View single post by Robert
 Posted: Sat Jun 29th, 2019 17:11
Robert



Joined: Sun Apr 1st, 2012
Location: South Lakeland, UK
Posts: 4066
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 I'm not truly technically expert in this but my understanding from reading many articles and posts on close up photography by technically proficient photographers is that 1:1 ratio is a pure lens process.  If you photographed a measuring ruler at 1:1 the image on the sensor or film would be exact same size as the original measuring ruler, the image projected onto the imaging medium would be identical in size at both the subject and the capture point, irrespective of the sensor (or film) size. 

Obviously when displayed on a screen or printed from a negative the resulting image could be much bigger than the original article.  I suspect that's what an advocate of the term macro, for less than 1:1 might argue but the pure meaning of macro is 1:1 or greater at the sensor, not the print.

As for the 'macro' setting on a lens, I suspect there is a close range correction mechanism, which moved certain elements to allow closer focus. Some lenses have a distinct change in the focus movement when they enter their 'macro' mode.



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Robert.