Messages

1156

EOS Bodies / Re: Anti-aliasing filter in 1DX

« on: April 04, 2012, 01:17:31 PM »

I had thought that Canon had put on a thinner, not thicker, AA (low-pass) filter in the 5D III. I remember it being explicitly called out in this blog:

http://blog.jeffascough.com/photographers/2012/03/canon-eos-5d-mark-iii-review.html

As I understand it, Jeff Ascough is pretty tight with Canon, and would likely have fairly in-depth knowledge about the 5D III, so I'm not sure his claim about a thinner AA filter can simply be written off as hearsay or some such.

1157

EOS Bodies / Re: Quality differences on APS-C cameras?

« on: April 03, 2012, 06:22:17 PM »

I have just gotten my 2x III extender and wanted to test out focal lenght. I shot the first four with my 5D II, and then I wanted to see how the 640 effective focal length would be, and I shot the last with my wife's 600D. I notice some color differences. I have been thinking about getting a 7D as a secon camera, but my question is: Is the quality of the 7D versus the 600D large?

In terms of IQ, you shouldn't see any difference at all, as both cameras use the same sensor. The benefits of the 7D are largely in terms of performance...AF performance, frame rate and continuous shooting, weather sealing, etc. If you don't need better AF, high speed continuous shooting, or weather sealing, I would stick with your 600D.

1158

EOS Bodies / Art Morris in love with 5D III!

« on: April 03, 2012, 11:37:43 AM »

Art Morris, a world-renown bird photographer who is well-known for his use of f/8 AF, recently posted an article proclaiming his praise for the 5D Mark III and its AF (despite the lack of f/8 AF.) He indicates that the AF performance of the 5D III in the hands of a skilled Canon photographer is nothing less than stellar, producing an extremely high rate of keepers. Perhaps this will answer some of the questions about the capabilities of 5D III AF, IQ, etc. and whether it really is up to snuff or not:

http://www.birdsasart-blog.com/2012/03/28/the-canon-eos-5d-mark-iii-im-in-love/

When I got home and viewed the series of flight images I realized that my 5D III AF predictions were true. Every image was sharp. Even when the bird flew behind a wire or the telephone pole. The files are luscious, incredibly detailed and sharp with natural color.

...

I must tell you, I have never been so excited about a new camera before.

I had headed out even without taking a look at the camera body manual. I had gone through all the Menus and I must say I was mega-confused…. As you can see that did not hurt my images though. As it turns out I was in Central Sensor Expand AF area. I plan on experimenting with all of the AF area selection modes. And I will of course be working hard on the BAA 5D Mark III User’s Guide. I have even figured out how to toggle between the various AF area selection modes. I could not do that this morning  . And it took me quite a while to figure out how to set up rear focus….

1159

EOS Bodies / Re: My first real shoot with the 5DIII

« on: April 03, 2012, 11:02:23 AM »

If you count dynamic range being from the darkest pixel to the brightest, there is a LOT of dynamic range in those photos. There are some very bright highlights, particularly off the chrome. I am not surprised that you couldn't capture it all in a single shot without pushing down the shadows. If I had to guess, I'd say...counting the very bright highlights...that there was more than 14 stops of DR in those shots.

You don't say. How can a $hitty Canon sensor manage that kind of DR ? I know preliminary reports show that the DR of the 5DII and III are similar, but the MKIII is a nice step up from the 5DC. The first shot was captured in a single exposure, while I usually need to merge at least two exposures together in similar shots with the 5DC. I actually had couple of separate exposures in which I hit the dark side of the car with flash, and planned on layering it in, but I was able to pull out enough shadow detail to eliminate the need to do so. 5DIII = less post processing for me, so I can't complain

Well, keep in mind, the shots themselves have some blocked shadows and some small areas of blown highlights. I don't think you captured the full dynamic range of the scene in those shots, which is why I think you might have had some issues metering and needed some extra light. (Note: The highlights themselves, although mostly very tiny and point-like, could very well represent one to two stops of additional DR that you are not able to capture.)

