I recently bought a used set of APM Binoculars. Over the years, the specifications have changed somewhat and the manual only says I have something in the 800000 series. The eyepieces which came with it are 20mm and 10mm SWA yielding 20x and 40x. So, I must have a 400 mm focal length. But the person I bought them from said the eyepieces yielded 25x and 50x. The tubes don't seem long enough for this to be so, but I don't know how much the prisms or any additional optical elements add to the fl. Does anyone know when these were made, how many elements in the objective and what type of glass in the objective. They accept and bring to focus my 24mm Panoptics and 13mm Naglers. Thanks for any information. BTW they perform very well.