Archived posting to the Leica Users Group, 2006/10/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Just to add. I mentioned that the industry had generally used a CoC of 0.03 mm for 35 mm lenses. How is this 0.03 mm derived? As mentioned in Wikipedia, using the so-called ?Zeiss formula? the circle of confusion is sometimes calculated as d/1730 where d is the diagonal measure of the original image (the camera format). For full-frame 35 mm format (24 mm ? 36 mm, 43 mm diagonal) this comes out to be 0.024 mm. A more widely used CoC is d/1500, or 0.029 mm for full-frame 35 mm format, which corresponds to resolving 5 lines per millimeter on a print of 30 cm diagonal. Values of 0.030 mm and 0.033 mm are also common for full-frame 35 mm format. Since d is smaller for a digital sensor that is less than 24x36 mm, it is clear that a 35 mm lens used with a digital sensor must have a smaller DOF at all distances. Hence, the DOF markings now on our Leica lenses are no longer correct when you put them to use on the M8. Send instant messages to your online friends http://uk.messenger.yahoo.com