Second, the iFCL meter DOES take into account focus, and it will attempt to weight metering around AF points that seem to have focus above those that do not. The backgrounds in some of your wider full-car shots are out of focus, so the meter will probably give them less weight than the car (and all its sparkly highlights) in the foreground. Again, it is not surprising that you need to add more light, since the background is darker than it might have been with a 5DII.

Didn't know that, either! What happens when you manually focus? Does the camera still try to figure out which areas are in focus, and which aren't, for metering purposes?

At least with my 7D, yes, the camera is actually always running its focus check algorithm. If you manually focus and half-cock the shutter button, you should still get a focus confirmation beep. The camera is not actually trying to focus, but it knows what areas of the scene are in and out of focus.

1160

EOS Bodies / Re: Any thoughts on how the 5d3 will compare on dxo mark to the Nikon D800?

« on: April 03, 2012, 01:40:21 AM »

And afterward, as we have I hope established, downscaling from the higher resolution is no longer limited to the 16,000 photons per pixel. When we are downscaling, we can work in a deeper numerical space, allowing the equivalent of, say, 64,000 photons per pixel without incident. We can normalize the result of the downscaling to the noise floor of 10 photons.

And as a result, should this analysis apply (and please tell me how it doesn't): greater sensor photocell density, while maintaining a relatively constant dynamic range per photocell, will increase the dynamic range deliverable in a given lower-than-native resolution output simply by virtue of increasing the effective headroom by dividing the load onto more photocells.

No?

NO. Ignoring electron gain for the moment, your hardware is still limited to 16,000 photons per well.

Lets say we have an ideal monochrome 32x32 pixel sensor (1024 pixels), with a maximum saturation of 16,384 electrons per well, an electron gain of 1 (one photon = on electron) and a standard deviation of noise of +/-5. If you capture 17,384 photons in the center 16x16 pixels, those 256 wells are fully saturated, registering 16,384 electrons per well. The excess 1000 photons is waste. The diode cannot hold any more electrons, so any additional photon strikes are either reflected, or converted to heat (which, itself, could end up becoming an electron in a neighboring pixel or elsewhere in the electronics, contributing to noise). Now you digitize with a 14-bit ADC. Lets just assume you have a gain of 1, so you get 1024 pixels, the center 256 of which have a maximum value of 16,384 (pure white). The center white pixels are bordered by a basic grayscale gradient faloff, with the outer edge containing pixel values 0 +/-5 (which obviously leads to pixels with values between 0-5.)

Now you want to downsample. Your digitized image has 256 pixels in the center with BAKED IN MAXIMUM VALUES. Lets say we downscale considerably, such that we have a 3x3 pixel image. We average the center 256 pixels into the single center pixel of our 3x3 pixel image. The center pixel is...still pure white. The border of pixels around it become...well, roughly an even gray (the average of pixel values between +/-5 to 15360 differentiated by 1024 levels), with the corner pixels possibly approaching a darker gray more so than the rest, but none actually reaching the +/-5 floor for noise.

Two key points here:

 1. Averaging pixels cannot increase highlight range, so if highlights are blown, they are blown regardless of how big the image is.
  - Assuming you have a 9 pixel 3x3 area full of maximum saturation pixels, sampling them all to produce a single output pixel will always result in a pixel of maximum value.
  - (16384 + 16384 + 16384   +   16384 + 16384 + 16384   +   16384 + 16384 + 16384) / 9 = 147456/9 = 16384
  - The only thing that changes is the physical dimensions of the blown area...which would logically shrink in a downscaled image.
 2. Averaging pixels also cannot increase shadow range, at best it can maintain it, and on average it will likely reduce shadow DR.
  - If you have a 9 pixel 3x3, ranging in value from 0 to 5, sampling them all to produce a single output pixel will rarely result in an output pixel that is zero unless the majority of source pixels are zero.
  - (0 + 2 + 1   +   5 + 2 + 4   +   0 + 0 + 3) / 9 = 17/9 = 1.8889 = 2

Mathematically, once you start averaging pixels with baked-in representations of an analog signal, you cannot gain dynamic range by downsampling (averaging multiple source pixel values together into single output pixels), even with more complex algorithms like bilinear or bicubic filtering (which does more to smooth averaging out over a greater area than anything, incurring an additional cost in terms of detail.) Mathematically, when it comes to dynamic range, you are more likely to LOSE DR (as demonstrated in point 2 above, where you started out with a dynamic range of 0-5, and ended up with a range of 2-2), and at best, you might keep it the same. You will never be able to recover what you lost by not having a deep enough pixel well to start with.

