No, the lenses are NEARLY identical except for mount. The screwmount is more versatile and has better resale market because it fits way more cameras , not only pentax K, but even other makes like Canon AF with an adapter. Hence given a choice between the two for same price and condition, you are better off getting the screwmount version. There is one other small difference other than the mount, the screwmount version takes 49mm rear filters instead of 52mm rear filters. You also need to be careful buying the screwmount version because the screwmount version came with and without SMC so if you buy the non-SMC version you better save some money as it is still very good but should sell for quite a bit less than the SMC version. JCO
-----Original Message----- From: Jim Colwell [mailto:[EMAIL PROTECTED] Sent: Saturday, August 07, 2004 12:15 PM To: pdml Subject: RE: feedback wanted--SMC Takumar 500/4.5 JCO, If you have a M42 camera then it may make sense to consider that the Takumar is an advantage. Do you have any information that suggests the K and Takumar versions have different optics and/or apertures ? My comments are based on the following quotation from Alex Nemerovsky's site: "K500/4.5 feature very good optical design as well as a preset aperture. It's quite heavy and, unless you want to strain your back and get a fuzzy shot, it should be tripod mounted most of the time. This lens has the same design as the previous Takumar version of 500mm. K500/4.5 lens has a 52mm rear filter." (http://home.att.net/~alnem/html/pentax_primes.html#500) Jim www.jcolwell.ca P.S. the SMC 500/4.5 has a manual aperture, not preset - maybe the other comments are also incorrect(?).
