Originally posted by Knock I got a k10d yesterday and I've been testing it out. I prefer to use older pentax manual lenses. I put on my pentax A 50mm/2 and everything worked fine in both Av and M. Then I put on my pentax M42 adapter to test out my takumars. They also worked fine in Av and M, but I noticed that I was not getting the focus confirmation indication light (green hexagon) in the view finder. This only happened while using M42 lenses, The view finder in the k10d is much better than the K-x I've been using, so the focus on the k10d is easier to catch, but I still find myself waiting for the focus confirmation light. Has anyone had any similar troubles?
I've had better luck. When I use the plated brass m42 to k mount adapter on an m42 lens, it does give focus confirmation. If you are using a painted or anodized mount adapter, perhaps some electrical contacts are not conducting?? You do have to set the camera up a little, step 1 below.
Pentax K10D has good support for KA lenses if they are set to the A aperture position. You do get aperture indication, focus confirmation, PTTL flash, and so on.
However, if a lens is not in the A aperture position or does not have an A position (like, for example, M lenses, M42 lenses, extension rings, bellows, etc.), function is limited by camera firmware. You must follow these steps, and even then it's crippled.
1. First, set "Using Aperture Ring" to "Permitted", which you will find in the C Custom Setting Menu. The K10D won't work at all unless you do this.
2. Even if you set the "Permitted" option, you don't get all functions. If you set the exposure mode to any value other than Av or M, the camera will override your exposure mode to be Av, or if set to M, leave it at M. You don't get F stop display (shows only F--), nor automatic flash control, nor automatic setting of the focal length for Shake Reduction. You'll have no auto flash control, it's full on or off.
Refer to pages 208-210 of the K10D manual, which is online here:
http://c2b6d376b97bcc466063-5420c200a1f030d1394a9548df6eadbd.r5.cf2.rackcdn....402_manual.pdf
As you may know, Pentax made these restrictions in firmware. They say the restrictions are necessary because on Pre-A lenses, the aperture lever changed aperture opening differently than on A lenses. Essentially, on K and KM lenses the aperture motion was proportional to the diameter of the aperture, while on KA and later lenses motion was proportional to the aperture area. Thus on KA lenses, aperture steps were proportional to F stops, which is how we change aperture anyway.
A cynic might wonder if Pentax just wanted to sell newer lenses. Such a big fuss over one pin. But that's how it is.
Regardless of theory, you can make any pre-A lens pretend to be an A lens in at least two ways.
1. Modify the camera A pin to be always on by jamming foil under it. (At your own risk of course.) The camera will believe all lenses have A mounts.
2. Modify the lens to have a grounded contact at the A position. One way: Scrape or drill to bare metal and dab a bump of conductive epoxy at the A pin location, making sure the lens mount has some bare metal elsewhere for ground to the camera lens mount. (At your own risk of course :-)
If you search the forum, you will find examples of past efforts to do those mods. You may be able to shoot, but exposure may be wrong, because the camera can't really accurately set the aperture opening. So you do get some features back, but not all.