It has a wider frontglass and allows in combination with the C-A 77 adapter (supplied with the housing) and C-A 82 adapter the use of lenses with a filter thread of 77 and 82mm. This means you can use your professional digital SLR camera like the Nikon D1, D2H, D2X, D200 and similar cameras, with most of the professional wideangellenses currently on the market. This enables you to use wideangel lenses with a focallength of 16mm (equivalent to 35mm film or full frame sensor) without problems.
Lenses with a smaller filter diameter can also be used in this housing as long as they have an internal focus. You just need the right step-up ring. The autofocus adapter (AV110) is not included in delivery as it is not needed for this housing. If the optional BF1 lead weight is inserted into the housing, underneath the camera, it becomes even easier to reach the maximum depth of 20 m / 60 ft. Experienced photographers have confirmed, that the auto focus continue to function perfectly.
As you descend, the air is pressed into the camera. Due to this, the pressure inside the housing will remain the same as the surrounding water pressure. Due to this, one has to start the dive with a suitable amount of air inside the housing. The foam pads supplied with the housing are part of this air "reservoir" and additional air should also be blown into the housing, via the valve at the rear, to ensure that the maximum potential volume is being utilised.
The U-B 100 housing is manufactured from double laminated PVC and has an integrated, optically neutral flat glass port. You can also use the internal flash. It has a pair of non-corrosive and seawater resistant clamping rails which fit together for perfect sealing. They tighten by means of three screw knobs.