Canon’s implementation on the great whites uses a ring, a switch, and the IS stop button. I use it in some situations with my 600/4.
Agree it would be handy on the 100-500 as well, but while a single-button implementation would be possible it would differ from the superteles and that would not be ideal, IMO.
Since the 100-500 is ‘affordable’ (relative to the great whites) perhaps adding the regular focus preeet hardware would have added too much to the cost.
Yes, it would cost a bit more to manufacture, especially if implemented as on the big whites, but possibly that would be compensated by additional sales, and hence only a minor increase in cost to the consumer.
I think I'm correct (haven't checked) in stating that Sony, Nikon, Tamron and Sigma all have custom buttons on several of their lenses, which cost far less than the 100-500, so I do feel that Canon have let themselves and their customers down by excluding it. I could sure make good use of a custom button if they provided one.
I assume a single button implementation could work by focusing at the required distance, double-tapping the button to lock it into the memory, and that the lens could be refocused again by holding down the button for the duration of the shot? I have no idea how it's implemented on Sony, Nikon, Tamron and Sigma lenses.
Edit: Actually, come to think of it, it could even be possible (although it won't happen) to preset a focus point via a firmware upgrade that allowed the function to be assigned to a back button on the camera, as the distance data is already transmitted from RF lenses to the camera....
) it's only the hugely expensive big white primes that have this function. It really surprised me that Canon didn't put one on the 100-500mm...
www.the-digital-picture.com
