What is Dynamic Range in Reference to Scanning?
A larger dynamic range is very important when scanning positive film (slides) and negatives. Dynamic range is a logarithmic measurement of image brightness or density that ranges from 0 to 4, where 0 is pure white and 4 is very black. To calculate a scanner’s measured performance of dynamic range, you would subtract the measured maximum brightness (say 0.4) from the minimum (say 3.4) it can capture, and it would have a dynamic range of 3.0. Greater dynamic range is required for greater image detail, especially in shadows and highlighted areas. The problem with the dynamic range specifications shown in advertising for scanners is that it is a theoretical number based upon the number of bits in the A/D (Analog to Digital) converter, seldom on any measurement indicating the actual performance of the entire scanner. There really are differences between $50 – $500 – $5,000 scanners, even if they all have 36- or 42-bit A/D converters.
