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02-01-2011, 03:03 PM   #1
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Fixing Tamron Adaptall lens-adapter latch

Occasionally, you find an Adaptall lens that doesn't want to lock the lens-adapter to the base of the lens. While it may work OK, it's not a confidence inspiring situation when you're afraid the lens and body will unexpectedly part company.

The fix is usually very simple and the picture should show you all you need to know. The problem is usually one of two things: (1) debris jamming the latching lever (in a dirty lens that needs cleaning anyway), or (2) the flat spring that tensions the latching lever has either overridden the lever and needs to be repositioned or is bent from forcing the adapter.

Remove the three mounting screws. The two bayonet-fitting disks are under slight upward spring tension but not enough to cause parts to fly off.

The thin spring tension disk under the bayonet-fitting disk has very small washers on the under side where you won't see 'em until they fall into the barrel. It's a good idea to make a donut gasket out of rolled tissue paper to plug the cavity in the barrel to prevent parts from falling into the lens and jamming up the works.

Lift off both disks. You might want to index 'em with a marker, but, for a change, the parts can only be re-assembled in one way (although it might not seem so at first).

Clean, reposition or replace the spring as necessary and re-assemble in reverse order. A bent spring can be gently re-worked with needle-nosed pliers. The spring simply slips over the stud - no need to unscrew it.

When re-assembling the disks, a tiny dab of thick grease or glue from a photo-mount glue-stick will adhere the washers to the disk. A toothpick helps to align all parts with the screw holes in the barrel.

The mating parts for the lenses and adapters seems to be identical on all Adaptall lenses so cannibalizing a cheap lens to put an expensive one back in service makes sense if parts are deformed or worn out of tolerance. There seems to be plenty of the cheaper, early lenses available on the internet for donor parts if needed.

[ The Adaptall lenses do use JIS cross-point screws rather than the common Phillips type. A set of JIS bits from MicroTools or other suppliers is a good investment and pays for itself if you've ever 'mushed-out' a tight screw head with a Phillips bit. (see 'JIS screw' article in this forum) ]

H2




Last edited by pacerr; 02-01-2011 at 04:13 PM.
02-11-2011, 01:32 AM   #2
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Join Date: Dec 2009
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Thanks for this post! I have a number of Adaptall lenses and it's good to know there's a fix if I ever need it.
06-21-2013, 09:26 PM   #3
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Join Date: Jun 2013
Posts: 1
QuoteOriginally posted by pacerr Quote
Occasionally, you find an Adaptall lens that doesn't want to lock the lens-adapter to the base of the lens. While it may work OK, it's not a confidence inspiring situation when you're afraid the lens and body will unexpectedly part company.

The fix is usually very simple and the picture should show you all you need to know. The problem is usually one of two things: (1) debris jamming the latching lever (in a dirty lens that needs cleaning anyway), or (2) the flat spring that tensions the latching lever has either overridden the lever and needs to be repositioned or is bent from forcing the adapter.

Remove the three mounting screws. The two bayonet-fitting disks are under slight upward spring tension but not enough to cause parts to fly off.

The thin spring tension disk under the bayonet-fitting disk has very small washers on the under side where you won't see 'em until they fall into the barrel. It's a good idea to make a donut gasket out of rolled tissue paper to plug the cavity in the barrel to prevent parts from falling into the lens and jamming up the works.

Lift off both disks. You might want to index 'em with a marker, but, for a change, the parts can only be re-assembled in one way (although it might not seem so at first).

Clean, reposition or replace the spring as necessary and re-assemble in reverse order. A bent spring can be gently re-worked with needle-nosed pliers. The spring simply slips over the stud - no need to unscrew it.

When re-assembling the disks, a tiny dab of thick grease or glue from a photo-mount glue-stick will adhere the washers to the disk. A toothpick helps to align all parts with the screw holes in the barrel.

The mating parts for the lenses and adapters seems to be identical on all Adaptall lenses so cannibalizing a cheap lens to put an expensive one back in service makes sense if parts are deformed or worn out of tolerance. There seems to be plenty of the cheaper, early lenses available on the internet for donor parts if needed.

[ The Adaptall lenses do use JIS cross-point screws rather than the common Phillips type. A set of JIS bits from MicroTools or other suppliers is a good investment and pays for itself if you've ever 'mushed-out' a tight screw head with a Phillips bit. (see 'JIS screw' article in this forum) ]

H2
I registered solely to say thanks for this fix - after dropping my favourite lens and having to order a new mount, I thought I'd have to spend even more to get it to lock properly. This let me lock that sucker in tight, thanks so much! It really is my favourite lens and you did me a solid.
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