On Tue, Sep 24, 2013 at 10:19 PM, Godfrey DiGiorgi <[email protected]> wrote: > This should be qualified. Leica, just like Nikon and Pentax, deemed that it > was more important to maintain compatibility with their existing lens lines > than to redesign the lens mount on the M and F mount bodies, respectively. > However, neither M nor F mounts are ideal for 24x36mm digital sensors—they > can be made to work, but ideally a lens mount for a digital sensor should be > larger diameter relative to the format and a shorter registration distance, > to enable more flexibility in lens design for the digital capture medium. It might not be ideal, but they work pretty well; surprisingly, the M mount has more issues due to the small registration distance (requiring offset microlenses to compensate). > > Canon was roundly dissed when they obsoleted the FL/FD mount in the 1980s and > thereby obsoleted many owners' expensive lens collections. However, they were > prescient in developing the EOS mount which is huge diameter (about 51mm) and > a relatively short (44mm) register. The change has stood them in good stead > in the long term, although it cost them a lot of customers once upon a time. The large diameter should help at least in making large aperture lenses; but the registration distance is a mere mm and a half away from Pentax'. > > Olympus was unsuccessful in bringing out an auto-focus SLR lineup and had > pretty much left their pro system (OM) on the sidelines for years, delivering > a couple of new bodies and lenses only for the last decade of its production > history. When they started to think SLR with digital capture, they worked > with Kodak and developed the FourThirds mount, which has an even shorter > register than Canon EOS (38mm) and about the same outer diameter. This lens > mount is the only one in production that actually has the ideal sensor > size/diameter/register depth combination for digital capture SLRs and lenses > up to f/1.4 aperture settings. The Micro-FourThirds design is essentially the > same, scaling down the bayonet diameter along with the register depth to > maintain the same characteristics, and allowing for more compact body > designs—it was only made possible by the invention of high-resolution EVFs > and large sensors with Live View capability. Which is interesting, because unlike the "inadequate dinosaurs" (F and K) that mount it's now dead and buried - FourThirds lens owners being supposed to jump to the new mirrorless EM-1. I'm not aware of any Olympus FourThirds lens larger than f/2 - though Panasonic made a 25mm f/1.4.
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