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Messages - jrista

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1486
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 10:12:54 PM »
When you get into what diffraction actually is, you learn that it is not actually "caused" by anything. Diffraction is an intrinsic trait of light that exists within the wavefront. It is often described as the "bending" of light caused by it's encounter with an obstruction or an opening. That's a useful description to describe the effect of what is happening, however sadly it is not actually an accurate description of what is actually causing the effect.

Diffraction happens with waves and one method that we use to model light's behaviour is to say that in some circumstances it behaves like a wave. Diffraction is not an intrinsic property of light at all, it is a trait of waves and how waves behave.

Please stop spreading bad science.

I'm sorry, but I beg to differ. Here is an article that details the actual science of what a diffracted wavefront is, how diffraction in a wavefront presents and behaves, :

http://www.telescope-optics.net/wave.htm
...

You don't know what you don't know and you're just using a random web article that happens to provide a theory that makes sense to you.

Answering your questions is beyond my ability, schooling or training.

Go find a course on physics that teaches about light and learn about it the way professionals do. An astronomer does not learn about physics from the web. Articles on the web greatly simplify things.

LOL  :o  ???

That isn't a random web site. I found that site years ago (probably before I ever even started posting on these forums) while researching optics for photography (I think that would make it even my pre-DSLR days, as I like to research concepts, theory, equipment, brands, etc. before I buy anything.) I pulled that site out of my bookmarks, bookmarks that I've been stringing along from Opera version to Opera version for years.

It's one of the best web sites on the net that covers this stuff in as detailed, specific, mathematic, and scientific a manner as you can find, too! I seriously challenge you to find a better resource than that that explains the concepts better, or more correctly. And it is FAR from "simplified". Did you even check it out, did you actually look through the site at all? Do you know how much science and mathematics is used in that site to explain the concepts of optics, refraction, reflection, diffraction, and every other aspect of telescopes? It's riddled with math and complex theories, the same exact theories I LEARNED IN MY PHYSICS CLASSES IN COLLEGE.

My knowledge doesn't come only from the web...the web is simply an easy source for reference when one is trying to back up their arguments with hard facts (something I have done plenty...I still don't see any references from you to back up anything your saying.) I've got my old college physics books on my bookshelf here, right alongside, um, oh yeah, Feynman's QED (fantastic book, that.) I also have Newton's "Optiks" on the same shelf, as a nostalgic historical reference and read.

I guess I should have expected you to try and refute hard science. I do challenge you to actually read the site, instead of simply assuming it is unscientific or otherwise flawed simply because I'm the one who posted the link. You might actually learn something, find it edifying.

1487
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 08:42:58 PM »
To refer to the second paragraph- in short, light has been theorized both as a waveform and as a particle- not because one leads to the other, rather because it has characteristics of both (including diffraction). It is not purely a wave. So yes, diffraction is a property of light, which likens it to a wave.
Is there a difference in magnetic and electromagnetic waves? Yes, the former cannot proceed through vacuum.

Just to touch on a point. A magnetic wave is an electromagnetic wave. There is no electronic or electrostaic wave, nor is there a magnetic wave. There are electromagnetic waves. Magnetic fields do indeed exist in space, which is a vacuum. NASA's space probes have been equipped with both a plethora of electromagnetic sensors as well as plasma wave sensors ever since the first ones were sent into space. We've measured the effects of electromagnetic fields in space, which includes the measurements of electric fields, magnetic fields, and plasma waves (electromagnetic effects propagating within free electrons and positively charged ions...plasmas...within interplanetary and interstellar space.)

Now, if you are referring to the propagation of a wave through magnetized mediums (say the waveform that forms in iron particles that conform to the electromagnetic field around a magnet), then that is a bit different. I guess that could be called a "magnetic wave."

Oops, typo. I meant MECHANICAL waves. Mechanical waves cannot proceed through vacuum.
See, my typing sucks!

Ah! That makes a lot more sense.

1488
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 08:42:10 PM »

I'd also say that light isn't simply modeled after waveforms. Light IS waves. It's waves in full three dimensional space, which is also why they can behave as particles...a purterbation in an electromagnetic field, focused finely enough, would behave as a particle...a packet of energy that has a quantity, vector and magnitude. One could consider every point of a wavefront as a finely focused "photon". Wave-particle duality simply describes the nature of matter in general...that they are divisible (and quantizable) quantities of mass (particle), and that matter has the capability of transferring energy (wave). Light is not the only thing that, theoretically, exhibits wave-particle duality. All quantum particles do. Which means that all quantum particles are also waves.

