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This directly contradicts information on the TeleVue website, information elsewhere on the web regarding coma, and what Al Nagler himself told me directly.
All f/4 instruments have exactly the same angle to their lateral rays, regardless of focal length. So it is not related to focal length, but focal ratio.
Al told me directly he designed the Paracorr for a focal ratio of f/4.5, but that it works better on longer f/ratios. At some length of f/ratio, the Paracorr would be applying reverse coma, but it is above f/8 and no one will be using one above that f/ratio. So it IS f/ratio, not focal length.
Your statement regarding magnification also directly contradicts what you see (but not because you're technically wrong). All my eyepieces have 82 degree fields, yet coma is far more visible in the lower powers. Why? Because the coma in the edge-of-field star image is considerably fainter in the more magnified image. This is why the edge of field stars in a low power 50 degree eyepiece appear to exhibit more coma than a very high power 82 degree field of view. Technically, the comatic star image is the same size, but in practice you can't see it.
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