p.2 #1 · Zeiss on track with their recent lens designs?
alundeb wrote:
IMHO both the new 35/1.4 and 25/2 are very interesting lenses, as they have integrated both pleasing out of focus rendering and potentially high modulation at all frequencies, but with a few exceptions as to where and when.
p.2 #2 · Zeiss on track with their recent lens designs?
alundeb wrote:
You don't have much experience with modern (roughly the generation having SW Coating, the last few years) Canon L lenses? They have both.
Do they? I guess I've missed the microcontrast part then as I could only see the sharpness.
p.2 #3 · Zeiss on track with their recent lens designs?
Being no scientist, I have no idea what Luka's graphs mean
Perhaps my information is outdated, and modern lenses can in fact combine high resolution with high contrast at medium frequencies (what I believe is called micro contrast).
But to illustrate my point, I would like to compare it to pencil drawing. Using a pencil with a medium sized head will produce very sharp and contrasty images at normal viewing distances. However, if you put your nose in the drawing, you will realize there is no fine detail. Using a very fine head it is possible to draw unbelievably microscopic detail but when you look at normal viewing distances, you will realize the drawings are lacking in contrast and sharpness. Back during Contax and Leica R days, Zeiss decided to draw with a medium size pencil, while Leica opted for the fine pencil, even though according to Erwin Puts, Leica may have decided to follow the Zeiss approach at a later stage since Zeiss seemed to be more successful.
p.2 #4 · Zeiss on track with their recent lens designs?
For Ed:
"Most of the high-speed standard lenses from the sixties were corrected like this at large apertures. At 10lp/mm they had only 60-70% MTF, whereas nowadays 80-90% is usual here.
At the time, one said the lens was ‘optimized for resolution’, which is not
exactly correct, because they simply had a good edge definition, but the resolving power for fine periodic structures was no better than in lenses with a different design.
Incidentally, it is not the case that, when designing a lens, a decision has to be
made between high resolving power and good contrast rendition; both are possible for lenses with good correction. "
p.2 #6 · Zeiss on track with their recent lens designs?
Tariq Gibran wrote:
Technology does not stand still. The upcoming 36MP+ sensors will actually require more resolution, particularly off axis. [snip] This would seem to indicate that lens resolution will need to increase with increasing sensor resolution to give similar effects.
This is exactly what was explained to me by a Zeiss dealer when I noted that the new ZE/ZF lenses are all quite expensive.
The graph shows the MTF (modular transfer function) as a function of spatial resolution. If we look at the lens MTF at 10 lp/mm, we're at 95% while at 160 lp/mm it's below 40%. To use your pencil drawing analogy, the spatial resolution (measured in lp/mm) is the thickness of your pencil while the MTF is the contrast of the pencil against a white paper (i.e how black it is).
A modular transfer function shows how the lens projects a point. It's the point spread function (PSF) expressed as a function of spatial frequency.
The image on the right is the same as on the left but with gaussian blur applied to it. Do you see the drop in contrast?
For all practical purposes MTF is the same thing as micro contrast and that's how the term is correctly used.
Perhaps my information is outdated, and modern lenses can in fact combine high resolution with high contrast at medium frequencies (what I believe is called micro contrast).
Micro contrast is not limited to some specific range of frequencies. You can have high or low contrast at any spatial frequency. A low frequency will almost always have a higher micro contrast than a high frequency. And the dropoff is usually exponential. Resolution is not an independent entity - high micro contrast means high resolution.
It's not a question of outdated information - this applies to all optical elements, including just air.
But to illustrate my point, I would like to compare it to pencil drawing. Using a pencil with a medium sized head will produce very sharp and contrasty images at normal viewing distances. However, if you put your nose in the drawing, you will realize there is no fine detail. Using a very fine head it is possible to draw unbelievably microscopic detail but when you look at normal viewing distances, you will realize the drawings are lacking in contrast and sharpness. Back during Contax and Leica R days, Zeiss decided to draw with a medium size pencil, while Leica opted for the fine pencil, even though according to Erwin Puts, Leica may have decided to follow the Zeiss approach at a later stage since Zeiss seemed to be more successful. ...Show more →
The error here is that you are thinking that the pencils are the same colors. When it comes to lenses, the thick pencil is nearly 100% black while the finest pencil is perhaps 10% gray.
As for Leica R, you are mistaken. In terms of optical performance, resolution or otherwise most of them are just shit. They have a lovely drawing style but to get there they sacrificed any semblance of performance. There are exceptions such as the 60 Macro and a bunch of the tele lenses, but most of the prominent ones such as the 35 Lux-R and the 50 Lux-R are a joke when it comes to resolving power. This was of course done on purpose to get a softer rendering style and a price Leica was willing to pay.
Top graphs, 35 Summilux-R, bottom graphs 35 Summilux-M ASPH:
A general rule, if you wish to state one is that you can't have low micro contrast and high resolving power. Resolution and micro contrast always go together, simple because they are actually the same thing.
p.2 #9 · Zeiss on track with their recent lens designs?
Thanks for taking the time to explain this Luka. Back in the early 90s when I bought my first Zeiss lens, that was the common belief at that time. Now I can see it was a misconception, and the excerpt from Dr. Nasse's essay quoted by Philip insinuates that he's aware of this misconception and in fact is refuting it.
p.2 #10 · Zeiss on track with their recent lens designs?
Keith B. wrote:
I've never seen the term "micro contrast" mentioned by any designer, or expert in the field of lens design. Only on amateur PP forums.