What exactly do you mean by "is"?
If you mean "is equal to" than you are basically saying that all quantum particles are light (which is untrue)

Diffraction isn’t inherent to waves because light is a wave, it’s inherent to waves period.

You misunderstood. Light is waves. It isn't "a wave", as that would imply a singular wave. The energy field that represents light propagates through space as waves.

Other quantum particles are also waves. They propagate energy as waves, yet also have mass, therefor they ALSO have wave-particle duality.

I entirely agree that diffraction is inherent to waves, period. That's what I was saying. ;P

1489
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 05:50:51 PM »
In any case, I think the reason for the onion rings in this case is the aspherical elements rather than diffraction.

If the onion rings were present in every photo of every light source, and if every OOF blur circle produced identical onion ring patterns, I would agree. However the candle lights produce no onion ringing at all, and the various electric lights produce differing onion ring patterns. Given that, it seems more logical to me that the source of the diffraction is external to the lens and camera. In other words, it's caused by the light sources themselves...say the glass or plastic bulbs surrounding whatever is actually emitting the light.

My knowledge of bokeh structure is far inferior to my knowledge of optics. However, the link you posted itself suggests that the onion ring is due to aspherical elements in the lens rather than diffraction.

http://toothwalker.org/optics/bokeh.html

One general note: diffraction is not caused by the light source. It is caused by objects in the path of light. You are suggesting it is happening at the level of the impurities in the light bulb, I am suggesting it is at the level of the lens elements. Also, even the candle light is not a pure light source. The yellow part is actually incandescent carbon particles that don't burn fully. Lens elements behave differently with different sources of light (in other words, diffraction characteristics will vary according to the nature of light emitted), so while it may not diffract candle light, it might diffract electric light. I don't have the Physics knowhow to predict the exact mechanism.

I do agree, that the aspheric element can cause the onion ringing effect. However, and I am honestly trying to think logically here, would that not effectively REQUIRE that every light source exhibit the effect, and that every boke blur circle exhibit it in the same way? If the onion ringing, specifically in the case of Eldar's photos, was a consequence of the aspheric element, I truly do believe that the candles would have exhibited the effect as well. They would have to, since the effect is caused by the lens, and not a bulb or something else in proximity to (around or between) the light source itself.

Additionally, if you blow Eldar's sample images up, most of the effects on the blur circles themselves are inconsistent from circle to circle. If they were consistent, I would agree with you 100%, however they are not consistent. The lack of onion ringing in the candles and the inconcistencies with which each blur circle exhibits lead me to believe the problem is external to the lens.

That is not to say lenses cannot cause effects like this...they can. However I also believe that a $4000 lens would NOT be exhibiting onion ringing. It's a very noticable and ugly effect, very ugly effect, that I would not be spending $4000 on a lens that had that problem. I am a big fan of Canon glass, however I have great respect for Zeiss, and I cannot imagine them creating a lens like the Otus with such a nasty flaw.

To refer to the second paragraph- in short, light has been theorized both as a waveform and as a particle- not because one leads to the other, rather because it has characteristics of both (including diffraction). It is not purely a wave. So yes, diffraction is a property of light, which likens it to a wave.
Is there a difference in magnetic and electromagnetic waves? Yes, the former cannot proceed through vacuum.

Just to touch on a point. A magnetic wave is an electromagnetic wave. There is no electronic or electrostaic wave, nor is there a magnetic wave. There are electromagnetic waves. Magnetic fields do indeed exist in space, which is a vacuum. NASA's space probes have been equipped with both a plethora of electromagnetic sensors as well as plasma wave sensors ever since the first ones were sent into space. We've measured the effects of electromagnetic fields in space, which includes the measurements of electric fields, magnetic fields, and plasma waves (electromagnetic effects propagating within free electrons and positively charged ions...plasmas...within interplanetary and interstellar space.)

Now, if you are referring to the propagation of a wave through magnetized mediums (say the waveform that forms in iron particles that conform to the electromagnetic field around a magnet), then that is a bit different. I guess that could be called a "magnetic wave."

