Best to read the article, but here are snapshots of the charts.

I wondered the same thing. Maybe they consider, subjectively or not, things like build quality.

I am not defending their test but the full article does give a lot of test result detail.

The DxO methodology is not a secret - whether or not it's Six Sigma approved or not, I have no idea.

DxO use "Perceptual Megapixels" as their standard. To me it sounds like "we just made it up."
DxO Test Method

its all about real-world results, and my realworld perceptual megapixel's mama can beat yours up!!!!!!!!!!!!

Scores are for popularity contests, not for real world purchasing decisions. Nobody buys 'car of the year'.  They buy the car they want and just use 'car of the year, baby!' to brag about it to their peers if their chosen ride happened to win. all the weighting does is make a test subjective.  subjective? yes. because the weighting decision is itself subjective. "lets give resolution 23.67 points" why?  why not 23.68? maybe other things are more important to some people?
for the D800 just give us resolution and damn the torpedoes. if the resolving power of the lens is not up to the task of feeding the sensor we wanna know.  let us make our own decisions about all the other factors (edge, center, slightly-left-of center distortion, barrel rolls, whatever) dont tell us that resolution is worth so much and CA worth so much in the secret formula and pincushions worth so much and hide it in  a score. give us the results and let us score it ourselves.

DxOMark is a sham when their test results disagree with what you have decided ...

DxOMark is our savior whey they say what you want to hear!

Exactly.

Gregor, do you have any  links to learn more? Yes, I know google is my friend, but maybe you have a great link on this topic?

The idea is that if a lens is a certain resolution, then that is all the detail that it resolves.  Adding more megapixels beyond that point will result in no finer detail, since the camera is effectively making shit up.

The idea is fine.  The problem is in the implementation.  If you take their current favourite lens, the Sigma 35mm f/1.4, and put it on a D800, it yields ... I forget how much.  Something like 31 or 32 'perceived megapixels' at f/8.  Either way, not full resolution, but nearly.  Fine so far.

So theoretically, using that lens on a D700 should yield all 12 megapixels, since the lens outresolves the camera.  Using it on a D7000 should also yield all 16 megapixels, since the pixel density is the same as the 31 or 32 megapixels it is rated for on the D800.  If fact, using it on ANY Nikon body other than the crop-sensor 24MP bodies ought to yield full resolution.  But it doesn't work that way.  Why?  Who knows?  The way that the tests are written implies that they're testing the ability of the lens to fully resolve what the sensor sees, and yet other tests imply that this is not the case.

Scanner resolution works the same way.  Every scanner in the world (yes, even Imacons and drums) have the 'ability' to scan at a higher resolution than the lens can support.  Imacon even tells you that right in their software, by recommending a lower 'native' resolution.  Using a film with a larger grain structure ('bigger/fewer pixels') does not reduce native resolution - it just means that the scanner is sharper than the film stock.

So why then does changing pixel size make lenses less sharp, when they are claimed to be rated in a similar fashion?

Meh.  I agree with them sometimes, but I also agree with Ken Rockwell sometimes.  Write enough articles, and one of them is bound to be spot-on.  Monkeys typing Hamlet, and all.

My big gripe with them is that they claim to be doing scientific testing, and not 'artistic' testing.  Their fans regularly say that people just 'don't understand their methodology', and that we'd agree if he understood it.

But scientific testing isn't something that you make up from scratch.  There are tons of research labs with decades of experience in doing these exact same tests.  That DxO has chosen to abandon their methodologies and instead invent their own isn't very scientific at all.

But it makes for good writing.  I'll bet they make a killing on ad revenue.

DxO is to science what cable news is to political discourse.  Sure some real stuff sneaks in from time to time, but the whole process is dumbed down and buzzworded up to the extent that nobody is really learning anything useful anymore, as much as they're being pandered to.

Microcontrast is resolution.

one example from a different perspective....

http://www.luminous-landscape.com/tutor … rast.shtml

Nope. Microcontrast is the ability to distinguish between very fine tonal gradations.  Huge difference.

Never valued their analysis .. EVER.. Why?  Because they simply do not reflect the reality or user experience.  Period. No other reason.

