More Experimentation Needed

More Experimentation Needed.

Continuing with my investigations into extreme close up. 

As I could not find my lens coupling ring I decided to get another one, good old Amazon, and it came today.

I really did not have time to play. I popped the 75-300 Canon EF lens onto the Canon 5D Mkiv, fitted the lens coupling ring and a step up adaptor to enable the Canon 50mm f/1.4 to be fitted in reverse.

With this set up I have managed, with both lenes set to infinity, achieve a magnification just a bit more the 1:1. Severer vignetting as you can see but I am hopeful with a bit more time and experimentation to get to 2:1 or maybe even 3:1. 
Quality on this image is poor, Hand held and iso1000.