Hi, Just a quick note to share that - the older chrome Seikosha 150mm Mamiya-Sekor lens at least - covers 4x5" nicely. I managed to put it onto a Toyo/Linhof board without too much hassle, see pic.
I had bought it mint on a damaged/disassembled focus mount, cheap, for parts. Not thinking much of it, I nevertheless thought I'll try it on my 5x7" to check what the image circle might be.
I had to cut the end-plate off the (already damaged) helix and then screw that onto a (Copal #1(!)-sized) board, then remount the lens. The Seikosha-S shutter is not standard Copal #0 in all respects, but has that custom, built-in preview and cable relase mechanism subassembly, making the Copal 1 board easier to use, to allow for recessed retaining-ring access.
Anyway.... It turned out that good image circle is in excess of 170mm wide open, making it very similar in capability e.g. to the Schneider Xenar and thus fine to use for 4x5" with modest movements. Images have a lovely look with excellent contrast handling; filter thread is 40.5mm and the coating and color rendering look about the same as on one of my other Tessar-type favourites, the Komura-Commercial 210mm, f/6.3. Normally not that prone to gear-adulation, I nevertheless think that it is quite a lovely lens; a keeper for now.
That's all, folks!
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