Hi Serban,I missed your reaction, sorry. That non square sensor is even more out of the box than the rest... A super wide angle with zero distortion is less easier to make than a sensor with say 10% distortion, how weird it may be. But maybe the idea goes wrong because of higher order distortion. In that case you still have to correct a picture in the computer and it would be easier to have a square sensor anyway. Correction maybe can be doen in the camera even?
kolas: Seems the traditional definition of macrophotography linked to 1:1 or greater lens magnification received a lot of attention in the comments. The truth is, times have changed since film days. Resolving power of today's digital sensors (especially those in compact cameras and cellphones) greatly exceeds that of any film. Therefore one can capture similar amount of detail with camera setups of various sizes.
Example: Take 12MP fullframe Canon 5D with a 100 mm "true macro" 1:1 magnification lens and a 12MP 4/3 camera with a 50 mm "fake macro" 1:2 magnification lens. The same FOV, the same perspective, very similar level of detail captured. But according to the traditional definition, only one of the photos is a true macro photograph! Does that make sense? To me not so much.
Let us redefine macrophotography!
Thanks Kolas for this calculation. My best combination gives 428 pixels per mm, so smallest details are about 3 microns. I did not realize that the micron was so nearby.
I do not use magnification, I only need to know how to measure the length of say an insect under certain standardized circumstances. With a Sigma 150 macro on Olympus E-3 at closest focus I have 210 pixels for a millimeter. With a 2x extender it becomes 428 pixels to a millimeter.
But now something very strange. At a holiday I did not want to carry too much so only took my 18-180. At close focus and f=180 it uses only 53 pixels to a millimeter. I bought a 5 diopter close focus lens and it became 107 pixels to a millimeter. But in the field strange things happened when focusing so I did new tests and found out I had to move backwards and to focus on infinity to have the biggest magnification! Now it is 190 pixels for a millimeter. Completely contrary to expectation, unexplicable, but very useful for identifying small insects! Of course the optical quality of the combination is not extremely good. Just to let you know. Maybe I should buy a close focus lens for the Sigma too.