That's pretty much how it happened. The "green button" technique was not only unknown at the time - it wasn't even available. In fact one of my posts shortly after that outing described what we had discovered, and even described a hypothetical change to the firmware that would make K/M lenses more usable (subject to the limitations of not having an aperture simulator coupling). When Pentax came up with the "green button" technique some time later it was practically identical to the solution I had proposed. (Not that I'm suggesting Pentax took the idea from my posting; all I'm saying is that they did the best that was possible.)
Shel & I experimented with several things with that K85 lens, including trying the technique Juan proposed. As the time we didn't manage to explain what was going on, and why stopping down the lens in Av mode seemed to produce OK exposures despite the fact that the manual claimed this would not be the case. It was only later, after examining the DOF in the images, that we hypothesized that the (observed) stopping down of the lens during the exposure cycle occurred after the shutter had opened. A little further experimentation confirmed this hypothesis. On Thu, Jul 21, 2005 at 12:27:29PM -0700, Shel Belinkoff wrote: > Juan. > > When John first got his D, I drove down to take a look at it and brought a > couple of K-mount lenses. At that time John was still learning about the > camera, and, of course, I knew even less about it. I don't think the > "green button" technique was even known at that time. Anyway, we fiddled > about with some K's on the D, and (John, correct me if I'm wrong) got a > good exposure or two, and thought we'd found the solution. Of course, the > next few exposures weren't quite as good, to say the least and to be kind > to ourselves. > > Shel > > > > [Original Message] > > From: Juan Buhler > > > > Of course, John, you are right. Funny, somehow I managed to make > > myself believe it was working. > > > > I even shot some frames around today's pic in my photoblog in this mode: > > > > http://photoblog.jbuhler.com/index.php?showimage=179 > > (istD, K24/3.5) > > > > I suppose that they ended up being usable because I was not more than > > a stop away from full open anyway. > > > > It would only take a simple firmware change to make the camera work > > this way though... >
