Huck, are you talking about focal length or about physical length of the lens. If physical, the only guide you have is to measure them yourself, there is no standard on that. If it is physical length, there can't be a large variance as the focal length is from the optical center of the front element to the film/sensor plane. Of course some lenses have extra added on, I guess as a lens hood. My 200mm for my EXA has about 2 inches protruding and not collapsible.
Photography: the art of seeing the uncommon in the common.
Zorkii C, 2C, 4, 6
Fed 2, 5A
Zeiss Ikon Nettar 515/2, Nettar 517/16, Baby Ikonta 520/18, Nettar 519/2, Ikonta 520/2
Retina I, Retina IA, Retinette IB
Various Agfa and Agfa Ansco RF
Kiev 3A, Kiko Sumi, Balda Baldette
Kiev 88CC camera & lenses
EOS XT, Sigma 28-80/3.5-5.6 macro, Zenitar 2.8/16mm fisheye
Canon F1, 28mm FD, 200mm FL, Soligor 250mm/4.5, Vivitar 90mm macro