Relating this to DXO:

 1. Screen DR is representative of post-ACD baked-in RAW representations of the analog sensor signal (divided by a possible gain factor).
 2. Print DR is representative of a downsampled RGB image generated from the RAW representation that is itself a representation of the analog sensor signal.

If you want to know what your sensor is capable of, the DXO "Screen DR" measurement is the closest you are going to get to a hardware reading. As for Print DR...mathematically with simple downscaling, you can't gain DR. I am not really sure what print dr represents (I used to think I did, however DXO showing that the D800 gains 1.17 stops of DR simply by downsampling, putting the "Print DR" ABOVE the physical limitation of 14 stops the hardware imposes...has me utterly baffled and finding the measurement rather useless as a result), however it is not actually indicative of what the actual camera HARDWARE is capable of. It is far more indicative of what digital computer algorithms can do with an image once its been converted from analog to digital and turned into a RAW or RGB file, and that really has nothing to do with the camera, and everything to do with software and your desktop computer.

1161

EOS Bodies / Re: Best 5d3 custom function AF point selection quick!

« on: April 02, 2012, 09:39:04 PM »

This post should be stickied! I have the 7D, but never realized this was an option.

1162

EOS Bodies / Re: Are 5DIII users beta testers?

« on: April 02, 2012, 09:34:44 PM »

I dont think we are beta tester.  However it is possible that due to market pressure and Nikon timeline with the D800 that Canon may not have had time to test the mkiii as much as they would have for whatever reason.  Remember that last year some of their energy was away from product dev with all the natural disaster in Japan and Asia...

Either that or the new unit is so complex that it requires more user knowledeg to figure out all possible scenario to best use the camera...

I'd say both are pretty much equal factors. There were certainly a lot of pressures on camera manufacturers due to disasters, however Canon was not the sole victim there. I think the complexity of more advanced technology certainly plays a role. The 7D AF system, for example, is pretty awesome. I upgraded to a 7D from a 450D, and it has taken me a while to fully understand the capabilities of the 19pt AF system. Even understanding all of its capabilities, I personally am still not entirely able to fully realize those capabilities. Learning new technology, especially technology as advanced as a 61pt/41ct AF system with dynamic zones, auto-expanding points, AF-linked metering, etc. will take users time to understand and fully utilize.

1163

EOS Bodies / Re: Any thoughts on how the 5d3 will compare on dxo mark to the Nikon D800?

« on: April 02, 2012, 08:02:46 PM »

Apparently the tech engineers at Canon DSLR were never even let look at it (some method to get 2 stops better DR), the marketing guys and lawyers saw it, more or less said they had no clue what it meant and it seemed dumb more DR and told their employee in the other division to not bother to file a patent on it! Apparently it would have not required any fancy new setups or anything to implement. Maybe it had some flaw, but the marketing droids just tossed it away not even letting the DSLR engineers get a look at it and didn't want to pay a token for a patent filing!

Where the hell do you get this S___, man? That sounds like the biggest bunch of crazy bull you've spouted yet, and there isn't a single reference to back a scrap of it up (Canon Marketing/Legal interfering with Canon Engineering, preventing them from doing their job? WTF kind of inane S___ is that?). I keep trying to get you back to facts and science (your last two posts have completely skirted my direct questions). You just seem to want to rag on Canon, and your starting to really hit the deep end now. If you want to rag on Canon such that they will hear you...call them.


No, Canon's DR is NOT as good as Nikons...but Nikon's is not nearly as good as DXO makes it sound. There aren't 3 stops of difference between the two...at a hardware capability level (derived from native, unprocessed RAW data), there is a difference of 1.77 stops, or about 1 2/3rds of a stop, of DR between the 1D IV and the D800 (and I expect teh 5D III and 1D X to outperform the 1D IV at a hardware level). Ok, so Nikon wins by a third less than two stops...wow? At ISO 400 onward, its all neck and neck, and when you get to really high ISO's, the 5D III seems to be doing considerably better than any SoNikon in the area of SNR and noise quality.

