After seeing Brian May's (of Queen fame) stereo photos at http://www.londonstereo.com/index.html and seeing that I can buy a Owl print stereo viewer from them; I dug out my old Russian slide stereo unit to try on my K5. The unit was designed to be used for 35mm slides with a 58mm lens. For digital prints I need either a 35 or 40mm lens that can be manually focused AND the lens front element must not rotate when focusing. Could any of you guys tell me which KA or DA lenses in 35 & 40mm have these two qualities. Thanks.