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Archive 2013 · Micro contrast ?
  
 
kwalsh
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p.2 #1 · Micro contrast ?


theSuede wrote:
Sharpening like normal unsharp mask in photoshop, on normal sRGB or Adobe RGB images, brightens opposite edges to increase the perceptual sharpness by increasing edge contrast, but is often feels less "natural". And it definitely isn't "natural".


Good post, thank you!

On this one point, however, I'll be cautious. As far as photographers go they really care about the entire imaging system, not just the lens - though sometimes they don't know it. Good example would be halation glowing in film emulsion. It certainly isn't "natural" in the sense of a lens, but like all things once viewers were exposed to it for decades it has become "natural" to many people. Every few months you'll see digital photographers posting old images and asking what classic lens they should use to get this effect not realizing it has nothing to do with the lens.

So in this case it is worth noting that standard USM is analogous to what happens when developing film. The dark gets darker AND the light gets lighter because of developer diffusion across the edge. And experienced processors controlled this intentionally through different developer dilutions and agitation schemes. Since most of us have been exposed to such images for much of our lives it becomes as "natural" as film grain and lens flare despite really being a "flaw".

Anyway, a bit off topic, but I thought it worth mentioning as these "What is 3D" threads seem to come up with great frequency. In each one there is an interesting technical discussion. But at the same time you have to remember the perception and the trained expectation of the viewer can play as large a role as any optical analysis might.



Apr 26, 2013 at 06:52 PM
sebboh
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p.2 #2 · Micro contrast ?


kwalsh wrote:
Anyway, a bit off topic, but I thought it worth mentioning as these "What is 3D" threads seem to come up with great frequency. In each one there is an interesting technical discussion. But at the same time you have to remember the perception and the trained expectation of the viewer can play as large a role as any optical analysis might.


indeed, looking for 3d in images makes it much easier to find than if you look at images never thinking about the possibility of them having a 3d look.

with regard to USM not being natural, it depends on what you mean by natural. it turns out our brain does some similar tricks on the neural level to pull out object boundaries and that USM works well for highlighting edges in part because of the way lower level visual receptive fields are organized.



Apr 26, 2013 at 07:09 PM
RustyBug
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p.2 #3 · Micro contrast ?


Yup ... and some folks just simply have better/worse depth perception capabilities. I would imagine the brain functioning that allows for picking up on the cues that suggest "depth" in real world 3D have a similar role in associating those (illusional) cues in a 2D realm to suggest "depth" as well.

It would be interesting to create subgroups of those who can see the "3D" in 2D images and those who can't compared to their general depth perception abilities. I would not be surprised to see a correlation.



Apr 26, 2013 at 07:56 PM
wfrank
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p.2 #4 · Micro contrast ?


theSuede wrote:
Actually I'd want to correct the middle part of this statement, since it affects all sharpening and contrast post processing...
Black does not "bleed". It can only be bled into, since there's no such thing as "negative light" - at least not until you go into deep physics that have no real meaning to a photographer (or approximately 6,499,999,900 out of the 6.5 billion people living on this earth either for this matter... ) - You can however have phase cancellations, and this is what gives the black rings in between the bright rings in a diffraction circles.

Points where light
...Show more

Joakim, leaving micro contrast behind would there by any chance be a relayable scientific viewpoint on the topic of 3D? Myth or reality or something simply in the eye of the beholder. Obviously a dry standpoint is that 3D projected on a flat service is baloney but perception of depth in an image is not. I admit that I am a believer. Hopefully quite relaxed though






Apr 26, 2013 at 08:05 PM
redisburning
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p.2 #5 · Micro contrast ?


RustyBug wrote:
It would be interesting to create subgroups of those who can see the "3D" in 2D images and those who can't compared to their general depth perception abilities. I would not be surprised to see a correlation.


that would be interesting to know.

