On Wed, 07 May 2008 11:51:47 -0400, P. J. Alling wrote: >James wrote: >> Very well put. >> But please explain why every AF sigma lens I have doesn't show the correct >> apature range on my super A. despite haveing some A contacts. >> >It's Sigma.
cannot argue there. I have an older sigma AF lens that works ok on my MZ7 but won't at all on my K10D and MZ60 and the super A gives Apature readings outside the range the lens has. So now it is a single camera use lens. >> Also why does the MZ60 have only 2 contacts missing when it was never >> designed to use A lenses at all. >> >It's just possible that some "A" information is necessary for the >Digital protocol to work and the MZ60 reads what it needs to. Ya think? personally. No. >> Why does the sigma lens when I pulled it apart have all contacts except for >> the * go via a flexiable circuit trace to a board in the lens when all that >> is required of A contacts is to be shorted or open? >> >Sigma probably thought it could control which contact was open or >shorted dynamically and fool the camera electronics. Which being Sigma >they failed miserably at. (Here I'm guessing the first part but I'm >sure about the second). Tracing the circuit in the lens is very hard and for my older eyes, twice as much. Couldn't get very far with this part. >> If what you say is true, then the MZ60 should only have the digital pin >> which it doesn't. >> >No, because the digital protocol builds on the A protocol, it needs the >information conveyed by the "r" pins, why that choice was made I don't >know, but I'm not guessing, I'm thinking. I also think the R pins are used for digital comunations as well. It is very easy to add extra functions to pins on both sides (camera and lens) for the F protocal while retaining backward compatiability. (except for sigma) Incendently. My DA*16-50 lens has an extra full contact on it's metal mount compared to all other lenses I have. Looks like Pentax have added an extra function to one of the 'm' pins. maybe for SDM. >Sorry, it's just bad design. If Pentax was going to double up on a >pin's functionality it wouldn't have instituted a separate digital >contact. There were plenty of "A" pins already. Pentax made good >design decisions up till now, I don't expect them to stop. Maybe Pentax added the extra one for some engineering reason. Also depends on what type of serial protocal they used >> When I alerted Boz to the very limited MZ60, even he asked what do the other >> contacts do >> >Maybe Boz was simply telling you to go pound sand. He also asked the same of someone else, I can only assume some guy who has provided some tech info for boz >> so far, noone can answer. >> >Since the MZ60 is only interested in the maximum aperture, (check the >chart on the Ka page on Boz's site I'll leave it to you to figure out >what the "r" pins and the "m" pins convey, the pattern isn't hard to >figure out), I can assume that the digital protocol tells the camera >all it needs to know about the minimum aperture and the "m" are >superfluous, I say that because it works perfectly well without them. . Ithink all pins are used in some form of digital protocol. why get only one aperture value digitally when all of it can be done at the same time. I have tried to measure what is happening with my digital multi meter set to logic level. ie logic probe. All I got from all pins was pulsing. ie all went high low high low very quickly. none were stuck high or low Even the digital pin which I think is power. maybe pentax only powers the lens when the camera wants info from the lens thus saving battery power ? If I had a 10 input logic analyser, I would be able to say for sure what is happening. James -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
