Image "squareness" is my fault, main aim was to get top edge close to frame top. I just put the old lens test board on the back lawn and took a few quick hand-held shots. They were hand held shots to get reality into the tests, maybe a more careful setup with a tripod would help, but that's not the way I use the camera. For some reason with holding a camera and viewing the image via the LCD, accurate framing seems near impossible. It's a matter of shakes and body movement and holding the camera away from the head.
As you can see, slight barrel distortion at wide, a whisker of pincushion distortion at middle and a very tiny whisker of pincushion at max tele. All this is never noticed in normal use and if needed can be very easily fixed in an edit program.
With normal shots there is no problem at all with any corner darkening or vignetting. There may be a tiny amount at times but it is insignificant.
I made the original images greyscale in all cases and then took 100x100 pixel crops of centres and corners. Then did a resize to 200% to better show the pixels. No sharpen, just as it is but set to greyscale.
The top right corner happened to be neither the worst or best corner. Cameras will differ, but my R3 bottom left corner is worst and bottom right corner is best it seems.
Settings that happened (auto) for the test shots were....
4.6mm (28mm) was at f/5 1/570 sec ISO 64
14mm (85mm) was at f/4.8 1/620 sec ISO 64
33mm (200mm) was at f/4.8 1/810 sec ISO 64
As usual a test taken of a black and white test panel is a bit unrealistic but it does allow some way of making comparisons at different focal lengths.
Although the pixel peepers may be worried about the look of these crops, rest assured that the full size image viewed normally looks very good indeed at all focal lengths. Test was done at the step zoom settings of 28, 35, 50, 85, 105, 135, 200 equivalents but only 28, 85, 200 shown here.
My conclusion - this little camera has an excellent lens. It's actually quite impressive considering the tricky design to get that 7.1x zoom and the double folding lens arrangement to make it compact.
My feeling is that at 33mm (=200mm) the performance seems best, but of course depth of field issues are more a worry then. Many competitor cameras are at their very worst at maximum tele setting, so this Ricoh lens is really a little gem.
If you choose the Scene mode Macro, the lens will set to 9.6mm (=58mm) which I guess that Ricoh feels is best for critical macro shots.
