Roger Hicks
Veteran
Thanks very much indeed for posting the link; as I said in an earlier article, I found a reference to the article, but I couldn't get into it.
Now I've read the article, although I found it fascinating and full of insights, I am not entirely convinced of the author's understanding of lens design. This may be for one of three reasons. First, I know so much less than he does, that I cannot understand him. Second, I know a tiny bit more. Third, that he did not always express himself outstandingly well.
To the best of my recollection, for example, computer-aided lens design (which is what I assume he means by 'modeling') was in use at Imperial College in London in the early-to-mid 1950s (from conversations with Sir Kenneth Corfield), and there are also two generations of computer-aided design: ray-tracing and wave-front.
Also, a reference to an 'apo correction element' strikes me as somewhat simplistic, as it implies you can stick in an extra glass to get apochromatic correction, whereas, of course, apo correction is a function of the whole design -- and apochromatism may be cubic (the norm, three wavelengths) or quartic (four ravelengths, apparently not unknown).
Although I think I have been introduced to Herr Karbe, I have never talked to him at any length, but I have talked to Dr. Nasse at Zeiss at considerable length, and he is something of an expert too. Not knowing Herr Karbe, I cannot judge who knows more -- but both are so staggeringly knowledgeable that few could say, if indeed the question means anything.
In other words, I don't think that the new 35mm lenses do anything to the S2 designs, though both owe a lot to the reorganization and of course the two new Summiluxes feed off one another -- which is also why there isn't a 28 Summilux in that series.
Cheers,
Roger
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Freakscene
Obscure member
Freakscene
Obscure member
Third, that he did not always express himself outstandingly well.
I agree that it is very poorly written. It reads like an advertorial.
Also, a reference to an 'apo correction element' strikes me as somewhat simplistic, as it implies you can stick in an extra glass to get apochromatic correction, whereas, of course, apo correction is a function of the whole design -- and apochromatism may be cubic (the norm, three wavelengths) or quartic (four ravelengths, apparently not unknown).
All manufacturers determine their own criteria for describing a lens as APO. Leica have use the term 'APO' only as cryptically as anyone else. Measurements show that the lenses Leica calls APO are very well corrected and out to 900 nm or beyond. At Leica, just as everywhere, APO means 'well enough corrected that we will call it APO' and in recent lenses may reflect that special glass elements are used (these do aid in correcting chromatic aberrations) a bit like a Nikon call a lens 'ED'.
There are no APO lenses currently available for cameras. There used to be a couple that were better corrected than almost all available today. Process lenses and some enlarging lenses beat all camera lenses in this regard, but the reasons for most of those lenses being designed and built now don't exist. Technology moves on and correction for colour shifts is not everything. These new Leica lenses are arguably the best wide angle lenses ever made for 35mm photography.
And there may be a 28/1.4 on the way.
Marty
I agree that it is very poorly written. It reads like an advertorial.
Also, a reference to an 'apo correction element' strikes me as somewhat simplistic, as it implies you can stick in an extra glass to get apochromatic correction, whereas, of course, apo correction is a function of the whole design -- and apochromatism may be cubic (the norm, three wavelengths) or quartic (four ravelengths, apparently not unknown).
All manufacturers determine their own criteria for describing a lens as APO. Leica have use the term 'APO' only as cryptically as anyone else. Measurements show that the lenses Leica calls APO are very well corrected and out to 900 nm or beyond. At Leica, just as everywhere, APO means 'well enough corrected that we will call it APO' and in recent lenses may reflect that special glass elements are used (these do aid in correcting chromatic aberrations) a bit like a Nikon call a lens 'ED'.
There are no APO lenses currently available for cameras. There used to be a couple that were better corrected than almost all available today. Process lenses and some enlarging lenses beat all camera lenses in this regard, but the reasons for most of those lenses being designed and built now don't exist. Technology moves on and correction for colour shifts is not everything. These new Leica lenses are arguably the best wide angle lenses ever made for 35mm photography.
And there may be a 28/1.4 on the way.
Marty
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