Anyone try this before?

Is there a 52-77mm coupling ring? Cost, place?

I've tried placing the reverse 50mm near the front element of the zoom lense, look thru the viewfinder at 105mm and see a black circular border, vignetting?

Would varying the DOF of the zoom lens be of any use?

I was just thinking that the IS might come in handy this way , but how effective

Share ur insights pls, thanks!