On Oct 4, 2010, at 21:54 , Joseph McAllister wrote:
Well PDML'rs, you forced me to break out my DA* 50-135 ƒ2.8 today. I
hadn't used it since I tested it when I bought it almost two years
ago, at least as far as I can recall. I used the DA* 16-50 ƒ2.8 and
the DA* 60-250 ƒ4.0 for all my canine action shooting. The 16-50
only occasionally.
So I hooked it up to the K-7 figuring after all, it's getting dark
earlier, the AF could use the extra stop & a half. Focused on a few
things around the house. Zip zip. No focus problems. Batteries
charged a few days ago still good. Packed it up and headed off to a
sunny late afternoon of shooting.
Got to the park, set up, (that means sitting on a bench and turning
the camera around to shoot as I carry it upside down on it's strap
so it doesn't bang into doorways and nearby walls) and start
shooting. Couple of shots of dogs playing 5 feet away from me, zip
zip - sharp focus. Took another shot about 25 feet away — that
didn't look so sharp… Another about 6 feet away — ok - that looked
sharp didn't it? Woah. Now there's a pooch running and coming at
me… Nothing.
Removed and reset lens on body with power off. Power on. Prefocused
lens so it could follow action. Nothing. Went through everything I
could think of, moving switches on camera body and lens that would
affect focusing. Nada. By the time I got home the batteries were
indicating half charge, both of them. Mounted the DA* 16-50 ƒ2.8 to
see if low voltage was the problem. Nope - it focused fine, and
fast, even in room light after dark. So does the DA* 60-250 ƒ4.0.
I'll finish this paragraph after both batteries are charged. I know
one should do, but if it's sticky, the amps of two might free it.
This could take all night -
After inserting a freshly charged NiMH battery in the body alone
(couldn't wait), I mounted the DA* 50-135 ƒ2.8 and turned 'er on.
Nada. Messed with the switches again. Nada. Ran the focus back and
forth manually from end to end, taking care not to slam into the
"stops" that I guess are physical limits of some kind. After a dozen
tries going from manual focus to SDM, the darn thing started working,
and continued to do so until I got bored and watched TV some more.
This is similar to what I recall having to do at times to get the DA*
16-50 ƒ2.8 to do it's SDM thing.
I think I will let this slide for now, even though it is a crappy
system that makes these kinds of side-show shenanigans (worked that
into a sentence) with Pentax's top of the line DA optics.
I'm sure they are working on it and all will be well in the world
again soon.
I wonder if the electrical energy to move these circular disks/plates
is shaped in the camera body or the lens itself. If Pentax comes out
with this new-fangled "DC" focus drives, then I would think the body
will have to ascertain the lens's needs and supply it through those
two contacts or… or… or… turning the drive shaft ! That makes me
wonder if the polarity of the supply is reversed in the body
controlled by the FAFOX system, or just supplied and letting the
lens's circuits determine the polarity in situ based on data from SAFOX.
I think about these things too much!
Joseph McAllister
pentax...@mac.com
http://gallery.me.com/jomac
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