This is all very interesting, and Schneider and their customers will benefit from a reduction in variability lens to lens.
My question is whether or not the L-series lenses in time will exhibit the "Schneideritis" that was prevalent with so many of the Symmar-S lenses?
Well Neil
I guess you'll just have to buy a whole lot and wait for about 20 years then...
Seriously, it's a well documented issue to do with adhesives used by Schneider a long time ago. Schneider knows why it occurred. I have never seen an Apo Symmar with the condition and it has no effect on the optical charateristics of the lens. I hardly see why with new technology in adhesives and 20 years more manufacturing experience under the belt, the very latest lenses are going to suddenly develop "Schneideritis"... Too be honest element separation is a real optical roblem with lenses and I have not seen it on a modern Schneider, but have seen it on quite a few modern Rodenstocks... Now there's a problem to get your knickers in a knot about.
"With respect to these tests and Scott F's comment, I think we don't really need to test LF lenses probably any more than Chris and Kerry have. What those tests tell me is 1) top-the-line vintage glass can be as sharp as new glass; 2) there's more sample variation between the same lenses of recent manufacture than we'd like to see; and finally and maybe even most importantly, 3) a good example of an old lens may be as good or better as any particular new one WRT resolution."
I'm sorry, but chris and kerry's testing methods demonstrate that they've poured an enormous amount of time and energy into ... nothing. They simply don't understand optics beyond what was understood in the 1960s. Anyone flaunting resolution numbers as evidence of optical quality is just decades behind the current understanding of meaningful lens measurements. Their testing methods are essentially useless, as are their conclusions.
It is possible for vintage glass to be as sharp as modern glasss ... at a particular f stop, at a particular magnification, and on axis. maybe. But modern lenses are dramatically sharper overall, over a wider range of magnifications, and over a vastly wider angle of coverage. There are no two ways about it.
This doesn't mean that modern lenses are "better" ... if you prefer the subjective look of an old lens, then it's a better lens for you. But it's foolishness to think that that Schneider and Rodenstock and Nikon haven't figured out how to make sharper lenses over the last several decades.
We're clearly well into the era of diminishing returns. New lens generations seem to add less and less, and it's rarely an improvement in overall sharpness of the lens. It's qualities like the ones listed earlier ... sample-to-sample variation (one of the major improvements over vintage lenses), angle of coverage, sharpness at wide openings, and sometimes size and weight.
At any rate, anyone comparing lenses based on resolution really should do some research. You'll find that it's possible (common, actually) for a lower resolution lens to be sharper than a higher resolution lens. You might learn how to to read an MTF chart. And you'll see what spatial frequencies correspond to the ones your brain uses to perceive sharpness. Which is why a lens that produces high modulation (contrast) at 5-6 lp/mm (print resolution) but that has a low maximum resolution will appear much sharper than one that resolves many more lines per milimeter, but has lower modulation at 5-6 lp/mm. You'll figure out why those old resolution charts were used by the air force, and why they aren't of much use to anyone else.
On another note, Schneider actually tests all their lenses individually, by eye. They have highly trained guys who know how to interpret specialized test patterns that get projected through the lenses. They reaad them very fast, and for whatever reason are better at this than machines. This is the final quality control stage where the bad lenses get weeded out. I wouldn't be surprised if the other manufacturers did this too.
"I'm sorry, but chris and kerry's testing methods demonstrate that they've poured an enormous amount of time and energy into ... nothing. They simply don't understand optics beyond what was understood in the 1960s. Anyone flaunting resolution numbers as evidence of optical quality is just decades behind the current understanding of meaningful lens measurements. Their testing methods are essentially useless, as are their conclusions."
Well PaulR - they are subjective opinions backed by quite a bit of effort and research which they have been kind enough to share with the entire LF community - and while real genius like yourself may find this work completely useless, many haven't. Before berating their hugely generous effort and contribution, perhaps you could make a similar one? Or are your contributions restricted to cricital opinion?
I appreciate the generous spirit and the good faith of efforts like theirs, but at the same time I find it bizarre that they didn't do better research. The result is that they're providing extremely misleading information (worse in most cases than no information) to a whole lot of people. Granted, Chris and Kerry aren't prescribing dangerous drugs or leading people into cults, but they do seem to be providing information that more than a few people are basing big decisions on.
And I'm not touting myself as a genius, either. It doesn't take unusual gifts (I hope) to do some basic research on optics and human visual perception. An excellent book called Image Clarity came out fifteen years ago and was widely read by photographers and nerds alike. Since then there's been no end to the articles and research available on the web. It should take just a few mouse clicks to point you to well researched articles that demonstrated the uselessness of resolution numbers when evaluating lenses.
