[Leica] Super-achromat

[Erwin Puts <imxputs@knoware.nl>]

Mark Rabiner referred to the Zeiss Super-Achromat and  said that Apo 
is not a hype. I did not say that apochromatic correction is a hype. 
When the apochromatic error is indeed reduced in a design, lens 
quality improves and the level of improvement depends on many things. 
I noted that press and  PR people have used the designation 'Apo" 
without inquiring after the optical facts behind the concept and so 
made it a mythical and mystical property of lenses. In my view it 
makes no sense to copy and rephrase pieces of information if you are 
not able to understand and explain what it is that is being 
discussed. On this list we often find citations from and references 
to all kinds of sources, from "anonymous,but reliable individuals", 
leaflets issued by manufacturers, magazine articles, and named 
individuals. This recycling of information presents a major problem 
as it generates much noise. It is part of human nature that we tend 
to believe the story we hear most often from several sources. But 
often a careful search for sources will tell you that often people 
are just playing copycat. Fact-based independent research is really a 
scarce commodity, and has always been. Some examples. About B&W 
processing much is being discussed and proposed and presented as 
fact. Well most of this cannot stand the test of a scientific 
analysis. The only person who ever conducted a large scale scientific 
research project on all aspects of B&W processing is Richard Henry in 
his book:"Controls in Black and White Photography". This is truly 
research and factfinding of the highest level, and from my mouth that 
is praise indeed. But I never have seen any reference to this book. 
What I do see is that much of the information about B&WPprocessing 
contradicts his findings. Guess who I believe.
This book is a model of carefully conducted research, theory exposure 
and  explanation. It should be inspiration for anyone who would like 
to go beyond the mere personal experience.
The Nikon-Leica controversy as triggered by the Duncan story. 
Avoiding the political and sensitive issues, the basic question is: 
were the Nikon lenses then better (please define"better") than 
contemporary lenses from Leica or Zeiss. Much discussion followed, 
none conclusive. The simple act of testing these lenses would have 
solved the issue. So that is what I am going to do.  Next week there 
is a major Nikon gathering in Rotterdam (Tom A will be there too) and 
I will ask some collectors to lend me the DDD lenses. I will then 
test them according to my normal procedure and that at least would 
give me any reliable info.
Last example: the wellknown and often discussed  issue of the 
plasticity and 3-D impression of Leica lenses.  A Leica broschure 
from 1936 on page 8 notes this effect when discussing the Summar and 
from then on we can trace this statement through literature, 
including many of the books about Leica. Any facts or pictorial 
demonstrations are not available. Again I am conducting a series of 
tests to see what this statement is worth. The broschures can be 
found on my CD, btw.
All these tests are time consuming and laborious and maybe it is more 
fun just to continue with the more pleasant  part of photographic 
lore.
Now at last: a super-achromat is corrected for more than four 
wavelengths, (black is not a color ar a wavelength):
(from blue to infrared) 435 nanometer, 514nm, 643nm, 714nm and 900nm.
The normal panfilm has a sensitivity range from 350 to 680, IR films 
go from 350 to 900.

Erwin