> No, mine certainly are 1 element. > -frank Hi, if I recall correctly, the proxars made for 645 and 67 lenses were 2-element at least. Dunno about the sizes, but I doubt 49mm. Pentax's proxars made for 135 format lenses are all single element. There is a weblist of all proxars with more than one element, btw. Searching for it should get you the address (I don't have it). IIRC there were some Tokina, Canon, Nikon, and the Pentax MF proxars which were achromats (2-element lens design). There is also a very good option of using an 50/1.4 lens SCREWED onto your on camera lens as a proxar!!! It works surprisingly well, as the 50mm lens is inherently better corrected than measly 2-element (or god forbit 1-element) proxars. Commercialy the coupling rings (male-male filter rings) are available commonly from most filter and camera producers. Mounting a 50mm lens onto a 200mm lens will give you, IIRC, 4x lifesize magnification. 50mm on 50mm lens will give you exactly lifesize magnification with very high degree of correction, and almost no life loss as with extension tubes (of course, the "CU" lens must be of faster aperture so not to cause vignetting).
Frantisek