I would also like to know how this perception applies to stereoscopic "3D" like they use in the movies? I see the effect fairly frequently, especially in side lit large format photographs with modern lenses, and that **** they use in the movies looks unbelievably fake to me.

wfrank wrote:
Obviously a dry standpoint is that 3D projected on a flat service is baloney but perception of depth in an image is not.


people have understood depth in 2-dimensional art for thousands of years. warm colors come forward while cool colors recede, shadows can give impression, objects can overlap and scale all contribute, along with other factors, to a perception of depth in an image.

people dont think of it in terms of the brain. 3-dimensionality comes from the brain. 2 2-d images do not magically make a 3-d image. the brain has to put it together, and it uses all sorts of tricks to construct our vision. we are not computers.



Apr 26, 2013 at 08:15 PM
RustyBug
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p.2 #6 · Micro contrast ?


Trompe-l'il is French for deceive the eye ...

Notice the hinges on the left door frame and the strike plate on the right. This door is closed ... i.e. a picture of a picture.

Both the center portion and the edges lie in the same plane, but because of the levels of acutance variance involved, we perceive them to be in different planes. Lenses that have very high levels of microcontrast in (say the central) an area of the image, and alternatively lower areas of microcontrast emulate the physiological expectation that objects @ different distances (i.e. different planes) will also have different levels of acutance.

The normal dof aspect of the various distances involved is perceived, well normally. With a lens design that intentionally has an ultra high microcontrast region in the center (arbitrarily say 8mm-10mm) of the frame and then significantly less microcontrast in the edges (say 14mm-20mm), a near distance subject placed in the higher microcontrast region of the frame will seemingly "pop" out more due to the variance ... particularly if we have "space" in the 11mm-13mm range. Kinda like floating a frame on the wall or a shadow box (if you will) to create some perceptual differences.

The combination of the normal dof acutance variance from the focal plane, combined with a strategically designed placement of additional variance can create an illusion of acutance variance even greater than we are accustomed to seeing. This acutance variance gives us the illusion of depth. In that manner, acutance variance enhancement in pp can emulate/enhance that "feeling" of 3D-ishness also.

Areas of rapid transition in compared with areas of slower transitions are suggestive of being in a different plane. Relative fg/subject/bg distances involved, in conjunction with coordinated placement with lens design can render a heightened illusion of objects in different planes based on acutance variance, in addition to the other visual cues that are suggestive of such plane differential.

Subtle, maybe. But when combined with other cues that our brains perceive as indicative of distance indicators, the "3D-ishness" effect can be enhanced by lens design.

BTW, (conversely) some lenses always produce images that look very FLAT ... yet we rarely debate/discuss the influence of lens design as being a salient attribute for why an image looks flat, it is largely assumed as a given. Whether a painting, drawing or photograph (2D), the placement and utilization of visual cues (acutance, scale, values, color, etc) have impact on how much "depth" we may perceive (i.e. illusion). The better the cues are aligned, the better the illusion.

HTH









http://www.couturedeco.com/728-bathroom-3-trompe-l-oeil.html




Apr 26, 2013 at 09:33 PM
theSuede
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p.2 #7 · Micro contrast ?


I would certainly think that 3D perception in a 2D plane image is correlated somehow to "real" 3D perception in individuals.

But I do also believe that the correlation does not necessarily have to be positive, i.e that more of one automatically gives more of the other... Depending on the subject's personal interpretations it may even be the opposite? I'm not even nearly enough deep into psychovisual spatial awareness to give a good answer on that - if a conclusive answer can even exist.

I do know however in subjects that have been either blind since birth, or have had their vision physically impaired down to close-to-blind for very long periods of time - a decade of years or more - and then get their vision restored do not automatically take depth cues from visual shape or visual cues. They haven't yet learned to rely on eye-lens-focus and stereo sight triangulation to get relative depth - this is very obvious if you make them wear a headset that blocks all reverberant audio support information, something blind people are very dependent on.

Visual depth cues is something you train, teach yourself to do. Actually, you can't even distinguish a square shape from a ball in a cognitive sense before learning / relearning to interpret the visual stimuli - which of course makes estimating spatial distances without focal or stereo-triangulation even harder - unless you train the ability.