But that is not relevant here. Light has characteristics of an electromagnetic wave.
I didn't say diffraction is limited to light waves. Light exhibits diffraction. Waves exhibit diffraction (quite independently). Hence light = waves. Is it that simple? No, because light has particulate properties, too.
You are right, light is not modeled after waves. Light is a wave. But then, it is also a particle. One doesn't imply the other, but they are clearly not mutually exclusive.

In any case I am not an expert in Physics, my field is Biology. My knowledge in Physics is quite limited, and I type rather slowly, so I shall stop here. But the information above is quite accurate as you can check out.

I think we pretty much agree on everything else.

1490
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 20, 2014, 05:14:50 PM »
Why on God's green Earth would I compare RAW files with no NR when I never work that way and neither does anyone else?
The 70D is measurably and visibly noisier than the 1D IV. The data backs that conclusion.

Now don't start going Risedal on us, Jon.   ;D

To paraphrase Bailey Quarters, you're both right: the numbers don't lie AND the numbers don't always matter in the final product.  Now, make nice and go back to talking about 7D2's and unicorns.   :P

Hey, hey now. I resent the Risedal comment. :P I've never been an ragingly oblivious incorrect buffoon. I'm just a plain old standard buffoon.  ;D

1491
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 04:28:50 PM »
I am not spreading bad science. I'm explaining the ACTUAL nature of light. Light propagates as a diffracted wavefront, wherein each and every point along that wavefront results in secondary wavelets that constructively interfere to maintain the wavefront, except when it encounters an obstacle, in which case the interference is both constructive and destructive, thereby producing the familiar wave patterns, like an Airy Disc.

Jon, with due respect Dilbert is raising a point about diffraction not being inherent to light, but secondarily attributable to light based on the waveform model (he is wrong, of course).
Your post above and the quoted sections describes how diffraction is a property of light waves, but that would be applicable even if diffraction was attributed secondarily to light AFTER modeling it after waveforms IMO.

To find that answer, I recommend "Principles of optics: electromagnetic theory of propagation, interference and diffraction of light" by Born and Wolf.

So, regarding all of this. Are you saying there is a difference between mechanical waves and electromagnetic waves? To me, waves are waves. As much as I said that diffraction is inherent to light, light is a wave. Diffraction is inherent to waves. I mean, that's what the Huygen's Principal is. It isn't limited to light waves.

I'd also say that light isn't simply modeled after waveforms. Light IS waves. It's waves in full three dimensional space, which is also why they can behave as particles...a purterbation in an electromagnetic field, focused finely enough, would behave as a particle...a packet of energy that has a quantity, vector and magnitude. One could consider every point of a wavefront as a finely focused "photon". Wave-particle duality simply describes the nature of matter in general...that they are divisible (and quantizable) quantities of mass (particle), and that matter has the capability of transferring energy (wave). Light is not the only thing that, theoretically, exhibits wave-particle duality. All quantum particles do. Which means that all quantum particles are also waves.

Even though waves can move through materials, such as water and air, waves are simply the propagation of energy. I would argue, with Huygen's Principal backing me up, that the description of diffraction in an electromagnetic wavefront is also the description of diffraction in any wavefront. It's all the same thing..waves are waves. So it really wouldn't matter if we were talking about a "mechanical" wave propagating through water that passes through a slit, or sound, or light. The actual fundamental reason diffraction exists and exhibits the properties it does is because it is an intrinsic trait of the energy propagating via the wave, not the material the wave is propagating through.

1492
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 04:14:22 PM »
In any case, I think the reason for the onion rings in this case is the aspherical elements rather than diffraction.

If the onion rings were present in every photo of every light source, and if every OOF blur circle produced identical onion ring patterns, I would agree. However the candle lights produce no onion ringing at all, and the various electric lights produce differing onion ring patterns. Given that, it seems more logical to me that the source of the diffraction is external to the lens and camera. In other words, it's caused by the light sources themselves...say the glass or plastic bulbs surrounding whatever is actually emitting the light.

1493
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 03:19:51 PM »
When you get into what diffraction actually is, you learn that it is not actually "caused" by anything. Diffraction is an intrinsic trait of light that exists within the wavefront. It is often described as the "bending" of light caused by it's encounter with an obstruction or an opening. That's a useful description to describe the effect of what is happening, however sadly it is not actually an accurate description of what is actually causing the effect.