My contribution may well be limited to a critical opinion--but I'd be happier knowing it encouraged at least someone to examine other evidence before being misled by bad research, and spending a lot of hard-earned money on the wrong thing for the wrong reasons.
paul... would you mind sharing what's in your bag? you clearly have a different method of selecting lenses from the population-at-large, and as such i for one would be interested to hear which conclusions your approach led to.
---Scott
www.srosenberg.com
Paul,
While I undestand exactly what you are saying, and agree with a lot of it, you have jumped to some erroneous conclusions based and a whole string of false assumptions.
First, and foremost, whenever I discuss the results of the lens tests Chris and I conducted, I always start out by saying that people should not read too much into the results. I am always sure to point out that resolution is only one component of lens perfomance. Here's a quote from a post I made in the rec.photo.equipment.large-format newsgroup several years ago:
"For the lenses we tested, we measured resolution only. This is just one factor involved in the performance of a lens. It is the easiest to measure, and one that people seem to get excited about. But, contrast, resistance to flare, rendetion of out of focus areas, color rendition, coverage, etc. are also important (and not covered in our modest tests). "
I am also diligent in pointing out the flaws and limitations of our test methods. I encourage people NOT to take our results as gospel truth. As is evident from Schneider's claims, sample-to-sample variation is still an issue even in this modern day and age. Heck, even the focal length varies from sample to sample. It is not surprising that the performance would also vary by a small amount from the design target.
But modern lenses are dramatically sharper overall, over a wider range of magnifications, and over a vastly wider angle of coverage. There are no two ways about it.
Define "modern lens". Would a Super Angulon be considered a "modern lens"? Afterall, the f8 Super Angulon lens dates from 1954. Most large format lenses in current production were designed 20 - 30 years ago. The Fujinon C series dates from 1982. Most of the large format Nikkors date from the late 1970s. Even relativley new designs like the APO-Sironar-S and APO Grandagon are well over 10 years old. So, "modern" is a relative term. Some would say lenses that were designed with the aid of a computer would qualify as modern. That puts us back to the 1950s. Other would consider only multicoated lenses modern. That puts is back to the 1970s. And as I said even if you only consider current offerings, many date from the late 1970s or early 1980s.
They simply don't understand optics beyond what was understood in the 1960s.
Another false assumption.
Anyone flaunting resolution numbers as evidence of optical quality is just decades behind the current understanding of meaningful lens measurements.
No one is flaunting anything. The numbers are just that, numbers. We claim they are nothing more than what they are.
But it's foolishness to think that that Schneider and Rodenstock and Nikon haven't figured out how to make sharper lenses over the last several decades.
Another false assumption. Show me one quote where I've ever said anything to the contrary. In fact, if you will actually take the time to look through our results, you'll see that most of the really outstanding results (corner to corner) are for the most modern lenses. Occasionally an older lens will do well, usually in the center, but if you study the results you will see lenses like the 90mm Nikkor SW (a design that dates to the late 1970s, BTW), the 110mm Super Symmar XL, the 240mm Fujinon A, etc. tend to have the best overall test results. This is no coindidence. BTW, it's been two decades since Nikon has designed any new large format lenses. So, anything they've learned in the last 20 years is irrelevant to this discussion.
It's qualities like the ones listed earlier ... sample-to-sample variation (one of the major improvements over vintage lenses)
Bingo! This, in fact, was the genesis for our little lens testing chore. If you'd taken the time to do a little research, you'd know this all started as a search to find the "best" compact wide angle for backpacking with a 4x5. I started with five 90mm Angulons. As the tests results show, sample to sample variation was all over the map. It kind of grew from there. I have stated repeatedly that we were only really interested in the relative resolution of the specific lenses we tested. I have never encouraged anyone to accept our results as absolute or universal. In fact, quite the opposite.
You might learn how to to read an MTF chart.
Yet another false assumption. I am quite capable of reading an MTF chart - when I can get my hands on one. Problem is, I have NEVER seen a single MTF chart for ANY Nikkor or Fujinon large format lens. Nor can I locate one on any number of discontinued, pervious generation lenses. Sure, I'd love to have an MTF chart for every lens I own or am considering purchasing, but they simply aren't attainable for the majority of large format lenses other than current Schneider and Rodenstock models. And even then, they are based on calculated data, not measured performance of any particular lens. I have neither the time, equipment, nor money to do actual MTF measurements on my lenses. If you'd like to perform these measurements, I'd be happy to loan you every large format lenses I own for this purpose.
