On Aug 18, 2006, at 6:39 PM, Digital Image Studio wrote: > On 19/08/06, Godfrey DiGiorgi <[EMAIL PROTECTED]> wrote: > >> A lens without an aperture ring is less likely to break no matter >> what you choose to do with it: it has fewer parts to break. > > Huh? It just doesn't have an aperture ring, the aperture isn't set by > magic otherwise.
In a lens without an aperture ring, or in a lens with the aperture ring set to A, the lens opening is set by metered action of the camera's actuation lever on the lens' iris regulator lever. Using a lens with an aperture ring set to anything other than A means a) the communication contacts to the body are open circuit so there are commutators involved, b) the ring controls a limit stop for the mechanism internally, the camera actuator simply drops through to its minimum aperture setting and the iris regulator comes up against the limit stop set by the ring. There are detent fingers, little springs operating on notches in the mechanism, the A button and spring for it, the connection between the ring and the limit stop, etc. Yes, a lens without an aperture ring doesn't have an aperture ring ... and it doesn't have all the parts associated with the aperture ring either. It just has the iris regulator mechanism to interact with the camera actuator and a permanently connected set of contacts to communicate with the body. Thus the lens lacking an aperture ring is simpler and likely more robust on that basis. Godfrey -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
