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06-05-2011, 04:36 AM   #1
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KAF pin contacts diagram / guide

Can anyone point me to a diagram or guide which explains and identifies the role and function of each of the KAF contacts / pins, please? I've tried searching but have only found the photos of the Pentax lens mounts, unfortunately the individual contacts are not specifically identified. I want to try covering up one or two in order to exploit the trap focus or catch in focus of my K-5 and either my DA 18-135 WR or my D-FA 100 macro WR lenses (yup, need to be out even if it rains). The combo won't catch in focus as it is. The user guide (and other threads here) tell me I need a manual lens (or a DA* with on-lens MF switch), none of this fancy new stuff (smile), *or* I need to get to work with a little Scotch tape to cover-up the relevant contacts. Don't want to attack 'em at random (grin)... Many thanks!

06-05-2011, 04:46 AM   #2
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The best source for this info is the K mount pages by Bojidar Dimitrov. Try starting here K-Mount Evolution, Features and Operation and follow different links depending on which version of the mount that you are working on.
06-05-2011, 08:37 AM   #3
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Sorry lester11, can't help with the info you're after, but wondered what the issue is?
06-05-2011, 08:51 AM   #4
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QuoteOriginally posted by Douglas_of_Sweden Quote
The best source for this info is the K mount pages by Bojidar Dimitrov.
Hi Douglas, thanks for the link. Some contacts are indeed identified on the different Bojidar pages, but there seems to be no overall synthesis in one place, and not every one of the contacts are explained or mentioned as far as I can see. I'll probably have to make my own diagram!

06-05-2011, 08:58 AM   #5
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QuoteOriginally posted by JohnX Quote
Sorry lester11, can't help with the info you're after, but wondered what the issue is?

Hi John. My system won't "catch in focus" (p. 134 of the K-5 user guide) since neither of my two lenses are manual focus or are lenses with a MFsetting on the lens. Some threads on this site tell me I can cover up a contact or two to get "catch in focus" with my auto-focus-only DAs, and I'm wanting to find out what contact(s) they are...
06-05-2011, 05:19 PM   #6
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Hi Lester,

You'll probably be surprised by the function of most of the contacts since they do nothing more than communicate the min and max apertures of the lens, but it's pretty well spelled out this page:

http://www.robertstech.com/matrix.htm

B Dimitrov has the same info on his site, but it's hard to find the page -- I stumbled upon it once, and cannot find it again. . .

What you have to do to allow Focus Trap (CIF) with AF lenses is to short the "Data" pin with conductive material -- most use Aluminum foil, but some use metal tape. The Data pin is only used by AF lenses, so shorting it tells the camera body that there is no pin there, and that must indicate a MF lens. This obviously not harmful to the camera since a K, M or A series lens would have bare metal of the mount there, which shorts the pin.

Scott
06-06-2011, 02:41 AM   #7
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Hi Scott, thanks for the link and explanation, I'm a computer engineer some of the time (smile) and so that is *exactly* what I was hoping to find.
06-06-2011, 03:19 AM   #8
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All the same info and some more are on the Diminitrov link I provided if you just follow the links for the KA, KAF, and KAF2 mounts. As others said, 6 of the pins are just a binary way to communicate the min and max apperture. Cameras can be tricked if you change how they are insulated or not. But if you modify an K or M lens with the right set of pins to make it look like an A lens to the camera, you still don't get correct exposure becuse they changed the mechanical apperture transfer from logarithmic to linear when they changed to the KA mount. Something Robert forgot to tell you, but you will notice it if you start doing your own modifications.

06-06-2011, 05:28 AM   #9
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Hi Douglas. There are two lenses I want to use with the K-5, the DA 18-135mm F3.5-5.6 WR and the DFA 100mm F2.8 Macro WR. I guess I want them to look like a M lens to the camera, not an A lens. If I short out the 'data' contact, presumably your comment about incorrect exposure because of a change in aperture transfer does not apply? Thanks!

As I mentioned, the Diminitrov pages are indeed useful, but there seems to be no overall synthesis in one place, not every one of the contacts are explained or mentioned as far as I can see, and one or two pages seem to contradict the information in other pages.
06-06-2011, 05:35 AM   #10
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see this link

it explains the exact coding of the aperture pins

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/117613-convert...ml#post1216725

ther eis a 7th pin, not addressed in the post which was added with the KAF mount, for the AF data and communications, it is the farthest away from the lens locking pin
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