Diffraction happens with waves and one method that we use to model light's behaviour is to say that in some circumstances it behaves like a wave. Diffraction is not an intrinsic property of light at all, it is a trait of waves and how waves behave.

Please stop spreading bad science.

I'm sorry, but I beg to differ. Here is an article that details the actual science of what a diffracted wavefront is, how diffraction in a wavefront presents and behaves, :

http://www.telescope-optics.net/wave.htm

And I quote:

Quote
An imaginary surface connecting wave points of identical oscillatory motion, or phase, is called phasefront. Geometrical approximation of the phasefront, based on the identical ray optical path length (OPL) from the source is called optical wavefront, or simply wavefront. For optical telescopes, phasefront and wavefront are, for all practical purposes, identical as long as the wavefront error remains relatively small. The difference between the two comes from the latter increasing directly with the nominal wavefront deviation, while the former follows the increase nominally, but effectively it oscillates from the maximum constructive interference for wavefront points deviating any whole number of waves - including, of course, zero deviation - decreasing to zero constructive interference from any wavefront point deviating by a whole number of half-wave deviations.

Ray, on the other hand, is simply a straight line with the origin at the point-source, that remains perpendicular to the wavefront. While rays are useful in presenting geometrical aspects of optical phenomena, they represent only a tiny fraction of the total energy propagating through the energy field. Furthermore, it is only their geometric properties that are being considered. Therefore, ray (or geometric) optics has no direct relation with the physical properties of the energy field.

The geometric tools we use to describe light, such as rays, are simply that...tools used to describe light. They do not, however, actually have anything to do with what light actually is or how it actually behaves.

And I quote further:

Quote
Diffraction

According to Huygens' principle, every wavefront point is a source of secondary wavelets, through which spreads in the direction of propagation. This constitutes a micro-structure of energy field propagation, with the energy advancing in the direction of the wavefront, but also spreading out in other directions. Principal waves, or wavefronts, form in the direction determined by extending straight lines from the point source. Waves moving in other directions generate phase difference, preventing them from forming another effective wavefront (FIG. 1, top right). However, these diffracted waves do interfere with both, principal waves and among themselves.

As a consequence of the existence of diffracted wave energy, placing obstruction of some form in the light path will result in the "emergence" of this energy in the space behind obstruction. But the obstruction did not change anything in the way the light propagates - it merely took out energy of the blocked out principal waves, with the remaining diffracted field creating some form of intensity distribution in the space behind obstruction - the diffraction pattern.

Similarly, by limiting energy field to an aperture, the portion passing through it is separated from the rest of the field, and its energy - this time consisting from both, aperture-shaped principal waves and diffracted waves within - will create a pattern of energy distribution behind the aperture. Again, there is no actual change in propagation for the light passing the aperture, including those close to the edge of obstruction (light does not "bend around the edge"); whatever the form of energy distribution behind the aperture, it is caused by the interference of primary and diffracted waves inherent to the energy field (FIG. 1, middle and bottom).

Diffraction is interference. If you study the nature of light and waves enough, you'll find many a renown scientist making that claim, that diffraction and interference are essentially the same thing. Diffraction is an intrinsic property of propagating light waves. When an obstruction blocks light or an opening passes light, the void left behind by the light that was blocked is filled with the diffracting light (the natural effect of each and every point along a wavefront sending out secondary wavelets.) The appearance of a diffracted wavefront is due to the interference those wavelets cause with each other. In case you don't actually read the entirety of the quoted text, let me point out the most important part, again:

Quote
Again, there is no actual change in propagation for the light passing the aperture, including those close to the edge of obstruction (light does not "bend around the edge"); whatever the form of energy distribution behind the aperture, it is caused by the interference of primary and diffracted waves inherent to the energy field (FIG. 1, middle and bottom).

I've emphasized the key points.

I am not spreading bad science. I'm explaining the ACTUAL nature of light. Light propagates as a diffracted wavefront, wherein each and every point along that wavefront results in secondary wavelets that constructively interfere to maintain the wavefront, except when it encounters an obstacle, in which case the interference is both constructive and destructive, thereby producing the familiar wave patterns, like an Airy Disc.

1494
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 20, 2014, 12:55:20 PM »
I wouldn't call the difference in noise between the 1D IV and 70D a "wash". Compare the noise test results from DPR:

Why on God's green Earth would I compare RAW files with no NR when I never work that way and neither does anyone else?

