The Extension Bellows are simple bellows for the older F bayonet. The guide consists of a single round gear rack, only the lens plate can be moved, the camera plate is fixed. With a 50 mm standard lens in normal position, a magnification ratio of up to 2.5:1 can be achieved with these bellows. On the gear rack, magnification ratios are marked for 50 mm and 135 mm lenses. The lens plate can be clamped in any position on the rack by a respective screw.
The Extension Bellows have no coupling for the aperture to the camera body. The aperture must be closed manually prior to exposure. As the aperture of the F bayonet lenses does not close by itself, as it does on the later AR lenses, there is a respective lever on the front of the bellows. If this lever is connected correctly to the lens's aperture mechanism, it will close the aperture by means of spring pull to the value set on the aperture ring. When the lever is pressed, the aperture opens. To connect the lever correctly to the lens' aperture mechnism, it must be pressed while mounting the lens on the bellows.
Different from the later bellows for the AR bayonet, the camera bayonet connection of the Extension Bellows cannot be turned. So if you want to switch from landscape to portrait orientation, the whole set-up of camera, bellows, and lens has to be turned, with the tripod connection to the side.
The lens plate offers no possibility to use the lens in reversed position. If the lens is to be used in reverse position, a Reverse Adapter is required.
There is no matching Slide Copier for the Extension Bellows, the bellows do not have a possibility to couple to it.
An 1/4" tripod socket is placed in the bottom of the camera plate of the Extension Bellows. The lens plate does not have a tripod socket.
The Extension Bellows are very rare. Third-party bellows are easier to find and mostly cheaper, while they frequently offer more possibilities than these very simple bellows.