I do most of my landscapes with a 4x5 Tachihara and a Schneider 210 and have lat ely been looking for a wider lens for closer quarters.(specifically Antelope Can yon). I thought about an older lens like the Ektar 127, and got some good advice from this group, but I don't like the idea of having just enough coverage without mov ements. So I am considering a used 90mm for that purpose. I have few questions that I can't seem to find answers for, and am hoping some o f you can enlighten me a bit. 1. How long has the Rodenstock (Grandagon?)90 been manufactured? Are they all mu lti-coated, or are there old single-coats lurking out there? 2. Can this lens be used successfully without an expensive center filter, or is the falloff too apparent? 3. Are there vignetting problems when using standard screw-in filters? and 4. as long as I'm on the topic, is this too wide for slot canyon work - should I think more like 150mm? Thanks in advance.