Nikon 70-200mm f/2.8 VRII plus Canon 500D close up filter
Measures: Magnification .387 Reproduction Ratio 1:2.58
I wanted to calculate the magnification of my Canon 500D close-up lens and Nikon 70-200 VRII.
This was shot with a Nikon D200 which has a sensor width of 23.6mm Based on the above, I measure 61mm visible in the frame.
Magnification is 23.6/61= .387 or a reproduction ratio of 1:2.58