Does anyone have any insight or knowledge on the maximum gap from the lens face to the port glass for a nauticam wet lens ( SMC-1, MFO-1, MFO-3 ) to focus through?

I have a canon 5d IV that I use in an ikelite housing and located a flip adapter to allow 67mm threaded wet lenses to be used. I tried it out with a nauticam SMC-1, with bad results. I'm using a Canon ef 100mm f2.8L lens, the lens sits approx 1" behind the port glass when assembled(no way to change this) The adapter places the SMC-1 essentially right on the port glass, Making the effective distance from the lens face to the SMC about 1"

I took it out on a couple dives and I couldn't get it to focus at all, is this possibly a user issue or hardware combo issue? Im concerned the issues may be caused by the interior "gap" from the lens to the port glass

Any help is appreciated!

Is this tested in air or in water? As I understand it the diopter power increases in air compared to water, so the focus point comes in closer. That combined with increased spacing may be enough that it focuses inside the lens. If you have not tried it in water perhaps do that first? If it is still an issue are there any alternative ports you could try? For example the 5502 port for 60mm macro in combination with a 1"extension. Looking online it seems FL ports are discontinued so you would be looking for second hand ports.

I have taken it out 2 dives(I shore dive weekly here at home in Kona) and both times I had no success with it. The 60mm macro is not compatible with the canon FF cameras sadly. I have both versions of the EF mount 100mm(but I only bother to bring out the 100mm 2.8L anymore) but neither of the 100mm come close to the end of the port

Also like you said, the FL system is defunct and finding ports is near impossible. The current flat port I am using is the "correct" port for this lens from Ikelite. The modular system is not compatible with the FL housings, so I have to make do with what I can find

PS - @Chris Ross I'll be in Sydney for 2 weeks starting 08/29 - planning a few dives at clifton gardens, the steps, bushranger bay, a seal dive at martin island, and a few more at bare island. If you have any other recommendations or are open to hosting tourist dive buddies, shoot me a PM! My wife and I did our honeymoon in Australia (half in Sydney half on the GBR) and we loved the shore diving in Sydney, so we're coming back for more

You might be surprised at how well the 60mm works on FF, at least as you get close to maximum magnification.

1 hour ago, Grantmac said:

You might be surprised at how well the 60mm works on FF, at least as you get close to maximum magnification.

My understanding was the 60mm is too deep and can hit the mirror in the 5D, am I mistaken on that?

I do use the 50mm regularly under a mini dome and im always very happy with that combo

I have ports made by Saga to use Nauticam wet lenses via a bayonet adapter on my Seacam housings.

This gallery has several pix and flix showing them in use: https://www.salmonography.com/Salmonid-Topic/Family-ties

The lens front element is very close to the port glass. In order to use the EMWL with the Nikon 60mm lens Saga made the port a few mm longer for me in order to accommodate the required diopter lens inside the port per Nauticam. I gather Saga makes these ports to order. Jose is a very good communicator via email (fill in the order form on the Saga web site to get started). Make sure to have them notched like the Nauticam ones.

See: https://sagadive.com/en/product/frontales-conicos-delrin-saga/

Scroll down to see the various lenses and housing brands accommodated.

12 minutes ago, Tom Kline said:

I have ports made by Saga to use Nauticam wet lenses via a bayonet adapter on my Seacam housings.

This gallery has several pix and flix showing them in use: https://www.salmonography.com/Salmonid-Topic/Family-ties

The lens front element is very close to the port glass. In order to use the EMWL with the Nikon 60mm lens Saga made the port a few mm longer for me in order to accommodate the required diopter lens inside the port per Nauticam. I gather Saga makes these ports to order. Jose is a very good communicator via email (fill in the order form on the Saga web site to get started). Make sure to have them notched like the Nauticam ones.

See: https://sagadive.com/en/product/frontales-conicos-delrin-saga/

Scroll down to see the various lenses and housing brands accommodated.

Thank you! That looks to be a great option. I'll email them and inquire

8 hours ago, llamasayswhat said:

My understanding was the 60mm is too deep and can hit the mirror in the 5D, am I mistaken on that?

I do use the 50mm regularly under a mini dome and im always very happy with that combo

A yes mirrors, those pesky things. I'm adapting to Sony FF mirrorless.

That's not quite the combination you are after, but I used to shoot the Sony 6000/6300 with the 90mm macro in an Ikelite housing, with the flat ports 5516.50 and extension 5516.70, and the SMC-1 with a 67 adapter. Not with a flip adapter, I was screwing/unscrewing it as needed, which was a hassle, but then the SMC-1 was closer to the port.

The combination worked flawlessy, and I got super sharp images out of it. I don't have the gear anymore, but I remember that the front element of the lens was very close to the glass element of the flat port... maybe about 2-3mm? And the distance from the lens to the SMC-1 was then maybe 1 cm?

I changed after that to a Seacam housing, but found the SMC-1 more frustrating to use because the 90mm lens was farther back from the flat port and gave a much narrower focusing range. And it became less frustrating after switching to the 100mm macro, which is comparatively closer to the flat port.

This photo was taken with the A6300 + 90mm macro + SMC-1. Some cropping, but so sharp!

Maybe try without the flip adapter, just screwing the smc-1 on the flat port, and see what you can get. Easier than creating a new custom extension.