It's very hard to do these kind of studies in "normal" humans, since the main part of the learning process occurs in infancy. This is before the child has enough linguistic ability (or even a cognitive logic that we can interpret from second hand cues!) to convey the learning process to us... And this means that we're basically guessing right now

The human brain - as we are born - is prepared for learning how to react to and interpret any of our stimuli faculties. It is not in any way pre-programmed to any specific interpretation. The interpretations often follow some general outlines shared by most humans - but this has quite a lot of flexibility. Quite a lot of people are even either bordering on synesthetic, or ARE clinically synesthetic - without realizing it themselves.

I would guess you at least need some ability to empathize synesthesia (if you don't have the clinical "ability") to get a true, cognitive 3D impression from a flat object.



Apr 28, 2013 at 10:06 AM
Steve Spencer
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p.2 #8 · Micro contrast ?


theSuede wrote:
It's very hard to do these kind of studies in "normal" humans, since the main part of the learning process occurs in infancy. This is before the child has enough linguistic ability (or even a cognitive logic that we can interpret from second hand cues!) to convey the learning process to us... And this means that we're basically guessing right now

The human brain - as we are born - is prepared for learning how to react to and interpret any of our stimuli faculties. It is not in any way pre-programmed to any specific interpretation. The interpretations often follow
...Show more

Actually it isn't that hard to do these kinds of studies with infants (even newborns) and they are done all the time. You can infer a lot about what even babies a few weeks old process by the way they suck on a pacifier. From this research it is also clear that newborns are pre-programmed in a very specific way--they are pre-programmed for social interaction. Their vision is best from 12 to 18 inches (just the distance to their mothers face when breast feeding). They perceive faces much better than other stimuli, etc. None of this sheds much light on 3D perception, but newborns definitely aren't a blank slate in terms of what they are they process and neither are adults. There is a pretty large literature on 3D perception, but as far as I know none of it really gets at the issues we discuss around here. It could, however, if people thought it was interesting enough to do the studies.



Apr 28, 2013 at 11:17 AM
RustyBug
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p.2 #9 · Micro contrast ?


I seem to recall a study done with infants on a glass table crawling toward their mothers and the varying results @ how the infants perceived the height differential once they reached the edge of the table ... some would stop at the edge, while others would just keep going.

Similarly, most of us have probably seen other optical illusions where we've "seen it" and some of our friends/classmates never did. The point being that while there are variances in micro-contrast, transition rates, subject distances/spatial relationships, etc. that contribute to the cues involved with perception, there also exists the individual's perceptive abilities regarding such visual cues.

In a linguistic corollary, there may be a multitude of dialects for a given language, yet I may not be able to distinguish the subtle cues that distinguish one from another. Just because I can't distinguish the difference in the cues presented ... doesn't mean the differences/cues aren't in existence, just that I can't detect them. In that regard, some viewers pick up on the visual spatial relationship cues more readily, while others do not.

Not much different than one person walking by a painting and going "Wow, that looks so lifelike." and the person standing next to them, going "Huh? It just looks like a painting to me."



Apr 28, 2013 at 03:30 PM
 

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philip_pj
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p.2 #10 · Micro contrast ?


I have to say I feel life experience has a lot to do with it. Even genetics, as men have better tunnel vision whereas women see a wider angle of view. Australian indigenes have fabulous distant vision, they live in a flat land. Singaporean schoolchildren have very high rates of eyeglass adoption, greatly increased since the high rise boom, maybe from games and gadgets too.

Vision might be a use it or lose it deal. If you do activities which punish you heavily (as in injury and death) for not having excellent depth perception, it might have an learning impact over someone who spent 20 years working on a computer tan.

The processing is going to happen in the brain, and that organ is a magnificent learning organism but it needs the opportunity and context. Vision is active and restless, many with poor vision stare at objects. Fine vision is a huge part of sporting prowess.

How this might pan out is if a person walks/travels through a terrain for a decade or two they are more (much more) familiar with the subtleties of how things look at varying distances, how objects are shaped, what they should look like, the subtleties of tonal variation in different light.

