I read the page in question. It's extremely vague about how information is communicated, just that it is, the obvious answer of a combination of mechanical and electronic communication (Which is known to be implemented on another extremely similar mount) is the one which shaves with Occam's Razor. I don't think its working the way you seem to think it is. And until someone who has actually disassembled an F or FA lens tells me I'm wrong, I'm not going to take a 1 line cite at more than merely face value.
While I suspect Pentax could implement what you suggest, I also suspect that it would require an update of the lens communication protocol and would not be backwards compatible. Also in-body aperture control is distinctly more fine-grained than the aperture control on the lens, from a general use standpoint, given the standard 1/3 stop control from the body and the normal 1 stop control from the lens (Yes, you can set it in-between the click-stops, and that is infinitely variable. I do this myeself on occasion. This is one reason why there is likely no encoder on the aperture ring, as the aperture simulator is better equipped to handle infinitely variable apertures, being an inherently analog device). Also, if you are correct, why the heck does Pentax not already use this info for more than just aperture display on older models? -Adam P. J. Alling wrote: > Like I said read the page. It tells all and you'll be closer to the > truth, and not nearly so annoying. > > We're talking about a mechanical system here. You're assuming that the > lever in the camera and the mechanical linkage to the aperture mechanism > in the lens is more accurate than the marked aperture on the lens. If > they are not in perfect agreement, I'd bet on the lens first. > > However you've completely missed the point. If Pentax implemented an > entirely electronic aperture ring on future DFA lenses it would be > trivial to use the system currently implemented in the F/FA lens spec. > This would allow the DFA lenses to have an aperture ring at very little > additional cost. It would of course let the those using F and FA lenses > use the aperture lens if they wanted to. > > Adam Maas wrote: > > >>Perhaps the same way as the Nikon's do with an AF lens and the aperture >>not at minimum? Relative aperture based on the aperture simulator and a >>little math from the max aperture info given by the lens to the camera. >>I'm seriously doubting that there is an electronic encoder added to the >>aperture ring, unless someone who has disassembled one feels like >>telling me differently. Electronic communication of exact max aperture >>at the current zoom length would be required to make the display work >>correctly with variable-aperture zooms, which is likely why it doesn't >>work with A lenses which lack datalink capability. >> >>Note that even if there is an aperture encoder in the lens, your idea >>may not work for mechanical reasons. taking the lens off of A will >>mechanically limit the minimum aperture the lens can be set to. While I >>can see a way around it (If you're taking the setting from the lens you >>won't want to drop the aperture any smaller in the first place) I can >>also see this being an issue, especially with variable aperture zooms >>(Do you take the absolute aperture set and give up minimum aperture at >>all but the widest focal length? does the ring only give relative >>aperture like it would on an older body?) >> >>-Adam >> >> -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
