Carsten,
You had an idea and already skills in diving and knowledge using a LF camera. Few actually carry them through like this. Kudos! Could you add to the thread the story behind this fascinating project! Lots of folk have great ideas?
Asher
Thanks so much, Asher,
Ok I'll just give you a run-down as to how and why it all came about without going into too much detail for now:
Premise:
I had been using large format cameras for over 10 years and done UW photography for almost three decades. In my previous job, a request for mural-sized, very high resolution, unstitched uw images for a public display came up. This coincided with me contemplating why uw-photography basically stops at medium format. Creative advantages, albeit offset by the many disadvantages the large format brings drove my interest. Wanting to get reasonably close to one's subject whilst maintaining critical focus and a decent depth-of-field is usually not a trivial matter in LF, least underwater. I could elaborate, but to cut a long story short: Lens tilt/back tilt and known height of the camera above the substrate were some of the parameters needed to maximise large format DOF across the sea-life on the seafloor, if subjects in the water-column could be neglected.
Built:
I had most of the parts lying about (old aluminium pressure tanks, 5x7 holders, Canham 617 back, 30-odd LF lenses to choose from, domeports, etc.) and access to some engineering workshops, so cost-wise it wasn't going to be an exorbitant excercise, but it still took a fair bit of thinking about it before it all came together. As tilting a lens behind a fixed domeport would have added complication, I decided on basically just tilting the port with the lens. The camera ended up working rather well off the block (minus one relatively minor initial leak, which led to an o-ring position redesign), but I am still making the camera a bit better.
Operation:
To keep things simple underwater, this camera is basically a 3-trick pony:
a)
For maximum depth of field across the seafloor, the camera needs to be positioned at a fixed distance off the ground and the body, film back and lens tilted to a specific degree.
b) in
standard position (e.g. parallel lens and film-plane), DOF is limited and can be used as a creative tool; backward tilt is also possible.
c) changing the lens (before the dive) turns it into an excellent
LF macro camera. The reproduction ratio is fixed at about 1:2.5 for now.
Issues:
Triggering the press-shutter is done electrically at the moment just through a geared micro-motor and a remote-cable and 12V battery pack; I couldn't find a small, but strong enough solenoid. An R/C servo would have worked better, but I was in a hurry.
I have to open the camera in total darkness due to the lack of darkslides, but a modified changing bag does the job when needed.
The aperture is fixed at the moment. I only control the shutter speed via lens gears, but since I want to maximise DOF and I don't have a ground glass, f22 is fine by me anyway. Adding a geared aperture control is rather trivial, I just don't need it at the moment and I wanted to have a simplified "proof of concept" camera working before I added further functionality.
I haven't tried handheld wreck photography, or such yet, as the camera wasn't designed for that; it is more or less an uw "landscape" - tripod based - camera.
Interesting possibilities:
E.g. by using an ND filter, or working in twilight, or at night, everything that is moving (seaweeds, fish, etc) gets blurred out of the picture altogether or becomes a haze due to the extended exposure time. I, or an assistant can just swim along and, using strong (noosed) underwater strobes on poles can then flash individual subjects back into the picture. Multi-exposures in-camera are of course also an option.