For this statement to be meaningful to anyone but you, I guess you need to tell us how often you have partaken in a conversation between optical designers and experts in the field of lens design? A simple integer number will suffice. You should probably also state more bluntly what conclusion you make from this.
p.2 #11 · Zeiss on track with their recent lens designs?
denoir wrote:
As for Leica R, you are mistaken. In terms of optical performance, resolution or otherwise most of them are just shit. They have a lovely drawing style but to get there they sacrificed any semblance of performance. There are exceptions such as the 60 Macro and a bunch of the tele lenses...
There are also some other good lenses. The 15/2.8, 19/2.8 II, 28/2.8 II and latest 50 Lux are all meant to be quite strong. The 19 is not as sharp as the 21 Distagon, but is still very good. I am not aware of a better 15mm or 28mm SLR lens than the above two, and the 50 Lux approaches the 50 Lux-M ASPH. The 90AA is of course also brilliant, as is the 100/2.8 Macro. And then there are the teles you mention.
p.2 #12 · Zeiss on track with their recent lens designs?
carstenw wrote:
There are also some other good lenses. The 15/2.8, 19/2.8 II, 28/2.8 II and latest 50 Lux are all meant to be quite strong. The 19 is not as sharp as the 21 Distagon, but is still very good. I am not aware of a better 15mm or 28mm SLR lens than the above two, and the 50 Lux approaches the 50 Lux-M ASPH. The 90AA is of course also brilliant, as is the 100/2.8 Macro. And then there are the teles you mention.
I'd like to use these lenses, but I don't feel like fumbling around with stop down metering. If Leica were to build these lenses in Nikon or Canon mount, I'd try the 28/2.8. Until they do I'll continue to enjoy the impressive 3D images I get from my ZF 28/2 and ZF 35/2. Believe I'll be picking up the ZF 25/2.8 as well.
p.2 #13 · Zeiss on track with their recent lens designs?
Keith B. wrote:
I've never seen the term "micro contrast" mentioned by any designer, or expert in the field of lens design. Only on amateur PP forums.
How about the Zeiss head of optical design, Hubert Nasse:
But what does ‘contrast rendition’ actually mean? We must not forget that when we talk about ‘contrast’ we always mean micro contrast, i.e. structures, which we can just about see or just cannot see with the naked eye, for example on a slide. But if we photograph a chessboard, for example, so that it fills the format, the contrast between the black and the white squares has nothing to do with this.
p.2 #14 · Zeiss on track with their recent lens designs?
carstenw wrote:
There are also some other good lenses. The 15/2.8, 19/2.8 II, 28/2.8 II and latest 50 Lux are all meant to be quite strong. The 19 is not as sharp as the 21 Distagon, but is still very good. I am not aware of a better 15mm or 28mm SLR lens than the above two, and the 50 Lux approaches the 50 Lux-M ASPH. The 90AA is of course also brilliant, as is the 100/2.8 Macro. And then there are the teles you mention.
Heh, I was expecting this. Yes, my statement about R was a bit of a hyperbole and an unfair generalization
p.2 #15 · Zeiss on track with their recent lens designs?
"most of them are just shit."...that's an overly harsh judgment by any stretch of the imagination.
Most lenses in all lineups are not top drawer, within the narrow confines of absolute excellence - le mieux est l'ennemi du bien.
Leica did a mighty job of their great telephotos, the ground-breaking 35-70mm f2.8, their heavy but spectacular telephoto zooms, their 100mm and 60mm macros, their short telephotos, the 90mm AA especially, the 28/2.8 E55. Quite a list, compared with anyone else's SLR output. We would be much impoverished if they did not exist..
While not to everyone's taste, many of the short to normal R lenses trade off all-of-frame excellence for very high central impact, and ultra smooth gradients.
This is the result of a design goal obviously, and seen in these terms, they were and are very successful. Mike Johnston (of the Online Photographer website) is on record as believing the 35mm Summicron R was his favourite lens. Here is one for interested parties:
The E55 Summicron R put 80% on the image centre for the 40 lpmm at f4-5.6, and shares the optical formula with its M counterpart, another example.
Carsten mentions the 19mm, from its MTF it is no Distagon 21mm level performer, for what that lens can do. It has other attributes I am sure. The takeaway message is: know what lens suits your intended purpose! Especially with Leica...
carlitos, check out the new Zeiss 25 f2. Close to the 21mm except in extreme corners and may be good enough there also, at mid apertures.
In the end, the proof of the pudding is in the image - nothing else really matters, right? All these lenses are well represented in the Leica R image thread...and many or most images are quite a considerable distance from having been made with 'shit' lenses.
p.2 #16 · Zeiss on track with their recent lens designs?
philip_pj wrote:
The E55 Summicron R put 80% on the image centre for the 40 lpmm at f4-5.6, and shares the optical formula with its M counterpart, another example.
this statement absolutely cannot be true. the m counterpart to the m 35mm cron was minuscule in dimension. if you put that design in an slr lens the front element would reside where the mirror goes.
if you meant the 50mm cron, they are very similar (but what 50mm non macros aren't), but again some adjustment had to be made to account for the mirror. you can see the differences in mtfs as well.
Dec 04, 2011 at 12:46 AM
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p.2 #17 · Zeiss on track with their recent lens designs?
I mostly use the ZE line. And I'm very happy with Zeiss recent lens designs for ZE. But I wouldn't mind a couple of new lenses that are longer than 50mm in the future
p.2 #19 · Zeiss on track with their recent lens designs?
bluetsunami wrote:
Never understood why people need to make silly snipes like this, does the term really anger you? Fortunately this whole discussion is above this.
