A superb design for use with Pentax's awesome PF-series of 65mm, 80mm & 100mm spotting scopes, the PF-DS1 adapter is specified to work with the Optio S, Optio S4, Optio S4i, Optio S5i, Optio S5z, S6 point and shoot digital cameras. However, since it threads directly into the eyecup-side of the XW and XF series 1.25" eyepieces, it seems that the PF-DS1 could be used with any telescope or spotting scope accepting traditional 1.25" eyepieces provided, of course, you were using that scope with the Pentax XW or XF eyepieces.
To use the PF-DS1, first unscrew the rubber eyecup from the XW or XF eyepiece.There will be an exposed threading which the PF-DS1 will screw into directly, and then you just insert the eyepiece into the spotting scope as you normally would. Next, attach the digital camera and press it against the four rounded protrusions which keep the camera's sensor parallel to the image. You then turn on the camera and adjust the zoom position upon the digital camera to eliminate vignetting and finally you'll focus with the spotting scope itself.