1. 80 degree lens
2. 80 degree lens plus flip macro
3. Flat port
4. Flat port plus flip macro
5. Flat port plus Century Optics +3.5 achromatic diopter (which the UPS man just showed up with

The reason I thought of this is because I really want to compare options 4 and 5.
My initial plan was simply to video a ruler in the local pool to see how much magnification I can get, then record the exposure settings and the distance from the port to the ruler. Will be 1080i50, gain zero, shutter 1/50 and fix the iris at around what the auto exposure gives me.
But any other suggestions or things you want me to test while I'm at it?
I was wondering about maybe printing and laminating a chequered pattern so we can have a look at the chromatic aberration. What sort of a pattern? Just black and white or colours too?
Then I thought I might include a 2nd ruler almost in line with the camera (90 degrees to the first one) so we can get a judge on depth of field as well.
Also I might fix the subject-to-port distance to say one foot and then compare the achieveable magnification from the 5 options.
Anything else?