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Forum: Troubleshooting and Beginner Help
10-30-2018, 09:15 AM
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Thanks for the clarification. I remember reading that, but did not put the two together. :o
Steve
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Forum: Troubleshooting and Beginner Help
10-30-2018, 07:52 AM
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All but one of the contacts are legacy KA. Those are purely passive with binary state and are typically hard-wired and not controlled by the "chip".* They provide lens type ("A" vs. "non-A") and supported aperture settings. The two either side of the "A" contact encode the minimum aperture and the others (data contact excepted) encode the available number of aperture settings in half-stop increments. Maximum aperture is not explicitly encoded.
The contact pattern on the OP's mount is typical for an auto-focus K-mount lens. Note that the contact-encoded aperture information may be overriden by a poll for dynamic state through the data contact. This feature provides easy support for variable maximum aperture zooms.
Note: It is a small matter, but important to note that the contacts provide lens state information and are not used for lens control.
Steve
* There are some non-AF designs where the contact state is managed by a simple logic device, but it is easiest to simply consider the array to be hard-wired.
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Forum: Troubleshooting and Beginner Help
10-29-2018, 07:48 PM
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Are you sure maximum aperture/aperture range is transmitted by the data pin with the chip you are using?* Default is to use the mount contact pattern, even on AF lenses. This can be tested by masking the data pin and seeing what maximum aperture is detected.
Steve
* The camera body determines available apertures by calculation from minimum aperture and aperture range as encoded by the mount contacts or provided by polling the data contact.
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Forum: Troubleshooting and Beginner Help
10-29-2018, 09:41 AM
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The "numbers and letters" are hexadecimal numbers (data) from set locations in the lens' read-only memory. Whether your task is doable is hard to say, but since your understanding is minimal, you may not be the person to do the attempt. Failure may brick the lens. Rather than start with hacking the lens ROM, it might help to share why you want to do such a thing.
Steve
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