So it may be that some viewers of deep images have no/little prior expertise in picking up visual cues outside an enclosed city environment, and perhaps that is why they 'just don't see it'. Much of photography now happens in front of a computer, augmented by solid time spent in showrooms, and the natural world is alien to many people these days.



Apr 28, 2013 at 11:28 PM
kezeka
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p.2 #11 · Micro contrast ?


philip_pj wrote:
I have to say I feel life experience has a lot to do with it. Even genetics, as men have better tunnel vision whereas women see a wider angle of view. Australian indigenes have fabulous distant vision, they live in a flat land. Singaporean schoolchildren have very high rates of eyeglass adoption, greatly increased since the high rise boom, maybe from games and gadgets too.

Vision might be a use it or lose it deal. If you do activities which punish you heavily (as in injury and death) for not having excellent depth perception, it might have an learning impact over
...Show more


The brain processes the signals sent by the retina. Unfortunately for your argument, the photoreceptors (cones and rods) nor the occipital lobe are going to focus an image. Focusing an image (near and distant vision) is done by modifying the elasticity of the ocular lens via tension and relaxation of the zonular fibers and diameter of the pupil (controlled by the relaxation and tension of the iris). The reason for vision abnormalities between different people is variance in the development of the lens and cornea. The total power in diopters of the human eye (lens + cornea) is around 60, the lens handles 20 diopters and the cornea handles about 40. There are relatively minor errors in production of the cornea and lens that can change the power of the cornea and/or lens that typically are less than 10 diopters within 2 standard deviations of the average (95% of the population) - which means that most people don't have within a 1/6 or 16% deviation from the norm - not that big a deal numerically BUT this is a huge deal with something as important as vision which lead many people to wear glasses or contacts to correct. Correcting the actual diopter power of the cornea is done using LASIK.

But that doesn't yet answer why exactly your comment is wrong. "use it or lose it" was a precursor theory to the theory of evolution. Obviously, it didn't stick around for too long. I would postulate that grand sweeping statements regarding populations such as the Australian tribes vs the people of Singapore be reduced down to theories on evolution. People who have poor vision in an Australian tribe without access to glasses or contacts are much less likely (historically - I don't know about now) to have survived an attack/raid/assault on a wild animal/avoiding a deadly snake and therefore less likely to reproduce. In the long run, less people were probably going to get inheritable defects in vision from their parents and therefore the fitness (or ability of the tribes-people to survive) was increased by reproduction favoring those who could see well at a distance - making that trait more prominent. In Singapore, a large city, people had access to glasses so vision wasn't as important a determinant of someone's fitness and therefore crappy genetic code that could impact vision was more likely to be passed down.

I apologize for the aside from what constitutes '3D' or 'micro contrast' but I felt it was important to dispute that last comment considering my background in science.



Apr 29, 2013 at 12:09 AM
philip_pj
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p.2 #12 · Micro contrast ?


No need to apologize for your beliefs, kezeka, we are an open-minded lot in general. I think it best to not enter the Lamarckian/Darwinian minefield (which you raised rather than I, in your simplistic summation), we have plenty of our own issues with this interesting cogitive subject. My comments relate to 'within lifetime' individual experiences, not transmitted characteristics in any case.

Science of course should evolve, as 'the science is never settled' - and be responsive to new information in light of prevailing theories and contexts, yet so often it is captured by ideologues and zealots of the most extreme and totalitarian nature - so forgive me if appeals to credentialism and authority carry little weight.

I could point you to Karl Popper and Arthur Koestler for more on this under-examined subject. As Marshall McLuhan was fond of saying: 'We (humans) are suckers for a hard sell.' And there is never a shortage of those wearing the cloak of the scientific method who are little more than intellectual propagandists defending crumbling citadels of scientific faiths.

BTW, I don't class observations as an 'argument', though you may if you need to, for your purposes.



Apr 29, 2013 at 04:36 AM
carstenw
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p.2 #13 · Micro contrast ?


kezeka wrote:
Correcting the actual diopter power of the cornea is done using LASIK.


LASIK is only one possible procedure, and not necessarily the best one. There was a thread here about this at some point.



