gr8fuldoug Report post Posted June 11, 2007 Pentax Eyepiece Formula A few people have contacted me in order to figure out the power ratio on fixed eyepieces with the Pentax Spotting Scopes. i thought I would do a post to put the info out. The formula is as follows: Take the focal length of the scope and divide by the focal length of the eyepiece. Example: 80mm (focal length = 500mm) divided by 14mm (xw14) = 35.71 or 36 power. Focal length for the scopes is listed below 100mmED – 625mm 80mmED – 500mm 65mmED – 390 mm Please feel free to call if you have questions. Share this post Link to post Share on other sites
