Which mount? Adaptall or Adaptall 2

The adaptall2 could pass max aperture info to the camera. For the NEX system, not going to help, so either mount would work.

If all you have is the adaptall lens, and no intermediate adapter, you can go straight from Adaptall->NEX

 

+1

Less complicated and lighter...

 

Confused.com

 

In the 70's an aftermarket lens manufacturer (Tamron) had a ground breaking idea to get a bigger slice of this market. Instead of making a lens for each brand (Canon, Nikon, Minolta (now Sony), Olympus, etc. all with different mounts), they decided to make various replaceable "rear ends" for all their lenses that correspond to these various interfaces. This was no small feat because all these different brands had different mechanisms that actuate internal apertures for Auto-Aperture modes. They called the system Adaptall, later to be followed by Adaptall2.

The system worked really well, but what made it a success was that Tamron actually made really good lenses - especially the primes. They had some excellent zooms as well, but some not so good ones too.

Tamron now makes aftermarket AF lenses for DSLRs but they've had to ditch the Adaptall system because (I'm speculating) that today's electronically actuated AF lenses cannot be bridged as easily or cost-effectively.