Apr 29, 2013 at 04:38 AM
RustyBug
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p.2 #14 · Micro contrast ?


Kezeka, I think you may have misunderstood what philip (my take on his post) was saying. I think he was referring more to environmental practical/proficient utilization rather than evolutionary genetics.

For example, when a person loses their vision, they tend to adapt by an increase in utilization and acuity of their other senses (i.e. touch, hearing, smell & taste). The converse to this is that the same person before losing their sight would not have been utilizing their non-visual senses to the degree that they could have refined them ... else, there would not have been room for improvement.

My take on what Philip was saying is that "use it or lose it" is a condition of individual utilization. I used to be able to "feel" the diff @ .001" vs. .002" as a matter of performing extensive precision alignments on pumps/motors. Of course, I used tools to confirm such detectability, but that was decades ago and my tactile sensitivity is no longer at that level. The same can be said for musicians to varying degree's, high functioning piano tuners, professional tasters, marksmanship, perfumer's, etc. who have better sensory refinement than the average person.

The level at which a person has developed their visual spatial relationship response cues is going to be just as variable as it is with any other sensory utilization. The issues of seeing/perceiving visual cues related to spatial relationship are really no different than that of seeing gross vs. very small color variations. Some people have excellent color perception capability, while most people only have average (hence the reason for using calibrating tools) ability (hence, normal vs. enhanced/refined/etc.)

I don't think Philip was really talking about evolutionary and genetic adaptation as much as he was using those examples of utilization @ "use it or lose it" as it related to their current environment. Take a person from an urban setting where they have developed a robust desensitized/filtering to noise ... and they don't hear things quite the same way a naturalist does.

Live next to the EL and you hear things differently than a person who lives in a remote environment. Sit in an office 8 hours a day, and you'll likely have a different degree in your ability to see spatially from that of an iron worker who walks in death defying places all day. Switch jobs and (assuming survival) you see a gain/loss reversal in that ability. Extreme example for certain, but it does illustrate the adaptability and that "use it or lose it" does have a correlation environmental practical usage. Thus, the variability in individuals is inherent, even in "normal" individuals.



Apr 29, 2013 at 05:15 AM
jj birder
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p.2 #15 · Micro contrast ?


jj birder wrote:
And all three can fill pages and pages of obscure arguments in internet forums that rarely if ever get anywhere.


Are we there yet?



Apr 30, 2013 at 09:18 AM
philip_pj
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p.2 #16 · Micro contrast ?


Yes, Kent, and sorry if I am short with people, it was just speculation...I was thinking of guys like the MotoGP and F1 drivers, they have these wide eyes all the time. I read an article many years back on their vision, they subjected these US road racing champs to a battery of tests, they were all top category in all the tests, a self-selected group.

If you did not see this post here is one for you on Leica and Zeiss:

"We can define the quality of images over two dimensions, the spatial and tonal resolution. Leica is evidently the champion of the spatial resolution and the elimination of aberrations at all cost, with a very accurate definition and very crisp drawing that extends to the limit of the modern emulsion technology (or capture technology to include the sensors of digital cameras).

Zeiss favours a type of tonal resolution that brings rich colours and a smooth gradation over the whole image, not only *from corner to corner, but also into the image from foreground to background*.

Of course the differences are not a simple or clear-cut as described here. Spatial and tonal resolution are two sides of the same coin and can not be separated as two competing dimensions. If you have good spatial resolution, then tonal resolution is good too. But you can shift the balance and the relative weighting of the two. We are discussing lens lines that are quite capable of excellent imagery, but with a different design approach, that does become visible in practical photography." (Erwin Puts website, from The New Zeiss ZM Lenses, Part 3, September 4th 2005) - My asterisks.

So I do think it is a complex business, one that always turns up something, except for people who like to throw rocks, like mr birder here ;-) 'No' is the answer by the way. 'No' is always the answer, so you now have precognition on that question, lol.



Apr 30, 2013 at 11:11 AM
RustyBug
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p.2 #17 · Micro contrast ?


Philip,

+1 @ top athletes having excellent vision/spatial relationship abilities (vs the general populace).

