Mamiya 645 adapter to Eos - problem to mount

[Demodres]

Hi RFFs..

Today I received a Mamiya 645 to Canon Eos adapter..it´s a very simple and cheap model from this seller.. http://www.ebay.com/itm/Mamiya-645-...ount-Adapter-60D-7D-5D-M645-EF-/281182322564?

The adapter seems fine but I can´t mount it to my 645 lenses..it fits well in between the first 3 elements, but I can´t turn/screw the adapter to the lens..there is a small metal knob on the side of the adapter which releases some more space inside the circular rings of the adapter. However, pushing to the knop doesn't allow me to mount the lens..(?) I have tried with 3 different 645 lenses - all with the same result/problem...

Have I misunderstood something on how to attach/mount the lens - or have I received a bad version with some wrong inside dimentions?...

hope someone can help me with this problem as I really looking forward to try MF glass on my dslr..

Thanks, Andreas

 

[Demodres]

have anyone tried these adapters and faced similar problems..? any advice on how to overcome the problem is highly appreciated..

One option could be to un-tighten the small screws/bolts on the adapter, which will allow more space for the lens´ outside rings when turned on to the adapter..however, I will hope that I don´t have to do some DIY with the risk of breaking the adapter..