Probably the first extinction meter to be widely available. The meter is held against the ground glass screen, a disc perforated with a series of holes is rotated and viewed through a slit in the meter case. The extinction point is when three small holes become indistinct whilst a larger hole can still be seen. This gives a value which is then found in a table giving the exposure time required, the reading is taken with the working aperture set on the lens. The text on the printed label varies. In Britain the meter was sold by the London Stereoscopic Co.

This meter has two movable variable density wedges, one is set to the diaphragm to be used, the second wedge is then moved to the indistinct point, the shutter speed and aperture can then be found against the plate speed. Degen was established in 1865.