Thank you everyone for your contributions to what has been for me an interesting and informative discussion.
Some of my angst around Canon not making a mirrorless EF mount back is that it seems they have given up on trying to improve dynamic range, and have instead chosen to reignite the megapixel wars.
Another substantial portion is similar to what rickztahone mentioned:
...as an A-mount shooter, Sony a99, I feel left out that Sony has basically abandoned the mount and gone over to the FE mount.
Don't get me wrong, I really like what they are doing with the FE mount, I especially want the A7rii for the dynamic range, but my pro gear is A-mount and Sony seems to have forgotten us.
rickztahone, in case you haven't heard, it seems to be official now: Sony has no plans for additional full frame A mount cameras. See
this article
Boy, that seems harsh to me, but as others have mentioned, Sony is not big on coddling its customers.
While perusing their website, I came across this page which provided me with what may be some insight into their decision:
Sony lens basics Here's the key quote:
"...the main difference between A-mount and E-mount lenses is their “flange back distance.” The flange back distance is the distance from the rear of the lens to the image (sensor) plane. Since many A-mount cameras are traditional SLR designs that have a reflex mirror between the rear of the lens and the sensor, they need to have a flange back distance that allows space for the mirror. E-mount cameras, on the other hand, do not have reflex mirrors and therefore can be designed with a much shorter flange back distance, and consequently smaller lenses overall."
Sony historically has been big on small and portable. Remember the WalkMan? Because of the need for a more significant flange back distance, a mirrorless A mount camera would always be chubby compared to the current E mount backs. Like twice as fat / thick. I think the desire for the smaller form factor is what motivated Sony to call a halt to further A mount backs.
I am concerned that Canon is making a similar choice. The inherent design of a single lens reflex camera, digital or analog, requires the heftier flange back distance from lens to sensor than does a mirrorless.
What is especially difficult for me to reconcile is that Canon, having produced over
110 MILLION EF lenses (
Canon celebrates 110,000,000th EF lens), would leave those proud lens owners hanging.
Personally, I could live with a back that was the same width of my current dslrs if it were mirrorless and fit my existing EF lenses without any adapters.
Quoting rickztahone one last time: "[/rant]"