The helicoid on the 100/4 Macro extends 50mm on its own. Add that to a 50mm tube and you get 100mm extension therefore 1:1 magnification.
Regards, Anthony Farr ----- Original Message ----- From: "Bill Owens" <[EMAIL PROTECTED]> (earlier message snipped) > > Wouldn't an extension tube have to give enough extension to extend the lens > to 100mm (in this case)? I'm under the impression that it takes enough > extension to equal the focal length to get 1:1. Or something like that :-) > > Bill > - - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
