Has anyone tried a screw-in 0.7 wide adaptor on a lens to get a wider FOV?

[powervideo]

Long subject title, but just wondering if anyone has tried attaching a 0.7 ot 0.6 wide adaptor onto the front of say, a Zeiss 28mm, to get a 21mm type effect, then fitting the lens/wide combo to the DOF adaptor?

Would this work or does the macro function make this not possible?

 

[smithy]

I tried it on a sgpro rev3 non flipped. Didn't turn out the way I like so i chose just to use my 24mm instead. All the extra glass created a lens flare effect. I just got my new flip so I will see if that will help reduce the flare with the new achromat.