You complain that many Canon users in a Canon form are happy about the improvements Canon HAS MADE, making exclamations about how its all pure fanboyism devoid of any meaningful data to back up their ilbegotten exuberance. You seem to think you have the high road here as well with your complaining about a single issue that exhibits at a single camera setting, and think its the only valid purpose from now until the day Canon finally declares you king of the squeaky wheels and oils the one issue you personally want to complain about.

Flip it all around for a moment dude, and try to see it from the other side. Despite the fact that the 5D III is not some revolutionary headliner in the annals of camera technology designed to wow and jerk tears from camera technotites the world round...despite the fact that they did not fix EVERY SINGLE TINY THING THAT EVERYONE ON EARTH WANTED FIXED...despite the fact that Canon most likely gimped its video to help sell more C300's....despite all that, it is probably the best camera Canon has ever produced. It's relatively reasonably priced (something the 1D X is not, which is why I don't proclaim that as the best), it has Canon's best AF system ever (and potentially the best AF system across brands period once people learn how to use it), it has what is potentially Canon's best sensor (yes, beyond even that of the 1D X, given that it is a very nice rounding of resolution AND high ISO performance), along with an army of ergonomic, functional, and software improvements to make this camera potentially the most well-rounded, well-balanced, broad-reaching camera money can buy. Its not the absolute best at any one thing...but it could very well be the best at just about everything. (Including answering many very long-term, major, and explicitly valid complaints from existing 5D II users...such as its AF system, the greater desire for better ISO and noise quality than continued increases in megapixels, and better metering.)

Nope, its not the DR king. Nope, its not the ISO king. Nope, its not the FPS king. But it'll DO EVERYTHING, SERVICE EVERY NEED, and do it all quite well.

1164

EOS Bodies / Re: My first real shoot with the 5DIII

« on: April 02, 2012, 07:25:32 PM »

First the results:














Now some commentary. This car wasn't running right, so I didn't get to put the AF system through the ringer, but overall I like the camera. That said, I do have some concerns with, of all things, the light meter. I don't have a 5DII, so I can only compare it to my 5DC. I almost always keep the metering in evaluative mode. For some reason, I had to bump the exposure compensation up 1 to 1.5 stops all day long. Even in scenes that aren't contrasty by any means, the light meter seems to freak out whenever it seems any whites, grays, or silvers.

I don't expect miracles from a light meter, and as an old film fart, I still bracket. Even so, for my shooting needs, I find the metering on my 5DC is more accurate. The 5DIII seems overly sensitive to highlights as far as metering is concerned, which could be a good thing depending on what you shoot, but I'm not crazy about it thus far.

The same thing plays out when use a couple of 550EXs off camera for fill or accent lighting. In this arrangement, both the ambient and flash output is underexposed. I was cranking up on the flash exposure compensation 1 to 1.5 stops all day. Metering was inaccurate in both AF and manual focus modes. Me no likey

I'll have to play with the different metering modes more until I pass final judgement, but I'm less than thrilled with it so far. Hopefully it's just user error.

Has anyone experience similar issues?

Those are some pretty fantastic shots, V8! Great examples of the 5D III's performance.

Regarding exposure, I am not sure that anything is wrong. If you count dynamic range being from the darkest pixel to the brightest, there is a LOT of dynamic range in those photos. There are some very bright highlights, particularly off the chrome. I am not surprised that you couldn't capture it all in a single shot without pushing down the shadows. If I had to guess, I'd say...counting the very bright highlights...that there was more than 14 stops of DR in those shots.

Regarding 5D III metering, something you might need to learn to work with is the fact that it is no longer monochrome. Until iFCL and the new 100k RGB metering of the 1D X, Canon metering was monochromatic, it did not take color into account at all. The 5D III uses the iFCL metering sensor, which has blue/green and red/green layers. Canon's own official description of iFCL is here:

Exposure settings: iFCL metering

The EOS 7D SLR features an iFCL 63-zone Dual-layer Metering Sensor. The ‘FCL’ stands for ‘Focus, Colour and Luminance’ and hints at the fact that the metering system not only measures colour and luminance data, but also analyses the data provided by each point of the AF system.

