Hi Joe, I don't know how to calculate closest distance, but the diopter of the closeup lens indicates where "infinity" focus would be in fractions of a meter. In other words, the farthest you could focus with a +1 closeup lens is 1 meter, with a +2 it would be 1/2 meter and a +3 would be 1/3 meter and so forth. Hope this helps.
William in Utah. 9/11/2002 3:47:42 PM, "Joseph Tainter" <[EMAIL PROTECTED]> wrote: >How does one calculate the effect of a close-up lens? (That is, so as to >know what to order by mail.) The Sigma 70-200 f2.8 EX that I picked up >earlier this summer focuses only to six feet. I'd like to pick up a +1 >or +2 close-up lens to carry with it. So how does one calculate what the >closest and farthest focusing distances will be with a +1 or +2 lens and >the Sigma at 200 mm.? > >If anyone knows the answer, could you let me know personally as well as >reply to the list? I'm a no-mailer, and Mail-Archive.com seems to be >losing messages these days. My e-mail is: > >[EMAIL PROTECTED] > >Thanks, everyone. > >And thanks, Doug, for getting us no-mailers back on line. > >Joe > > >
