Originally Posted by
Frank Petronio
It also matters if the shape of the blades are curved versus straight like modern Copals are, why they couldn't cut them with a curve is beyond me.... Modern Copals only have 5 blades -- as do cheap SLR lenses -- higher end SLR lenses have 7 or 9 blades, Leica and VC lenses usually have 9. If you look into a stopped down Leica lens they make a nice flower-shaped aperture hole. And Rolleis have rounder apertures than on the similar 80/2.8 Zeiss in a Hasselblad... which is why Rollei TLR shots usually a bit creamier.
Sometime in the 60s Synchro-Compurs went from 7 to 5 blades, so the earlier Linhof shuttered lenses can be found both ways... I think all the Copals have been 5 blades, as have been most of the post war American shutters. You simply have to look and ask before buying.
Of course you get perfectly round apertures if you shoot wide open. Oftentimes that's what I try to do. But if you try to shoot outdoors wide open you may want to find a shutter with a fast 1/400 or 1/500 speed, and/or some ND filters and use slower film.
I went through all this myself and currently use a later 5-bladed shutter because I want a nice, newer, reliable shutter (I really prefer Compurs) and I do try to shoot wide open when I think the background will benefit. But it is always a compromise... I doubt Copal will change their design at this late date, it is a pity they didn't care about such details but in the 1950s-60s when things changed over... I think the prevailing trend was to emphasize how darn sharp everything was over other lens qualities.
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