It's not just the Mini35 adaptor you will need Mark. Focusing is so critical (you still need to shoot wide open to achieve the shallow depth of field) you will also need a follow focus attachment. Locked on a tripod an assistant pulling focus is handy but to go handheld then an assistant with a remote control to the follow focus becomes a necessity. On most of these adaptors the image in the viewfinder is upside down, so an external camera monitor connected upside down to the camera is a bonus

Here's three of the leading prosumer brands on the market

The Adapter Place
Welcome to shoot35!
Redrock Micro: Create the Cinema Experience

And if you're useful with your hands a DIY mini 35 adaptor

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