DOF is a nightmare underwater... My hat would be off for anyone who shot LF underwater just as my hat is off for those 16x20 glass wet plate photographers that ventured into Utah and beyond in the 1850's
36 exposures are not much underwater. I did buy a Nik V 35mm and 20mm with finder in near mint and useable condition for under $500 this summer. That 20mm is needed the 35mm just doesn't quite do the job, in clear water the 20mm seems like a Ziess (or Nikkor... or whatever coated lens you love) out of water.
Sorry to repeat the much more experienced UW poster "MAtt" above. exactly what I was trying to say above.
Wow thanks for posting no idea one of those was made....
The practical upshot of this is that you can get anything if you have the money. If not, you will be a thousand times better off with either a digital camera and a housing or a Nikonos V. The Nikonos has great super-ultrawide lenses since it's a viewfinder camera, plus they are specifically designed to be in contact with water rather than air. Plan about $100 for the camera plus about $200 for your lens of choice, plus strobe. For best digital results, plan on getting access to a Nikon 9000 scanner or a drum scanner. If you get a digital camera, it's essentially this or that, whatever you can get a housing for plus a superwide zoom plus matched dome. Plan on the order of $2500 for this, plus strobe for a DSLR, or $300 plus strobe for a P+S housing.
There's also the PiratePro housing, which is EXTREMELY promising if they ever get it off the ground. Essentially, it mounts Nikonos-V lenses on an Epson EP-1. As mentioned, the Nikonos-V optics are custom-designed for water and are amazing.
Anything beyond this will be extremely expensive. You should plan on 3-5k of expenses to procure a Rolleimarin or a Pentax 67 Marine housing. At least. Also, you only get 20 or 24 exposures, and they'll be less wide than is possible with digital/35mm. While it's possible, I don't regard this as a great option. Unless you are VERY experienced at underwater photography, the instant feedback of a digital camera is worth more than the resolution of medium format.
You might check Ikelite. I have a friend who has used an Ikelite housing for his 500C for years. You also need a flash as it's dark down there.
The Pentax 6x7 has a factory built accessory housing for underwater photography.
Originally Posted by Loose Gravel
You should be able to find one somewhere rather than changing systems.
Good luck. As mentioned already, P67 housings were custom-made to order and there's somewhere around a dozen in the world. I've done a bit of window shopping and they seem quite tough to find. That could probably be overcome by slapping a $5k offer on a board somewhere, but who knows? Again, unless you are willing to commit some pretty serious cash for a housing that will limit your number of shots, the P67 marine housing is a fantasy. You could try it in one of those plastic bags, but they just give me the shivers. I love my P67, but underwater's not the right place for it.
One way you could get around the limited number of shots would be a 70mm back with a Hasselblad, if it fit in the housing. It takes a bulk roll of film that's like 50 or 100 feet long, so you could get a lot more shots before having to surface and reload.
Not just to you (the OP actually said he was pool diving), but in general: give really serious consideration to whether you want to shoot film underwater. The Nikonos-V is a great tool and has amazing ultrawides, but instant feedback is king. You won't be doing that many dives, and underwater strobing does take some getting used to. What would take a few dives to get used to with digital can take a couple trips if you only get feedback once a day. If you're just that good, go hog wild, but underwater is an extremely demanding environment for photography. The Nikonos-V will help with this, because it can meter TTL during a strobe exposure. But, If I had $5k to blow on a housing, I would blow it on an Ikelite housing and a Canon 5d2, plus a good strobe.
If nothing else, consider taking along a second rig with a digital P+S and a housing, along with a small optically-slaved strobe. This won't set you back too far if you have the money for diving with medium format, and it will let you get some instant results for practice.
There are housings for Hasselblad Superwides, and I'm pretty sure most of them will take the 70mm long-roll backs. They're far more common than the housings for other medium format cameras, with the possible exception of the Rolleimarin, which was a factory accessory (granted, they didn't sell that many of those either). But everything else that has been said about medium format underwater is true - I'd get used to shooting underwater with a digital, and only after you're sure you want to keep doing this and you've gotten better at it would I invest in a medium format housing. After digital, get a Nikonos V with a strobe to get used to the film+strobe bit - while the Nikonos V does have TTL strobe, it's still not as automated and idiot-proof as underwater digital is. When you're finally getting good, consistent results with the Nikonos, then upgrade to the medium format. IMHO, the way to go if/when you get to that point is to get the Hassy Superwide with the 70mm back. The 38mm lens is like a 20mm for 35mm/digital, so it'll be plenty wide, and if you couple it to a flash and reasonably fast film, you'll have the depth of field to be able to set the thing at hyperfocal and forget it. There are strobe setups that will work with those cameras too, but I'm not sure of the details on them. The whole medium format underwater thing is a bit of a mystery because it's so unusual.
I think everyone has overlooked that there are digital cameras on the market that go underwater without any additional mods... and sad to say they can do a super job no housing needed... AF works.
I kinda wonder why I got the Nik V earlier this year other than I am an APUG nut.
Don't forget that you can get underwater single-use 35mm cameras. Quality is probably not amazing but you might be surprised. You could just carry more of them for extra shots. It could work for some purposes.