not all lens contacts are made equal

Started Aug 20, 2007 | Discussions thread
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glasbak Regular Member • Posts: 390
not all lens contacts are made equal

I thought my LBA (and BHBA, braun hobby buyers addiction) was cured, but last sunday I visited the yearly 'fotografica' event, and picked up some stuff :

Among these a smc-f 35-105 zoom, clearly abused and opened by a previous owner, but it went for a very low amount.

At home, mounted at the also bought as defective P30T , but with battery now working

With the F lens in the A setting, it showed 'P' in the viewfinder so this looked OK.

Now mounted on my istD, it refused to see the A setting, so something is wrong with the contacts.

On the outside nothing looked wrong, metered with a multimeter, and the A setting shorted the 'A' pin to the bayonet, so far so good.

Well, then there must be something wrong with the chip inside.

Opened the lens almost completely to get access to the chip, measured from chip to lenscontacts and nothing wrong, no broken flat foil etc.

Well, I assembled the lens, and made some testshots with the istD, still no working 'A' setting.

But in the exif, it was clear that the chip worked well, lens name was there, used focal length, but for aperture '-.-'.

now I picked up another broken lens from my pile of glass, a smc-f 35-70.
This one at least had a working 'A' setting, maybe I could swap the chip ?

But then I noticed a very small difference.

Not all lens contacts are the same, some extend a little more out of the bayonet !

And the camera 'A' pin is slightly recessed, the previous lens disassembler did exchange some pins.

I rearranged the pins and now have a working smc-f 35-105 lens !

George

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