[Leica] image quality and format

[Erwin Puts <imxputs@knoware.nl>]

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