I have been on a quest to shoot some small critters (we have pygmy seahorses at two local sites, and lots of other stuff) and looking to get ever closer. But UW gear is hard to get here and expensive and I could not find the sort of lens comparison that I needed to be confident of having the capability that I wanted. I was also curious about the running debate about the Olympus 12-50 lens and whether it is worthwhile getting the expensive Nauticam port and gear to access the 43mm macro mode or just using the 50mm normal mode plus a diopter.
So I put together this simple and somewhat unscientific test to show what is possible with the lenses commonly used by Olympus m4/3 shooters. Lenses are the Olympus 12-50mm zoom and 60mm macro. Diopters are the Subsee +5 and +10. Camera is an E-M5, housing is Nauticam, and port is the Nauticam with zoom gear. The nudibranch "model" is plastic! Cutting to the chase, here is what I found:
60mm macro: Maximum native magnification obviously, diopters take it to 2.5:1 and provide closer focus but not much magnification difference between +5 and +10 diopters, very short working distance with diopters is a challenge.
12-50mm using 43mm macro mode: Usable native macro but not good enough for the smallest targets, not much additional magnification with diopters, working distance with diopters probably too short.
12-50mm at 50mm normal mode with diopters: Using the +10 produces results very similar to the 43mm macro mode with a useful extension to working distance. However not good enough for my purposes.
Data and photos follow. Full size versions can be found here: https://www.flickr.c...157656370044855
60mm macro with +5
60mm macro with +10