As an introduction to macro, I am using a Canon FD50 mm f1.8 (from my 1980's AE-1) with extension tubes & mount adapter to my micro 4/3. I have made a robust, accurately height adjustable stand with diffuse lighting, and expose at f16, ISO 200, using 2 sec delay. The resulting images are reasonable but not as sharp as I had hoped. eg. the veins in a fly's wing (when in focus) are distinct but not sharp. Secondary veins if present are not visible. have also tried an FD28 mm f2.8 and FL 50mm f1.8, and can see no discernible difference.
Can anyone please suggest an FD or compatible mount lens which may give better IQ. At worst, I could stretch to another adapter and tubes for a later series lens.