cogitech wrote:
I also think, as opposed to Lotus, that it is very possible for a lens to enhance the macro-contrast of a scene. We all know what a polarizer can do to light, so why is is so difficult to believe that advanced coatings could alter light in dramatic ways?
A polarizer filters out light. Are you suggesting that Zeiss (or whomever) is designing lenses to filter out light, and reduce the light transmitted by the lens? That is hardly likely for any camera lens designer to do or even want to do. They want to maximize light transmission. Further, the whole idea of lens coatings is to transmit as much light as possible through the lens, and to reduce the amount of lens reflected off of lens surfaces. Having the coatings filter out some light is contrary to the purpose. And if they could do this, why wouldn't they say design them to filter out UV, for example? Because it is not the point, it is not the reason why coating are applied, and it would defeat the purpose.
I will note that the MTF's (which represent contrast) are out of 100%, and no one reaches 100%. They are essentially a measure of how much contrast is lost. All lenses (passive camera lenses, that is) lose some amount of contrast (and do so more in some areas than others). Even Zeiss lenses. There are none that create, enhance or amplify contrast.
Here is an interesting article on the different traditonal approaches that Leica, Minolta and Zeiss have taken in designing their lenses, particularly with regard to coatings and their affect on color balance and contrast.
Lotusm50 wrote:
A polarizer filters out light. Are you suggesting that Zeiss (or whomever) is designing lenses to filter out light, and reduce the light transmitted by the lens? That is hardly likely for any camera lens designer to do or even want to do. They want to maximize light transmission. Further, the whole idea of lens coatings is to transmit as much light as possible through the lens, and to reduce the amount of lens reflected off of lens surfaces. Having the coatings filter out some light is contrary to the purpose. And if they could do this, why wouldn't they say design them to filter out UV, for example? Because it is not the point, it is not the reason why coating are applied, and it would defeat the purpose.
I will note that the MTF's (which represent contrast) are out of 100%, and no one reaches 100%. They are essentially a measure of how much contrast is lost. All lenses (passive camera lenses, that is) lose some amount of contrast (and do so more in some areas than others). Even Zeiss lenses. There are none that create, enhance or amplify contrast. ...Show more →
I'm merely suggesting that the coatings may have properties that we are unaware of. I'm suggesting this because I have observed what I (subjectively) feel is unnatural amounts of macro-contrast in certain lenses. Some of them were Zeiss lenses, others from Canon and even Tamron. It isn't as if one whole series of lenses displays this property invariably. I love the moderate contrast of my 135 Sonnar, for instance.
Tariq Gibran wrote:
Wow, Great finding! I think this Nokton has moved to my "must have" list based on this thread.
Upon further investigation, I think I missed the mark slightly.
The Rokkor 1.2 is a 7 elements in 5 groups design, whereas the Nokton is a 7elements in 6 groups design. Obviously there is the speed difference as well, but I was struck my the obvious similarities of the design, and also by the "signature" of the Nokton. It does remind me very much of the Rokkor.
ISO1600 wrote:
LotusM50, you're the most subjectively opinionated person i've ever come across. It doesn't matter if 9,000 people agree on one thing, you can write for days as to why they're wrong.
I see very little in Lotus's post that could be construed as opinion. He is exceptionally informative and brave enough to challenge accepted wisdom on this forum. He frequently raises very interesting questions, for example, whether a lens could add contrast, or only attenuate it. You don't have to agree with what he says to benefit from it.
I think it is necessary to distinguish between micro-contrast (AKA local contrast) and macro-contrast. Obviously micro-contrast is inherently tied to the apparent resolution of a lens. Macro-contrast, not so much.
The thing is, there are lenses that show excellent ability to resolve, but at the same time maintain a moderate to low level of macro-contrast.
Any of us who tend to dislike "uber contrast" are likely in agreement that we are speaking about "too much macro-contrast."
I also think, as opposed to Lotus, that it is very possible for a lens to enhance the macro-contrast of a scene. We all know what a polarizer can do to light, so why is is so difficult to believe that advanced coatings could alter light in dramatic ways?
The reason I feel this way is because, when I shoot a photo, I use my eyes to look at the scene as much as I use the camera. When I use two different lenses for the same scene, I can see that the lenses with moderate contrast tend to render the scene more "realistically" according to the way I saw the scene with my naked eye. Lenses with over-the-top macro-contrast tend to be almost artificially contrasty, and not true to the scene. This is, of course, a very subjective point. Other, less subjective, reasons why I prefer moderate contrast lenses; 1) it is easier to add contrast in PP than to reduce it (it is quite difficult to extract detail from pure black) 2) Extreme macro-contrast pushes our digital sensors to the limits of their dynamic range, and often beyond (I find it much easier to stretch a curve than compress one that has dropped off either end, or both)....Show more →
Good point to be sure.. Probably why I prefer the images from my Leica R lenses over most others I own or use. Thanks for pointing this out. What, in your opinion, affects the degree of microcontrast that a lens shows?
Not sure, Woody. I'd guess that both the optical formula and the composition of the elements would have the greatest effect on resolution and micro-contrast. We know that flourite and/or radioactive substances (among others) can enhance a lens's ability to refract, disperse, etc. light. Higher end lenses typically incorporate "ED", "LD", etc. elements, not to mention APO and aspherical elements and this results in higher resolution and reduction of aberrations. I think lenses like this would resolve exactly the same amount of detail with single coatings. Macro-contrast would be significantly reduced, but micro-contrast would remain.
Both Rokkor and Nokton are based on double-gaussian design which is considered the best optical formula to reach f/1.0 level. However, they can still differ greatly in performance when the designer applied different parameter values.
Yes, both the Rokkor and Nokton are based on double-gaussian design, just like the Planar (and virtually all 50mm standard lenses).The basic double-gaussian design as applied to all these camera lenses was, of course developed by Paul Rudolph of the Carl Zeiss company back in 1896.
cogitech wrote:
..........................................Higher end lenses typically incorporate "ED", "LD", etc. elements, not to mention APO and aspherical elements and this results in higher resolution and reduction of aberrations................................................
An element by itself cannot be APO (Apochromatic) unless it is a first surface mirror. For refracting optics this quality is achieved by designs using two or more refracting lens elements of different optical properties to oppose or cancel the chromatic aberration introduced by the other element(s).
