If only it was that easy. You could fool the camera by turning a K mount into a pseudo KA mount, and it would appear to work, inasmuch as it would go through the motions.
The fly in your ointment is that between the K/M mount and the KA mount, Pentax changed the stopdown lever from a non-linear action to a linear action. This was so that in program AE or shutter priority AE the camera could control the aperture setting by moving the stopdown lever by an amount that corresponded to the chosen aperture, e.g. wide open = no deflection, minimum aperture = 100% deflection, stopped halfway down = 50% deflection (my figures are assumed for the purpose of illustration, the true deflections could be different). The same lever on K/M mount cameras and lenses was only intended to deflect fully, the aperture would be constrained to the value set on the aperture ring. Partway deflections wouldn't set the lens's diaphragm to any predictable value, and different lenses would respond with different degrees of stopping down for the same deflection of the lever. That's not to say that spoofing a KA mount has no purpose. It would permit use of the lens in meterless manual, and perhaps (I'm not certain) in stopdown metering mode. Without the modification the lens wouldn't stop down at all, it would be at full aperture at all times. regards, Anthony Farr ----- Original Message ----- From: <[EMAIL PROTECTED]> > Wouldn't it provide a practical solution to the ist situation? > If the body believes an "A" lens is attached then it could > control the aperture with the built-in facilities. > Is that not correct? > > Collin >
