08-09-2011, 11:29 AM
[quote name='Klaus' timestamp='1312885450' post='10548']
Really ... ?
[url="http://savazzi.freehostia.com/photography/workingdistance.htm"]http://savazzi.freeh...ingdistance.htm[/url]
[/quote]
Well, as long as the lens has an IF design (no change in length while focusing), I think the formula is still valid (or am I missing something?)....
The figures given for Sigma 180mm in this article proves it. The WD was calculated as 232mm for 1:1 ratio. The physical length of the Sigma 180mm f/3.5 is 179,5 mm. The flange focal distance for F-Mount is 46,5 mm and the MFD for Sigma lens is 460mm.
460 - 179,5 - 46,5 = 234mm (not sure about the 2mm difference from the 232mm give in the article, maybe the precise length of the lens was different for the F-mount version).
Serkan
Really ... ?
[url="http://savazzi.freehostia.com/photography/workingdistance.htm"]http://savazzi.freeh...ingdistance.htm[/url]
[/quote]
Well, as long as the lens has an IF design (no change in length while focusing), I think the formula is still valid (or am I missing something?)....
The figures given for Sigma 180mm in this article proves it. The WD was calculated as 232mm for 1:1 ratio. The physical length of the Sigma 180mm f/3.5 is 179,5 mm. The flange focal distance for F-Mount is 46,5 mm and the MFD for Sigma lens is 460mm.
460 - 179,5 - 46,5 = 234mm (not sure about the 2mm difference from the 232mm give in the article, maybe the precise length of the lens was different for the F-mount version).
Serkan