I wouldn't be the first one to point this out... in fact, even among people who find value in DxO (for the reasons you hypothesized) many contend that their lens tests are pure garbage.  I agree... There are countless threads on this site and throughout the internet on how skewed and pointless DxOMark's "results" are. Should be no surprise to anyone who is familiar with their crappy techniques and findings.

Sites I value are Photozone, DPpreview, LensTip, SLRgear as well as other user forums and hands on experiences. DxO clearly caters to their sponsors (yes they are sponsored and paid for which is a whole other topic of discussion).

Well I'm using Roger Cicala's definition of microcontrast (http://www.lensrentals.com/blog/2009/06 … y-acutance). In digging around, it appears there may be diverging opinions on the exact definition of "microcontrast," but for our discussion nevermind. The thing you are talking about, let's call it "lens contrast," or "contrast" for short. I think everybody can agree on that.

That said, I'm still puzzled about some of your comments about lens contrast. Why do you think 85mm lenses have bad contrast? Here's an MTF chart of Nikon's 85/1.4G:



And here is the Nikon 85/1.8G:



Those charts are for the lens at wide open aperture--they look like they have good contrast to me. The red lines are for contrast (MTF at 10 lp/mm).

And secondly, it seems you are saying that it's a problem when lens reviews favor fast primes because of their good resolution. Why is that a problem? It seems that in 99 times out of 100, a modern lens with good resolution will also have good contrast. Are there any lenses you can point out where that is not the case?

Which is the same as optical resolution: the ability to resolve fine tonal transitions, usually measured in lines (or line pairs) per millimeter.

Creative Concept Studio wrote:
Best to read the article, but here are snapshots of the charts.

OK..I own a Nikon D800 and am VERY picky about image quality. The Nikon 50mm F/1.4 G they list as second best is the worst lens in my collection. The best they don't even list. The Nikon 16-35mm F/4 (Just a few L/m less res than the Nikon 14-24 but the lack of front filters made it a no go for me). Right behind that is the Nikon 85mm F/1.8 G. I HAD the F/1.4 version but it was soft till 4-5.6 so I returned it and got the F/1.8, the 50mil (Unfortunately) and credit toward the next sharpest lens in my kit, the Nikon 70-200 F/4 VR2. The F/2.8 version was about the same resolution with a bit better Bokeh but I have the 85mm G F/1.8 if I need that look. The 24-70 they love tested differently between 5 different copies I tried. Only one was as sharp as the rest of my lens. One was slightly lower and the others ranged from OK to soft.

Here is another companies tests http://www.lensrentals.com/blog/2012/03 … -selection

Nope

measuring microcontrast is done by shooting a target with a very subtly graded tone - it is entirely different than resolution

resolution is ability to render a spatial phenomenon

microcontrast is ability to render a tonal phenomenon

CP_ wrote:

Well I'm using Roger Cicala's definition of microcontrast (http://www.lensrentals.com/blog/2009/06 … y-acutance). In digging around, it appears there may be diverging opinions on the exact definition of "microcontrast," but for our discussion nevermind. The thing you are talking about, let's call it "lens contrast," or "contrast" for short. I think everybody can agree on that.

That said, I'm still puzzled about some of your comments about lens contrast. Why do you think 85mm lenses have bad contrast? Here's an MTF chart of Nikon's 85/1.4G:



And here is the Nikon 85/1.8G:



Those charts are for the lens at wide open aperture--they look like they have good contrast to me. The red lines are for contrast (MTF at 10 lp/mm).

And secondly, it seems you are saying that it's a problem when lens reviews favor fast primes because of their good resolution. Why is that a problem? It seems that in 99 times out of 100, a modern lens with good resolution will also have good contrast. Are there any lenses you can point out where that is not the case?

Resolution / Contrast are not the same thing as microcontrast -

Resolution / Contrast is about the ability of an optical system to differentiate spatial phenomenon -

any resolution beyond the Nyquist limit of the sensor creates more problems than it solves....

and the ultimate concern is not some techie concern with numbers but output -

Every professional quality grade lens from a major manufacturer since the 60s has been adequate for magazine sized output - even 40" gallery prints....

resolution we have long had in more than adequate abundance....  I have Nikon pre-AI lenses from the 60s that are way more than "sharp" enough for the D3x and D800..... 

