[Leica] apo 90 versus 4/150

[Erwin Puts <imxputs@knoware.nl>]

The comparison between the Leica APO-Summicron 2/90 asph and the 
Hasselblad 4/150 is based on the published MTF graphs. As Zeiss and 
Leica use comparable methods of MTF generation you may compare them. 
The story that Zeiss publishes actually measured  curves and Leica 
theoretical ones is not true. The comparison then:
Hasselblad at f4
At 10 lines the contrast figure runs from 86% center to 76% corner: very even
At 20 lines: 74% to 60%
At 40 lines: 48% to 40%.

Leica at f/4
At 10 lines: 96% to 96%
At 20 lines: 90% to 87%
At 40 lines: 72% over 80% to 70%

Now at the enlargements we were talking about the 20 and 40 lines are 
the most important. For the 40 lines we have  a 50% gain for Leica. 
That is quite a bit and certainly significant. You may question 
differences of 10 to 15%, but 50%? Do I exaggerate? Some people would 
hope so. In fact I am scrupulous in my figures and inferred 
conclusions.
At 5.6 the H versus L difference has diminished to (40 lines) 55% to 
72%, Still a considerable difference,

That people perceive Hasselblad pictures as sharper has nothing to do 
with the optical qualities but the film area, as so many 
contributions have discussed and the lower enlargement factor.
BTW: I did not state that every 35mm lens is better than the 4/150. I 
said specifically that the apo 90 was better as shown above. I have 
the highest regards for Zeiss lenses, but their strength is the 
smoothness of rendition of outlines and the beautiful definition of 
fine textures.
I also did not say that Leica pictures are better than Hasselblad 
pictures: I did say that Leica pictures deliver comparable quality 
and sometimes under suitable conditions may challenge 120 format 
pictures up to 12 times enlargement. An enlargement from a Leica 
negative to a format of 12x16inch is a factor of 12, The same print 
for a 120-negative is an enlargement of 5 to 6 times. If under these 
unfavorable conditions a Leica print can be compared favorably to a 
Hasselblad print speaks very well for Leica lenses.


Erwin