My effort to duplicate the spotting scope of Roy Goh (http://www.pbase.com/roygoh/homemade_digiscope) has begun with a bang. I've just found the same Plossl eyepiece he bought ($6.50 on surplusshack.com) and I'm trying to decide between an OBJECTIVE LENS, 38MM X 297MM FOCAL LENGTH ($7.50) and a Double convex lens with 50mm diameter and 200mm focal length ($3.50). Goh used a 200mm fl objective, but wouldn't the 297mm fl be better? However, the 200 is 50mm in diameter, whereas the 297 is only 38mm in diameter. I would think a bigger objective would be better---wider field of view. So I'll probably go with the 50mm/200mm fl lens.
Any advice from someone in the know? I'm just totally impressed that I'm getting two lenses for like ten bucks. Woo-hoo!