What is your experience with the Zuiko MC Macro 38/3.5?
On today's hi-res sensors, its optical quality is so-so. Its preset aperture is handy. I bought mine for 9,000 JPY, so it's good enough for casual closeups at 3-5x. The working distance at those magnifications is around 2cm, which makes the lighting easier when necessary.
For serious works, you may want to look for Macro Nikkor, Zeiss Luminar, Mitsutoyo, etc.