On another note, Schneider actually tests all their lenses individually, by eye. They have highly trained guys who know how to interpret specialized test patterns that get projected through the lenses. They reaad them very fast, and for whatever reason are better at this than machines. This is the final quality control stage where the bad lenses get weeded out. I wouldn't be surprised if the other manufacturers did this too.
Hardly a new method. This is exactly how Linhof tested their rebadged lenses going back to the 1950s (most recently using a Siemens Star tester). I have an old copy of Photo Techniques International from the early 1960s showing a Linhof employee performing these tests.
I appreciate the generous spirit and the good faith of efforts like theirs, but at the same time I find it bizarre that they didn't do better research.
Another false assumption.
An excellent book called Image Clarity came out fifteen years ago and was widely read by photographers and nerds alike.
I did read Image Clarity by John B. Williams back in 1998 - when Chris and I were performing our tests (I even mentioned it in a post in r.p.e.l-f I made at the time). A bit dry, but very informative.
It should take just a few mouse clicks to point you to well researched articles that demonstrated the uselessness of resolution numbers when evaluating lenses.
I would disagree that resolution numbers are useless. They are certainly not the only factor to consider, but I also don't think they should totally discounted.
The result is that they're providing extremely misleading information (worse in most cases than no information) to a whole lot of people. Granted, Chris and Kerry aren't prescribing dangerous drugs or leading people into cults, but they do seem to be providing information that more than a few people are basing big decisions on.
Don't you think you're being just a tad melodramatic here? Seriously, they are just numbers. We have never recommended anyone make any life altering decisions based on our results. I do not hesitate to recommend lenses I have found to be outstanding performers, but they are based on actual use, and not just test chart results. Please see the Future Classics section of my web site for several examples of lenses I recommend. If you disagree with any of these recommendations, or find them misleading in any way, please state your case, share your first hand opinions on the lens I discussed and offer alternative recommendations.
My contribution may well be limited to a critical opinion--but I'd be happier knowing it encouraged at least someone to examine other evidence before being misled by bad research, and spending a lot of hard-earned money on the wrong thing for the wrong reasons.
Could you please site one example where I've encouraged anyone to do otherwise. Seriously, you accuse me of bad research when you've obviously done very little yourself prior to attacking me here. Your conclusions about me and what I lenses I do and do not recommend are totally erroneous and based entirely on a series of false assumtions. I don't mind people disagreeing with me, in fact I encourage it. Dissenting opinions make for interesting debate. However, in the future please base your arguments on what I actually say, not on assumptions you choose to make. You have read far to much into our simple test results (exactly what you were cautioning others not to do). Again, they are just resolution numbers for a few lenses we happened to have access to. They are not a buyer's guide. They are not a guarantee that any lens you buy will be as good, better or worse than any other lens you may or may not buy. They are simply the resolution numbers, based on a very small sample size, within the limits of our test methdology, for a few lenses. They were never intended to be anything more. Ultimately, it is up to the individual to consider all available data (and opinions), and their own specific needs and budget, when buying any lens. To do otherwise is foolhardy and not recommended. Not now, not ever.
Kerry
i know i'm about to jump into a tank with much larger fish, put if i may interject.
Paul, i agree with you in that the tests Kerry and Chris performed should not be taken as absolutes. i know nothing of their testing procedures, but if they each made independent contributions to the table, then those tests should be taken separately. to further subdivide, only measurements made on the same day developed at the same time and analyzed by the same person under the same conditions can be taken as relative results. all others are useful only as an absolute metric for the specific lens returning the numbers and CAN NOT be taken as a relative metric to all other lenses tested. some of these sources of variation can be controlled with repeatability, but there was never any mention of the repeatability of the entire exercise, as such there is some bit of statistical uncertainty in what data is returned.
however, bear in mind that Kerry and Chris NEVER suggested that the results of a lens they physically tested, say a Fuji 240-A, had any implications to a Fuji 240-A they did not test. in fact, at the end of their table, they state as much...
"This is at best a relative (not absolute) comparison between these lenses. Kerry and I are simply looking for the Pick of the Litter."
they then go on to list many of the uncontrolled sources of variation, allowing the viewer to come to their own conclusions. i hardly think it's fair to blame Kerry or Chris if people misinterpret what they've put out there, particularly when they clearly list the limitations of their findings. they state very clearly that this entire study was so that Chris and Kerry could select the best of the lenses they had available to them. applying their findings to lenses they did not test is something they specifically cautioned against, but if people continue to do so, that certainly is not something you can fault Kerry and Chris for.
their measurements make for an interesting study, and i for one am certainly appreciative that they put them (and themselves, apparently) out there for public scrutiny. how others choose to use the data, especially after the authors cited the limitations or their findings, is out of their hands.
scott
---Scott
www.srosenberg.com
Boy did I open a can of worms. My apologies to Kerry; I know how long it takes to compile a carefully composed post this long.
