Originally posted by Caat There are several issues with this idea:
1). You've already mentioned this: placing restrictions on the maximum diameter of the rear, and possibly middle, elements.
Yeah, so that means that we wouldn't have non-retrofocus 35mm/f1.2 lenses...
The advantage of having elements close to the sensor is for making wide angle lenses with non-retrofocus compatc design. If we are ready to through out compactness for large aperture, then retrofocus would just do it right.
To me this issue is non signifcant for the concept, which is about adding compactness to the
system.
Originally posted by Caat 2). The mount would only be compatible with K mount lenses - you couldn't adapt other brands because the registration distance would be the same as a K-mount.
Whilst you are mainting backwards compatibility with existing K-mount lenses by keeping the same registration distance you are effectively binding the new lenses to a 40 year-old mount. This is OK if you are going to continue to produce DSLRs and therefore K-AF lenses but if Pentax stops making them then the USP of their new K mount is no longer relevant (except from a legacy users perspective). The system with a new lens attached is only going to be slightly shorter front to back than with an original K mount lens attached.
You're comprimising the mount purely for backwards compatibility. I'm not convinced this is a good idea.
I say comprimising the mount because new lenses for the mount are bound to be more complicated to design. This added complexity brings no inherent benefit to the lens itself.
To my mind Pentax either have to stick with the K-AF mount as is, remove the mirror and work on shrinking all other parts of the system (bar the registration distance) OR develop a brand new mount. In my opinion the latter is the most sensible and viable option.
There are already Next and m4/3 camera for the purpose of adpating every mount. And the new Next 7 seems like the perfect camera to do the job.
With an evolved K-mount, you can still use M42 and K lenses, which makes already a very broad choice in weirdo lenses.
Oh and by the way, the F mount is 54 year old, have seen the introduction of electronics, 2 versions of AF and different sensor formats, and Nikon users seem quite happy with it.
The K-mount have shown as well as much versatility, the MX have shown that making compact is not a problem with the mount, but with all the gitzmos around, AF motor, sensors, LCD screens, CPUs, batteries... All of those will eventually become much more compact shrinking the camera around the image sensor.