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07-15-2011, 07:15 AM   #31
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In scaning the posts, I have a couple of observations and comments

the mod suggested by Joe Pen is not correct, it is only the last pin that needs to be shorted with foil to the lens mount to disable AF, the other two are aperture pins and shorting them, will, depending on lens give you exposure errors.

Also, if you want catch in focus, you need to have the camera set to AF-S to lock the shutter with focus confirmation.

now for the more relevant question.

do you want to capture the birds, or the action of bird tagging. the lens requirements will be quite different. I think the activity would be much more interesting in the long run than the birds themselves. I could be wrong, but perhaps a lens like a 28-75 would be a lot of use here.

If you are in a yard and the birds are accustomed to people and feeders, a 200mm telephoto should be sufficient.

07-15-2011, 11:05 AM   #32
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QuoteOriginally posted by Lowell Goudge Quote
the other two are aperture pins and shorting them, will, depending on lens give you exposure errors
That is not correct unless the mount has changed since my last lens purchase - the other two pins (and a fourth on the top) are lens data contacts (focal, lens mode, etc..), the aperture contact pin is the second pin down from top center clockwise, as noted. For exposure errors, I fired off 4 or 5 test shots with the sigma and the 3 contacts foiled and all exposed as they should - this could however be different on other lenses, don't see why it would though. Maybe you are correct on the "Last Pin" foil to disable autofocus, didn't test that...
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07-15-2011, 12:38 PM   #33
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Joe

Starting with the KA mount, there were a possible maximum of 6 pins on the face of the lens mount, with a 7th added for the KAF mount, and then the two power pins for the KAF2 mount (power zoom or SDM power contacts) inside the mirror box.

starting at the lens locking pin, there are 2 contacts used for aperture coding, then the A contact, then another 3 aperture coding pins. In total there are 5 aperture coding pins that are used to define the minimum and maximum aperture of the lens, and this "data" is transmitted to the camera body,

the 5 aperture coding pins are either open circuit (insulators or just not connected) or short circuit, (no pin or insulator or the pin shorted to lens mount) depending on the actual lens, and in some variable aperture lenses there is circuitry (sliding switches etc) that change the coding as you zoom.

the A pin is open for using aperture ring and shorted to lens mount for using the A position

the last, 7th pin location from the lens locking pin is the data pin for AF. If the camera sees nothing at all on this pin, you do not get AF confirmation, and on some bodies the shutter will not trip. if it is shorted the camera thinks there is a MF lens attached. if there is data, the camera knows what is attached.,
07-15-2011, 12:55 PM   #34
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Great technical explanation Lowell
QuoteOriginally posted by Lowell Goudge Quote
depending on the actual lens, and in some variable aperture lenses there is circuitry (sliding switches etc) that change the coding as you zoom
Ok, didn't think about that, so exposure issues can occur. Question though, min/max aperture values are not transmitted through one aperture contact? Or is this just pseudo and can be through one or multiple contacts?



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07-15-2011, 01:09 PM   #35
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QuoteOriginally posted by joe.penn Quote
Great technical explanation Lowell

Ok, didn't think about that, so exposure issues can occur. Question though, min/max aperture values are not transmitted through one aperture contact? Or is this just pseudo and can be through one or multiple contacts?



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Joe

min max aperture is a specific contact coding, see the following link as it explains it pretty clearly

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

the coding is done in such a way that it can easily be implemented in dedicated hardware, not just in the camera but from th elens perspective also, as this evolved long before the use of 4 or more microprocessors like my PZ-1 had.
07-31-2011, 05:54 PM - 1 Like   #36
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Here are some photos from that day, it was overall a pretty fun experience.
No flash, had the K7 with 70-200 2.8 and K20d with the 17-50 2.8..

























07-31-2011, 07:12 PM   #37
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I'm glad you brought us back some photos, Slick! You got some really good shots! I don't think I would have believed that you could catch and measure a hummingbird like that... amazing!! Did you learn any new photography skills that day? Were any of the pieces of advice you received particularly helpful? I'd love to hear any of the "tips for bird-shooting noobs" you have to pass along.
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