NPS has a chart of lenses recommended for the D800 which includes many that "test" very poorly on some of these sites, for example, the 24-120f4N..... 

Microcontrast - as opposed to resolution -  is the ability to differentiate very small tonal phenomena  - it is not measured by shooting a target with tiny lines  (lines of resolution) but by shooting a target with a subtly graduated tonal range

There is in many cases an inverse relationship between resolution beyond the Artifact Free limit and microcontrast

I have never seen a rating site properly discuss microcontrast let alone "test" for it.

You're contradicting everything in the very same Luminous Landscape article you provided as support. You're not making very much sense. The article says "microcontrast" is another name for contrast which you can and do measure with a line pair chart at frequencies like 5 to 10 lp/mm. Maybe you can provide a different link that actually explains what you're saying, because that Luminous Landscape article does not help your case.

(And also I have no idea why you would say 85mm lenses somehow have lacking performance. That's a pretty bold statement that doesn't pass the sniff test. I'm not buying it--not without major evidence.)

don't forget the points awarded for
"we really need to do a long-term test to fully appreciate the technological advances in real-world shooting so we are glad that Canon/Nikon/Sony are loaning us one for a year with a drawerful of their best glass to really test the sensor at the limits"

separate tests for contrast. they dont use lines because its not about black vs white.  Its the "ability to take two small areas of slightly different luminance and distinguish the boundary of one from the other".

Long answer ahead...

Contrast as it applies to lenses is not simply the difference between the light and the dark of the entire picture. The difference between the light and the dark might be called "overall contrast" or "macro contrast."

From http://www.luminous-landscape.com/tutor … rast.shtml:

Many photographers and even some experienced and knowledgeable ones, seem permanently confused about contrast, especially when the word is used to describe lenses. In photography, like the word "speed" (which can refer to the maximum aperture of a lens, the size of the gap in a constant-rate shutter, or the sensitivity of an emulsion), the word "contrast" actually refers to several different things. "Contrast" in photo paper, for instance, or in a finished image, refers to overall (sometimes called "global") contrast, meaning how the materials distribute tonal gradation from black to white or lightest to darkest.

When we talk about lens contrast, we are not talking about that quality. What we're talking about is the ability of the lens to differentiate between smaller and smaller details of more and more nearly similar tonal value. This is also referred to as "microcontrast." The better contrast a lens has (and this has nothing to do with the light/­dark range or distribution of tones in the final print or slide) means its ability to take two small areas of slightly different luminance and distinguish the boundary of one from the other.

You can have a lens of very low contrast that can be made to transmit the same overall range of light to dark or white to black as one with high contrast. It will just show much less micro detail in the scene, and look relatively muddy and lifeless. Some pictorialist-era pictures actually have a full range of tones from white to black but show (by design) exceptionally low degrees of what we would call lens contrast. Low lens contrast is also created when you put a "softening" filter on a lens you can still print the picture with an overall contrast from pure white to maximum black, but the microcontrast will be severely curtailed.

...Lens contrast refers to the lens's ability to discriminate tonally between small adjacent areas in the print, lending a sense of texture and surface.

...Technically speaking, MTF measures both contrast and resolution more or less simultaneously. In a photographer's reading of an MTF chart, however, generally the position of the topmost lines (typically 10 lp/mm, sometimes 5) will have the highest correlation to visible lens contrast. The lowest set of lines (30 or 40 lp/mm) will correspond best to actual resolving power.

For something even more in-depth, you can read this: http://www.zeiss.com/C12567A8003B8B6F/E … ven_EN.pdf

A more digestible read is this: http://www.lensrentals.com/blog/2009/06 … y-acutance. And while the ideas in it are the same, the vocabulary is a little different (this one uses a more narrow application of the word microcontrast).

Now, what I am on board with what Fotografica Gregor is saying is that resolution-biased reviews can overlook certain lenses that don't actually have tons of resolution, but still look sharp and take great pictures in most situations. I'm on board with that. But the other stuff needs clarification.

Gregor, many thanks for the excellent links to references that you post.  Thank you for sharing. 

This article, among other things, re-directed my attention to the importance of lens coatings.  I would have to question if small manufacturers like Sigma and Tamron have the ability to do state of the art coatings -unless, of course, they are able to farm this step out to bigger companies that are capable of nano-coating glass.