The U-BXP 100 is a special version of the U-BXP housing. It has a wider front glass and allows in combination with the C-A 77 adapter (supplied with the housing) and C-A 82 (available as an accessory from your dealer) 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 Canon EOS 1D, 1Ds Series as well as the Nikon D1, D2H, D2X, D200 and similar cameras, withmost of the professional wideangle lenses currently on the market. This enables you to use wideangle lenses with a focal length of 16mm (full format chip) without problems. SLR cameras which have a smaller chip can even use the 10mm wideangle lenses. Please note: all lenses used with this housing must have a internal focus. Lenses with a smaller filter diameter can also be used in this housing as long as they have 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. Experienced photographers have confirmed, that the auto focus and flash both 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. (this is the reason why ewa-mar