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04-17-2014, 04:47 AM   #1
Jonathan Mac's Avatar

Join Date: Apr 2009
Location: Madrid, Spain
Posts: 4,343
help to fix a 645 extension tube

Hi all,

I have just today bought a set of 645 auto extension tubes, something I've been looking for for a while. They are in good condition except that the smallest one seems to have a broken/missing spring inside it. The lever which would be on the left if the tube was mounted on a camera and you were facing the front of the camera is loose. On the other two tubes it returns to the upper position.

I have tried it on the camera and it seems to work. I think this lever stops down the lens for the shot, I don't think it's used by the camera to know what aperture the lens is set at to calculate exposure. Is that right?

So my questions are

(1) is this likely to cause any problems when actually shooting film?
(2) has anyone opened one of these up to repair? If so, is it likely to be simple to fix?

Many thanks

09-17-2014, 09:14 AM   #2
New Member

Join Date: Nov 2013
Posts: 1
Hi Jonathan

It should not be a problem. When you attach the tube to the lens the equivalent lever on the lens will engage it so it will be "sprung" and can stop down the lens just fine.

Not sure if this should be a separate thread, but I have a tube 1 that works perfectly on my 645D but not on someone else's 645D. The only difference between the cameras is that mine is still on firmware v 1.13 whereas the other camera is on firmware v 1.3. Has anybody else got experienced this problem and is there a fix?


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