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04-01-2008, 10:14 AM   #1
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For Vivitar MFTC owners

Lately, I've noticed something odd with one particular piece of my gear. My Vivitar teleconverter, although it's marked as P/K-A, didn't communicate aperture information from the lens to the camera. That's slightly odd, because it has all the necessary electrical contacts. After cleaning the contacts, which had no effect, I decided to open it up, since there must be an electrical fault inside the body of the converter. After removing the rear lensmount, which is attached to the optical assembly, I could plainly see the problem. Because the Vivitar is a helicoid-focusing teleconverter, which means it can extend to become an extension tube as well, it couldn't simply directly wire the rear contacts to the front contacts. Instead, the designers used copper springs to provide contact between the two sets of contacts. Three of those springs had come unmounted from their seatings. I used a pair of tweezers to reseat them, replaced the lensmount and optical assembly, and all was well. Now, whatever A-series lens I mount on the Vivitar provides full automatic function.

If you've been having a similar problem with your TC, I recommend you set aside half an hour, and perform this quick, easy fix. I suggest you put the rear lensmount into a Ziploc bag while you're doing it, to protect the front and rear lens elements. Because the optical assembly comes out with the lensmount, there's no risk of damaging the actual optical component of the TC. Your only risk is to the (already damaged) electrical system.

04-01-2008, 10:32 AM   #2
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Thanks for posting this. My copy works fine, but this should come in handy if I ever encounter this problem.
04-01-2008, 10:33 AM   #3
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QuoteOriginally posted by JMS Quote
Lately, I've noticed something odd with one particular piece of my gear. My Vivitar teleconverter, although it's marked as P/K-A, didn't communicate aperture information from the lens to the camera. That's slightly odd, because it has all the necessary electrical contacts. After cleaning the contacts, which had no effect, I decided to open it up, since there must be an electrical fault inside the body of the converter. After removing the rear lensmount, which is attached to the optical assembly, I could plainly see the problem. Because the Vivitar is a helicoid-focusing teleconverter, which means it can extend to become an extension tube as well, it couldn't simply directly wire the rear contacts to the front contacts. Instead, the designers used copper springs to provide contact between the two sets of contacts. Three of those springs had come unmounted from their seatings. I used a pair of tweezers to reseat them, replaced the lensmount and optical assembly, and all was well. Now, whatever A-series lens I mount on the Vivitar provides full automatic function.

If you've been having a similar problem with your TC, I recommend you set aside half an hour, and perform this quick, easy fix. I suggest you put the rear lensmount into a Ziploc bag while you're doing it, to protect the front and rear lens elements. Because the optical assembly comes out with the lensmount, there's no risk of damaging the actual optical component of the TC. Your only risk is to the (already damaged) electrical system.
Nice work! Also, be *extremely* gentle and cautious when removing lens or body mounts and do it on a tray with raised edges... otherwise you are liable to lose a tiny spring or screw or bearing

(I've done it ... fortunately on a broken body)
04-01-2008, 05:05 PM   #4
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QuoteOriginally posted by moxfyre Quote
Nice work! Also, be *extremely* gentle and cautious when removing lens or body mounts and do it on a tray with raised edges... otherwise you are liable to lose a tiny spring or screw or bearing

(I've done it ... fortunately on a broken body)
Certainly be cautious. However, the need for caution with the Vivitar is not as much as other things. Rather than having bearings pushing through holes by springs, it uses small pins mounted on springs. I had no problem in pouring the 7 pins into a small dessert bowl. If anyone wants photos, I would be perfectly happy to dis- and re-assemble the TC again, this time with photo documentation.

04-01-2008, 11:19 PM   #5
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QuoteOriginally posted by JMS Quote
Certainly be cautious. However, the need for caution with the Vivitar is not as much as other things. Rather than having bearings pushing through holes by springs, it uses small pins mounted on springs. I had no problem in pouring the 7 pins into a small dessert bowl. If anyone wants photos, I would be perfectly happy to dis- and re-assemble the TC again, this time with photo documentation.
Well, you are more skilled than me I have sent those 7 little pins flying, never to return, while incautiously opening a lens mount. Oops
04-01-2008, 11:51 PM   #6
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Interesting... I have this problem with a standard (non-macro) Vivitar PK-A TC. I think I'll open it up and see what's going on.
04-02-2008, 08:47 AM   #7
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