If your photography consists of staring at zero NR, ISO 3200 black and gray patches at 100% until your eyes cross, buy a Nikon or a Sony. Then you can boost those RAW files +5 stops and really have some fun staring at patches.

Well, because the way YOU do things doesn't really matter for everyone else. :P However, for the sake of discussion, I most frequently do not apply NR to my images. I do everything in my power to maximize my signal strength up front, so that noise is minimal. I also usually publish most of my work with fairly considerable downsampling (my 5184px images are usually uploaded at 1140px on my blog), and the downsampling does enough basic averaging to reduce noise to an acceptable level in a standardized way (so if I downsampled and compared a 1D IV image with a 70D image after downsampling, the results would be the same.)

Noise reduction, in the case of RAW images, is not a feature of the camera. It is a feature of post-processing software. If we are to have an objective discussion about CAMERAS and their SENSORS, the ONLY way to compare the noise levels of two cameras is directly, with a RAW image. If you apply noise reduction, then export as a JPEG...well, we are no longer comparing RAW now are we? Were comparing denoised jpegs (and the algorithms that perform noise reduction.

Additionally, NR is a subjective process, and how well it works is affected by a number of factors. The noisier 70D images will require more noise reduction. The farther you push an NR routine, the more blurring it will introduce. The more blurring introduced, the lower the resolution of the 70D images, which puts it at a further disadvantage to the 1D IV. Comparing swatches that have been run through a noise reduction process means your no longer comparing the most objective data.

Sorry to burst your bubble here D by disproving your theory that the 70D has the same low noise as the 1D IV, but there it is in gray, black, and blue. I'm sorry that I have to share this kind of information, but to be frank, I honestly do not believe it is fair to anyone else to simply let anecdotal claims that have no basis in fact stand without providing as much objective and honest data as I can so everyone can see for themselves and make their own determinations.

The 70D is measurably and visibly noisier than the 1D IV. The data backs that conclusion.

1495
Third Party Manufacturers / Re: Zeiss Otus Initial Impressions
« on: April 20, 2014, 12:45:19 PM »
Not to re-open a closed case, but here's another thought - what happens if you throw a polarizer on the lens?  In theory it should "straighten" the beams of light and eliminate the effects of diffraction, right?

When you get into what diffraction actually is, you learn that it is not actually "caused" by anything. Diffraction is an intrinsic trait of light that exists within the wavefront. It is often described as the "bending" of light caused by it's encounter with an obstruction or an opening. That's a useful description to describe the effect of what is happening, however sadly it is not actually an accurate description of what is actually causing the effect.

Light from a point light source is emitted in a spherical wavefront. That wavefront, in an ideal vacuum, will emanate progressively outwards, in perpetuity, without changing. The entire time the wavefront is propagating, it is also diffracting. Even though there is nothing to diffract from...the diffraction is intrinsic. At every point along the wavefront, at every moment, light diffracts...separates and spreads...in a predictable fashion and in such a manner as to reinforce the basic nature of light...inverse squared falloff. (If you think about it for a bit, for inverse square falloff to actually work, even in an ideal vacuum SOMETHING would have to be happening to the light in the wavefront to make it disperse...in the absence of everything else, the dispersion would have to be intrinsic...diffraction.)

If you throw up an obstruction in the path of that light, the obstruction DOES block the light behind it. Any light not blocked by it continues on, however now there is a void in the wavefront. Without that void, the parts of the wavefront that make it around the obstruction don't actually "bend" to create the ring-light halos around the obstruction. They are diffracting, which is causing the light to spread out in a certain way. Same deal with an opening, only in this case all light except what passes through the opening is blocked, and the light that passed through it is still diffracting, still causing it to spread out.

So, since diffraction is an intrinsic property of light, will the use of a polarizer "straiten" light out? A polarizer is a filter that is designed to allow light with a certain radial orientation through. The filter could be thought of as basically a series of extremely thin, tall slits. The light with the same orientation as the slits will get through, all other light will be blocked. Each slit could be thought of as an aperture. Since diffraction is intrinsic...all the light that passes through the polarizing filter will still be diffracting. Even if your using a circular polarizer, the light that exits the quarter wave plate is also still diffracting. Diffraction cannot be stopped, because it is a fundamental trait of the behavior of light in a wavefront.

