Originally posted by kivis Ugh crew1 say enable and others say disable. Yechs!! Help!
It's not really that complicated, and it's also rare for it to matter.
With a lens without shutter it doesn't matter what you set, you will use the electronic shutter anyway.
With a lens with a shutter, you will always use that shutter if you use a time that the shutter is capable of performing. (1/2000 or longer for the native lenses, 1/1000 or longer for the Pentax K adapter.)
If you set it to disable and use a lens with a shutter, you will not be able to select a time that the shutter cannot do. If you set it to enable, you can, and will then (and only then) use the electronic shutter.
The selection is between being sure you use the lens shutter ("disable"), or being able to select shorter exposure times that risk the jello effect (but usually it's no problem).