Re: [Leica] lens evaluations

["John McLeod" <johnmcleod@worldnet.att.net>]

Erwin,

Thanks for whetting our appetites regarding your findings for the five 50mm
R and M lenses.  As you know, I am particularly curious about the
performance in the center of the field (resolution of fine details and
contrast) of the five lenses, especially the new 50/1.4 R, and await your
final report.  By the way, what is the "zonal" region?  Is this the area
between the center and far corners of the image?

John
- ----------
>From: Erwin Puts <imxputs@knoware.nl>
>To: leica-users@mejac.palo-alto.ca.us
>Subject: [Leica] lens evaluations
>Date: Sun, Aug 23, 1998, 9:16 AM
>

>Recently a long quote by Jim Williams (Contax G fame) hs been circulated on 
>the LUG. I at first resisted temptation to react. Still some comment is 
>appropriate I assume. First of all his text is full of statements, not a 
>single one prooved or explained. He is also demagogially clever ("superb" 
>Zeiss lenses versus "computer designed" Summicrons). It is however not my 
>goal to refute Mr Williams. He seems convinced of his opinion and so be it. 
>At stake is the reputation of Leica or its "reputational myth-making". And 
>the large group of Leica users who "because of their own fixed 
>beliefs in Leica superiority -- certainly weren't about to disabuse the 
>masses of their illusions". 
>So are leica lenses superb or just front runners or me-too products. Were 
>leica lenses unsurpassed in the past or not? 
>From my postings (and test result) you will know that I am not a person to 
>give super high marks to older Leica lensgenerations. But I am also not 
>inclined to give older Zeiss or Japanese very high marks. The Planar 2/50 
>for the Contarex, once described as of unsurpassable optical quality, is 
>very good but not state of the art anymore. And so is the seven element 
>Summicron.  
>Many Leica lenses are excellent and often the number one for its fovcal 
>length and specs. But leica also had and has lesser designs, quite apt for 
>its task, but not state of the art: the 1,4/35 Summilux and the Summicron 2/90.  
>The problem with all these generalisations is this: they assume one fixed 
>evaluation standard along which all lenses can be measured and given a 
>simple merit figure (be it a number, a word or a range of stars).  
>This is quite wrong and even more importantly it misrepresents the reality. 
>You still owe me the Summilux-R report. Why? I have all bench results, 
>hundreds of comparison transparancies and many MTF graphs. So it should be 
>easy to make a comparison and a clear ranking? Ok, let us start: 
>I compared the Summicron-M and R and the Summilux-R (old) and new and the 
>Summilux-M. That gives a bit body to an evaluation and it brings out small 
>differences, which may not be important for a star ranking, but are 
>important for real life shooting.  
>Well overall the Summicron-M is slightly ahead of its R-sibling. At full 
>aperture the M has a bit more contrast and its ability to record extremely 
>fine details with outstanding clarity is greater. Also the performance of 
>the M extends over a larger image circle than does the R, which is a bit 
>weaker in the corners.  
>The Summilux-R (old) is of low contrast and the recording of fine detail in 
>the center is very good, but drops off fairly quick (after an image circle 
>of 6mm radius). Stopping down the quality improves slowly until at f/5,6 to 
>f8,0 where we can find excellent quality. 
>The new Summilux-R has a high contrast at full aperture with fine to very 
>fine detail excellently rendered over the whole image field. Stopping down 
>one stop brings image quality better than its predecessor at f/4,0 and on 
>stopping down image quality rapidly improves to a new optimum level at f/5,6. 
>The Summilux-M is about equal to the new R in the center (6mm radius) but 
>stays behind in the outer regions. Stopping down improves the contrast and 
>the clear rendering of very fine detail. At f/5,6 we have excellent 
>quality. The Summicron-M at the same aperture could be qualified as of 
>exceedingly high imagery. 
>
>Now I do hope that in the context of these descriptions designations like 
>"very fine details" and "outstanding clarity" make sense and can be related 
>to photographic practise and expectations of image quality. To be brave and 
>reckless for once I would rank the Planar 1.4/50 for the Contax RTS as 
>above the old Summilux-R but below the new one.  
>
>Now how should we rank these five lenses based on the text above? 
>Summicron-M is still the best, followed at a little distance by the 
>Summicron-R, which is closely followed by the Summilux-R new. This lens in 
>some important areas inches ahead of the  Summilux-M.  
>The Summilux-R old is a bit lagging in all areas and outdistanced by the 
>new Summilux-R. 
>This would be Ok as far as my *current* set of evaluation criteria will 
>allow. If you put different weightings to the several components of image 
>quality (as defined by me, mind you) the ranking and the evaluation could 
>be different. The clear and contrasty rendition of very fine detail in the 
>zonal region at the wider apertures is for me a very important componant as 
>it will define the capacity  of big enlargements from negatives (or 
>trannies) taken in adverse luminance conditions. Most testers I know of 
>(yes also CdI) are looking for different aspects of image quality. 
>The overall ranking might or might not be the same. But a simple star 
>rating system (the Summicron-M gets 5 stars from CDI, the Summicron-R gets 
>4 and the Summilux-M gets 3) does not give insight into the finer points of 
>the differences in optical performance. It will also not tell you how the 5 
>or 4 or 3 stars have been put together.  
>If we now would try to compare lenses from several reputable companies over 
>long ranges of lenses and over several decades with different and often 
>non-reproducable test paramaters from many different persons who also 
>change their evaluation criteria (or even more worse did not change their 
>criteria) we would be insane. At least I would be insane. 
>
>
>Why then did I start with telling you that I have not yet made my final 
>report. Because I do conduct tests at several distances ( 1 meter, 3 
>meters, 5 meters and 10 meters or infinity). It is quite logical that at 1 
>meter the capacity of rendering fine details is different from the 10 meter 
>distance if you are looking for the *same fine details*!!. At one meter we 
>would need let us say 10 lp/mm of good contrast to record these details. At 
>5 meter we need 50lp/mm to record the same details with the same contrast 
>and clarity. As 50lp/mm represent unbelievably  fine details that can not 
>be seen in a transparancy projected to a 4 meter image and viewed at close 
>range we must carefully reflect how to evaluate performence differences at 
>this demanding level of image quality. Now the 5 lenses mentioned above 
>have different characteristics in this respect and I just need time and 
>some study to phrase my conclusions. 
>
>
>Erwin