1496
Canon EF Prime Lenses / Re: Canon EF 600mm f/4L IS II USM
« on: April 19, 2014, 08:05:20 PM »
Took some images of the eclipse we had a few days ago with my 600. They turned out pretty great, if I may say so myself. ;)

Orion Atlas GEM
Canon EOS 7D
Canon EF 600mm f/4 L II
BackyardEOS (For image sequence acquisition)

ISO 100 @ f/8, shutter speeds from 1/250th to 15s.
Amazing photos. Congratulations!
And a little cheating I might say. The Atlas GEM helped in low shutter speeds - this is not the cheating I am talking about  :) -  and the eclipse was visible from US - this is the cheating I was talking about  ;D ;D ;D.
(Many  :( :(  or even  >:( >:( for me!)

:P

There are three more total eclipses coming. This was the first of the current tetrad, so there is one in October, and another in spring and late fall next year. The latter two are supposed to be more visible from other parts of the globe. I'll only get to see them at sunrise or sunset (which might in and of itself make for an interesting wide angle progression.)

1497
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 19, 2014, 12:54:16 PM »
I wouldn't call the difference in noise between the 1D IV and 70D a "wash". Compare the noise test results from DPR:



That's a very noticeable difference. There isn't enough of a difference in image size to completely normalize the results with downsampling (remember, it isn't simply the image dimensions you have to factor in, it is also the difference in sensor area. So simply downsampling the 70D image to 1D IV image dimensions is insufficient to reduce noise to the same levels.)

Personally, based on the gray and black swatches, the 1D IV seems to have quite a bit less noise at ISO 3200 than the 70D. Unless the 7D II hits the streets with a massive improvement in Q.E., I wouldn't expect there to be much of a difference. If Canon really manages to improve their Q.E. to modern standard (i.e. 55-60%), there could be a slight improvement, one that is recognizable over the 70D, but still insufficient to overcome the greater total area benefit of the 1D IV.

1498
Canon EF Prime Lenses / Re: Canon EF 600mm f/4L IS II USM
« on: April 19, 2014, 04:19:58 AM »
Took some images of the eclipse we had a few days ago with my 600. They turned out pretty great, if I may say so myself. ;)

Orion Atlas GEM
Canon EOS 7D
Canon EF 600mm f/4 L II
BackyardEOS (For image sequence acquisition)

ISO 100 @ f/8, shutter speeds from 1/250th to 15s.

1499
EOS Bodies / Re: 1d IV vs. 7D II
« on: April 18, 2014, 10:04:43 PM »
@Don: It looks like those are the paper release dates. The 1D X was announced in 2011, but it didn't actually hit the shelves until early summer 2012 (and maybe even later than that, as a lot of the early models used in the Olympics were ultimately replaced). The 1D X has a technical market life that is even shorter than the 5D III, which means the 7D is that much older than the next oldest Canon camera model.

Either it is REALLY going to be something utterly incredible...or Canon is killing off the 7D line. At this point, I'm beginning to wonder if Canon can really achieve the level of "incredible" the 7D would really need to be to fill the shoes everyone expects it to...

1500
To clarify, "Best at FL+aperture" refers to the Lens Score, which is based primarily on 'performance in 150 lux illumination' (like a dimly lit warehouse).  The Lens Score is only secondarily influenced by the optical metrics (sharpness, CA, etc.), despite those metrics being listed under the Score. That's why almost all lenses are 'best' wide open, even though the optical metrics are rarely highest at max aperture.

Consider that the Sigma 50/1.4 A is not 'best at 50mm f/1.4', but at f/2.  Since giving up a full stop of light is obviously not better for 'performance in 150 lux' that suggests that one or more of the secondary factors measured for the Sigma 50/1.4 A at f/1.4 were sufficiently bad to counteract the loss of a stop of light.  Or it could be that DxO just screwed up their testing, it certainly wouldn't be the first time.

LOL, no, not the first time.

I'm curious why the Sigma 50 A would bet the "best at f/2" treatment...but not the Canon 50L. It's quite clear that the 50L does not perform ideally (at least according to DXO's metrics) at f/1.2...and yet you can't even select f/1.4, f/1.8, or f/2 when comparing apertures with other lenses.

It's little things like that that always make me wonder if DXO really does have a bias against Canon. It seems they very often put Canon equipment in the worst possible light, and take special care to put other brand's products in the best possible light (such as the Sugma 50/1.4 A being best at f/2.)

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