But most people are still focusing on only one of several relevant lens issues (as Kerry and I have noted in other posts). For example, I know a published photographer who uses a Caltar II-E because it's flare resistant, and he chooses it over all others. How many of the lens cognoscenti would be caught dead with this "economy" lens on their Linhofs, Ebonys, and Arcas? I understand why he likes it if the reports are accurate; my 135mm Apo Sironar-S is bad about producing an iris ghost when pointed toward the light, and I have a multicoated Fuji 240-A that's ruined several pics with an out-of-frame sun. I'd gladly trade some resolution for high flare resistance.
We've also migrated to more saturated films and contrastier lenses to the point several people I know keep Astia and color neg film on hand because high sat films and lenses can't handle the tonal range of many scenes. I have noted that the vintage glass does render with less saturation, so maybe the contrast and saturation of modern lenses isn't as good a thing as some folks seem to believe (although controlling contrast and saturation by film choice is probably the better way).
Anyway, Kerry's and Chris' tests told me what I needed to know about resolution, and I also know that performance in the field under real conditions is probably more important, although no one ever seems to discuss it. Keep an open mind, question the "truths', and take more pictures!
Steve
Kerry,
I'm sorry for what must seem like a behind-the-back attack. Most of my points are directed toward anyone who is using resolution numbers to base comparisons on. Comments like 'doing some research might teach you to read an mtf chart' were not directed at you specifically, but at anyone who hasn't done research beyond looking at resolution tests.
I maintain a degree of perplexedness at why you would bother to do resolution tests (in the old fashioned mode of listing maximum resolution numbers). The problem with these tests in not that they're incomplete--you could argue that any objective test is incomplete in any number of ways. The problem is that they're completely misleading. In other words, there is essentially no correlation between masimum resolution numbers and subjective sharpness or clarity of a lens. In many cases there is actually an inverse relationship.
Here are some reasons:
While there is no real objective measure for resolution, it usually taken to mean the maximum frequency of line pairs (on a 100% contrast target) that can be discerned by eye. Different people have different thresholds for what they can see, but with one person doing all the tests there is at least a degree of consistency. That being said, what the tester is probably seeing at those high frequencies is faint renderings of the target lines, at perhaps 2% or 3% contrast.
Image detail rendered at sub-5% contrast at very high frequencies contributes nothing to a sense of sharpness or clarity. It in fact looks like haze in an actual photograph. Also consider that very little detail in real world subjects is differentiated by contrasts even approaching 100%. A tree branch against the sky might be 70% contrast; this you could expect to disappear completely if smallest enough to register at the highest tested resolution of a lens.
Our eyes establish sharpness using a number of cues, but by far the most important is the contrast (edge definition) of detail in the 5-6 lp/mm range (on a print). This sounds like low resoloution, but these details are actually quite fine.
Consider also that you cannot see detail finer than 11-12 lp/mm. Even with perfectly corrected vision, the rod and cone density of the human retina places a hard limit on this. This has been tested over and over again by different labs for different purposes*
This is why when you evaluate a lens using an mtf chart, you need to keep in mind what size enlargements you're most likely to make (not to mention other factors, like what magnifications, what f-stops, and what severity of camera movements--most mtf charts show these variables, at least somewhat).
A lens that produces excellent contrast in the 5-6lp/mm range (whatever that may translate to on the negative or chrome) will often do so at the expense of contrast at higher frequencies. Such a lens will test poorly in a maximum resolution test. Likewise, a lens that produces astonishing maximum resolution numbers will frequently produce lower contrast in the key 5-5 lp/mm frequencies. Prints won't look sharp. There will be tons of detail there that can mined from the depths with sharpening filters, but the overall look of the lens will be flat and dull. This is not actually a hypothetical situation; it's actually a standard compromise that lens designers make. They need to choose between a long, shallow sloping mtf curve (emphasizing high frequencies at low contrast--which would look good in resolution tests) or a flatter mtf curve with a sharper dropoff (emphasizing the frequencies that will make most prints look good, but that will typically score middling results on a resolution test).
This is why I think that for most purposes, resolution charts like the ones in question are actually useless. They're more than incomplete; they actually provide information that's going to be misleading to most people.
*It is true that you can see individual features that are smaller than, say 1/24 mm wide. With high enough contrast you can see much smaller features (you could probably see a 1 micron hole in black material with a bright enough light shining through it). But this isn't resolution. You are not "resolving" something that small. You are in fact seeing a blur of light that is much larger than the actual object. The test for resolution is how close things can be together before they blur into one.
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