Reminds me of baseball players talking about being able to "see the ball". Some struggle with how quickly they can see the ball once it comes out of the pitchers hand, others pick it up very quickly. The variance in visual acuity/perception @ spatial cues exists even among top athletes ... how much greater variance is there between they as a group and people who are not accustomed to watching things whiz by their head at 90mph.

Put a random group of people in the outfield to catch fly balls ... and you'll see again a wide range of how well people respond to spatial relationships. Not everyone has developed their vision to levels necessary to be a great hitter, outfielder, pilot or race car driver. That isn't to say they can't improve such with practice and training ... i.e. "use it or lose it" and the significant capabilities that exist within the realm of our brain/sense can be pretty astounding at times.

If you'd have told me that a person could have the ability to tactile detect a .001" vs. .002" variance, I'd have said you were full of it. Of course that was before I spent years routinely working with such tolerances. And to those who think a .001 variance isn't necessary, try doing an alignment to .0001 on a hard-cooupled motor/turbo-compressor. If you only aligned to .002, it would result in a very expensive failure.

While, it is impossible to predict how well a person can hone their individual capabilities by using them, it is reasonable to correlate that those (as a group) who use them in a more narrow capacity (i.e. less critical application) will not be as well honed as those who utilize them in extensively more challenging and critical applications.

The point here is that the range of variation in visual perceptiveness is pretty wide despite the concept that everyone would like to think they have really good vision ... till you step into the batter's box and get schooled to realize otherwise. Kinda like how everyone thinks they are good drivers based on their own self-perception.

Personally, my visual acuity has reduced somewhat over the years. I used to be able to see (with correction) to 20/10, yet now can only get to around 20/15. With normal being 20/20 I have always seen things that many others don't see (insert bad joke here ) or more accurately, before they do... until they perform closer inspection. I'm a pain to most optometrists because they think they're done when they dial me in to 20/20, but for me 20/20 is unacceptable.

As to the "3D-ishness" of a Zeiss, or the "clarity" of a Leica or the "colors" of a Rokkor ... there will always be individual variance in the level of discernment that exists among people. Some see it quite readily, others learn to see the diffs, while some never do and remain perpetual naysayers ... ardently claiming non-existence or myth. But if no differences exist, why would Leica/Zeiss put forth such an effort to produce as they do. That, and check the mfr on your optometrist equipment next time ... I doubt it'll say Canon or Nikon, but instead you may find it marked Leica.

Personally, I couldn't tell the difference between a lemon and a Leica when I first joined this board a few years back ... but that didn't mean the difference didn't exist, only that I couldn't discern it at that time. Lens design and the degree that it "matters" will always be debatable, largely predicated upon individual levels of discernment and needs of a given application.

Does one need a Zeiss or a Leica or a Rokkor to make a great photograph ... hardly. But for those who are discerning to the differences that inherent lens designs afford to the drawing styles produced by different lenses, it can make a difference to them. The degree of "well corrected" comes in to play for some as well. For others, not so much.

I find it folly for me to expect someone who uses a jackhammer all day to be able to tune a piano by ear at night ... until they truly desire to begin/resume refining their senses to that level of discernment, i.e. "use it or lose it". Imo, so it is with "3D-ishness" or "clarity" as well, some pick up on the subtle cues and differences an inherent lens design produces, others don't.



Edited on Apr 30, 2013 at 02:59 PM · View previous versions



Apr 30, 2013 at 01:38 PM
jj birder
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p.2 #18 · Micro contrast ?


Mr PJ. I'm a lover not a fighter and I never throw rocks in the vicinity of lenses. I could not predict that the speculation would be on brain science, physiology and genetics but when it appeared I had to laugh.

Thankfully we get back to photography due to your nice quote from Mr Puts. His points are similar to mine earlier (tendencies over absolutes; high quality lenses that make nicely rendered photos; all are worth using).

My point was and is that Zeiss (and Leica and others) makes nice lenses that OP can use and appreciate and see their qualities in pictures without worrying about the hot air.



Apr 30, 2013 at 01:53 PM
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