Archived posting to the Leica Users Group, 2000/03/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]There is some confusion about the topic identified in the header. When talking about image quality we have three variables: the optical quality of the lens, the negative format and the enlargement factor. You can not discuss these topics meaningfully when mixing them together. My original statement was simply this: The Leica lens has better optical quality than the Hasselblad lens. When the Leica lens records 40 lp/mm and the Hasselblad also 40 lp/mm, but with reduced contrast, the Leica lens is optically the better one. Because 40 lp per millimeter is an absolute number. A square millimeter on a Hasselblad negative is identical to a square millimeter on a Leica negative. So when both lenses record an object at identical reproduction ratio, the Leica has per square millimeter better quality. So if we would enlarge that square millimeter with the same enlargement factor, the Leica lens would win, assuming the same film of course. So optically there is really no dispute or contest. Now the format. A 35mm negative has an area of 864 square millimeters. To make the 6x6 format comparable, we need the same 2:3 ratio for the Hasselblad negative and that is 38x56mm or 2101 square millimeters. So the Hasselblad has an advantage of 2.5 times for area. That implies that the same object that fills the frame in the Leica case, will fill the frame in the Hasselblad case with an advantage of 2.5 times. So now we have the situation that one square millimeter of image area in the Leica case has 2.5 square millimeters in the Hasselblad case. Assume that we need the limit of 40 lp/mm for the object details when taking the picture with the Leica. We need only 16 lp/mm for the Hasselblad picture to cover the same detail at the equivalent resolution. So OF COURSE the Hasselblad negative has a big advantage. Now the third part of the equation: the enlargement. If we use the same enlargement factor of 10 for the Leica negative and the Hasselblad one, the Hasselblad advantage is lost. OF COURSE the resulting print will be much bigger in the Hasselblad case. But we were talking about the optical quality. Now if we assume the same print area, than OF COURSE the Hasselblad negative needs to be enlarged only 0.4 times the enlargement factor of the Leica negative. Now the limiting factor here is the quality of the film. If we can use a film that has a granularity size and resolving power that is below the enlargement ratio of the Leica negative, I dare to say that there will be no difference in print quality. That would be the case with Technical Pan. If the granularity threshold is in the just visible limit than of course the Hasselblad print would show less graininess and will reproduce the subtle shades of grey and the smallest details with greater clarity. No doubt here. So what is bottom line the situation: Optical quality: advantage Leica Negative area: advantage Hasselblad Quality of the emulsion: depends Print size and print quality: depends So when discussing these topics let us be aware of the variables and their interdependence. Erwin