Archived posting to the Leica Users Group, 1997/07/20

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Subject: Re: 35/2 ASPH.lens - thick element. (2)
From: Erwin Puts <imxputs@knoware.nl>
Date: Sun, 20 Jul 97 11:28:04 +0200

Yes,there are differences. Look at the older designs and you see 
relatively simple shapes. Now, and the 24mm is a good example, you see 
complex shapes. You also might notice that the frequency of using these 
lenses increases. (see the Summar 3,2/32 in the Leica compact). Two 
reasons: one is hat the use of thick and relatively soft glass now is 
possible because the time lag between polishing and coating is only a 
couple of hours. Tight production logistics are  imperative 
here.Otherwise the polished surface would already be deteriorating. The 
other reason is that the availability of optical glass shrinks. Exotic 
glasses are scrapped from the catalogues because the demand is too low. 
Then the designer has to fall back on still available glasses and has to 
use unusual techniques to guarantee the desired performances. In this 
respect I think Leica and Zeiss are leading in the world. 
If the efforts and costs are worth it, is a matter of opinion and a 
discerning eye and technique. Many postings here have noted that in most 
circumstances you can not or hardly see any performance difference 
between the good Nikon and Canon and Minolta etc lenses. 
The classical 80:20 rule works here too. To notice the last 20% 
performance difference you have to put 80% of your effort into this 
task.On the oher hand: if you only put 20% of your effort in the optical 
performance you get 80% of the potential performance and on that level 
most topclass lenses are equal. This could explain why most test results 
do no note the differences that are still here. 
Erwin Puts