stratosphere optically as well, and they would be making a center focus, waterproof binocular with aspherical eyepieces that would likely be better than every 7x50 roof prism binocular in any comparable way. I'm not sure why Zeiss doesn't make a waterproof internal focus version of the 7x50 Marine (anything Pentax can make I'm sure Zeiss can make), or why Swaro doesn't update their Habicht line, including models with ED or flourite lenses and high end coatings. Leica is committed to roofers at all costs, so that explains that and Minox doesn't want their expensive bins (now all roofers) with aspherical lenses to be compared to Nikon, Olympus or Pentax porros with aspherical lenses should Minox enter the porro market with a serious high end product. But until some company comes up with an infinite number of phase correction coatings for their roofer, it won't be as good as the porro they could have made with the same eyepieces and objectives.</blockquote>

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