The metering sensor has 63 measurement zones and is a Dual-layer design with each layer sensitive to different wavelengths of light. Electronic sensors in general are more sensitive to red light. This means when photographing subjects with lots of red in them – skin tones for example – the sensor receives a stronger signal as it only detects brightness levels. This can lead to the wrong assumption that there is more light than there really is.

The Dual-layer system overcomes this by having one layer sensitive to red/green light and one layer sensitive to blue/green light. Both these layers measure the light in their respective spectra and the metering algorithm then combines the two to provide an accurate light reading. In this way, accurate exposures can be attained in a wide range of shooting situations and irrespective of the colour of the subject being metered.

Metering algorithm

To work with the iFCL metering sensor, the EOS 7D also features a specific metering algorithm. The EOS 7D always measures focus with all AF points regardless of the selected AF mode. During the exposure reading the EOS 7D looks to see which points, in addition to the selected point, have achieved or almost achieved focus. This information lets the camera know which part of the image is the subject. It then takes metering readings from the zones corresponding to the AF points that have achieved (or almost achieved) focus and combines them with readings from all the other zones. This allows for consistent shot-to-shot exposure, even in complex situations – for example, where there are reflections from a model’s glasses.

I've italicized parts that might be relevant to you. Most importantly is that the previous metering sensors may have assumed incorrectly about how much light was actually available in the scene, as they saw primarily in the red spectrum (monochromatically). The new iFCL metering should be MORE accurate, not less, given that it "sees" full color. It is not surprising that you might have to add more light, for two reasons. One because it meters blue and green now as well as red...silicon is less sensitive to both of those additional colors, and less space is given to red metering. Also for the fact that with a layered system, blue is less sensitive and in the top layer, so the red layer is going to have a certain amount of light filtered out by the layer above, making it less sensitive as well. The lower sensitivity seems like it is by design, though, to produce more accurate, highlight-friendly metering.

Second, the iFCL meter DOES take into account focus, and it will attempt to weight metering around AF points that seem to have focus above those that do not. The backgrounds in some of your wider full-car shots are out of focus, so the meter will probably give them less weight than the car (and all its sparkly highlights) in the foreground. Again, it is not surprising that you need to add more light, since the background is darker than it might have been with a 5DII. I am not entirely certain flash is the ideal solution, though...as that is going to change the lighting characteristics of the car as much (if not more) than anything else, and the way iFCL weights metering....you might just make the discrepancy between dark backgrounds and bright foregrounds worse.

1165

EOS Bodies / Re: Are 5DIII users beta testers?

« on: April 02, 2012, 07:05:39 PM »

I was wondering why the 5DIII came out BEFORE the 1DX camera...

Because Canon is a publically-traded company and wants to show a profit, and the 5DIII will be much more profitable than the 1D X, based on volume.

Still, implicit in your question is, "Was the 5DIII released before it was ready?"  Possibly - there are known issues (acknowledged by Canon) with both the 5DIII and the DPP update that was required to support it.

I think thats certainly part of it, however I think a lot of Canon's reputation, particularly on the AF front, rides on the performance of the 1D X. I think a more significant part of the 1D X delay is due to the fact that Canon knows they need to perform at least on-par with Nikon's 51pt AF system, and to really make any additional headway in that arena, they need to demonstrate that it is more capable than Nikon's system.

I think you were spot-on in one of your other answers to another thread...that Canon probably cannot add adequately competitive f/8 AF without improving the design of the one used in the 5D III, as its not just a software problem. You have to have phase-detection strips sensitive enough for f/8. I think Canon would have preferred that the 1D X hit the streets far enough in advance of the Olympics such that users would have some time to get used to the new AF system. As things stand now, I think its less about profit margins and more about reputation, and even that will be on the line soon if they can't deliver competitive AF in the 1D X by the time the Olympics start.

1166

EOS Bodies / Re: Canon hurry up! Nikon's face-detection & Sony's Exmor sensors are killing us!

