One thing I meant to say yesterday was to always be careful when lenses end up very close to the glass - I’ve seen a few times problems when the housing compresses underwater (more port sections - more o-rings - more compression), the port then pushes the lens and camera back in the housing enough that the push buttons on the back of the housing start activating.

1 hour ago, Alex_Mustard said:

One thing I meant to say yesterday was to always be careful when lenses end up very close to the glass - I’ve seen a few times problems when the housing compresses underwater (more port sections - more o-rings - more compression), the port then pushes the lens and camera back in the housing enough that the push buttons on the back of the housing start activating.

Good advice, Alex. In fact, the shortest option is really tight (basically the space of a business card), so I’m a bit worried about it. Anyway, I also tried the 97mm + 20mm combo and it's fine — there’s no vignetting with the close-up lens (SMC-1) mounted on the flip. So this is probably the best option: fewer extension rings, less bulky setup... (until the proper port will be available)