« on: April 02, 2012, 04:34:52 PM »

So, Canon's iFCL metering system sees color in the same way as a dog or an old-world monkey sees color - a dichromatic system, not a trichromatic system like the 1D X and us humans use...

Does this distinction have any real-world implications in the accuracy and/or quality of the AF system?

I wouldn't say it has too many real-world implications, probably even less than a biological system.

In human vision, we have two separate "poles" of color sensitivity: blue/yellow and green/magenta. Because of the nature of how our trichromatic sight works, we cannot actually sense both blue and yellow or both green and magenta at the same spatial point at the same moment. If you try, the eye & brain will compensate by oscillating between sensing one color then sensing the other (http://io9.com/5710434/train-yourself-to-see-impossible-colors)...however you will not actually see green (which according to color theory is what you should get when blending blue and yellow). This is generally not a problem, as we have two separate poles of color sensitivity (increasing "color sensitivity resolution"), and our eyes "refresh" some 500 times a second. Dichromatic vision has only a single pole, and therefor has lower color sensitivity resolution. If you had dichromatic vision, you could either sense red or blue, but not both at the same time.

Now, the iFCL sensor is not a biological system, its an electronic system. Silicon is semitransparent to various wavelengths of light. So long as the upper layer is blue sensitive, there is nothing to prevent an electronic sensor from simultaneously sensing blue-green and red-green at the same time. Such a sensor probably still doesn't have as high a color sensitivity resolution as a trichromatic system would since your sensing blue-green and red-green rather than blue, red, and green, but its probably better than a biological dichromatic system.

1167

EOS Bodies / Re: Any thoughts on how the 5d3 will compare on dxo mark to the Nikon D800?

« on: April 02, 2012, 04:10:04 PM »

@LetTheRightLensIn:

Your still missing the point. So lets use an example to demonstrate. Say you shoot a scene with 14.4 stops of DR, and blow the highlights, since the camera is only capable of 13.23 and your trying to preserve as much shadow detail as possible. You THINK the camera is capable of capturing all of the DR in the scene, because you believe what DXO claims about the D800's DR. However, once you get to it, you realize no amount of POST-PROCESS SPATIAL AVERAGING is going to RECOVER those blown highlights. They were blown well before it ever got to the point of averaging them down...they were blown in the photodiode, amplified in the sensor, converted at maximum level by the ADC. Those pixels hit their maximum saturation and then some...by 1.17 stops (2.25 times more than the sensor is capable of.)

Do you agree or disagree with that point?


Lets agree that downsampling can produce a result that is a perceptual improvement over a similar image from another camera at the same dimensions (because on that point, I do agree!) When you downsample, you average noise across pixels and therefor lose noise, you sample detail from multiple pixels into fewer pixels and lose resolution and detail, you collapse more information into less total area to produce an image of smaller width and/or height so you lose pixel density at a similar print size. Etc. etc.

Downsampling incurs a LOSS OF INFORMATION, not a gain of information. The only improvement, the only gain, is on a perceptual basis, in comparison with other images that started out at smaller sizes. Since a downsampled image is based on a similar image of larger size, every pixel in the output image has more information to work with than the source image...however the grand total amount of information remains the same! There is no increase of data in the output image, it simply makes more effective use of the information that was available. An increase in DR cannot actually occur, because if the original source information contains blown highlights, no amount of multisampling or averaging can change that.

1168

EOS Bodies / Re: digitalrev.com D800 vs 5D3

« on: April 01, 2012, 08:06:01 PM »

I always love the DigitalRev guy. Funny, quirky, bit of a bikini-clad woman -izer, er...chaser... I also think he straddles the Nikon/Canon fence well in his comparisons, although he does tend to be Nikon-biased.

As for the video and the results...near the end, when he was shooting in low light, two things caught my attention. For one, the 5D III seems to have FAR better color!! The D800 appeared very washed out and kind of dull, but the 5D III color was brilliant! When he made his comments about sharpness I became a bit curious. Both images were downscaled to fit into a 1080p video...NEITHER of them should have really shown any difference in sharpness with that much downscaling, yet the 5D III did appear a touch "soft". I wonder if that was a bit of "Nikon-biased" editing? I've seen other sample 5D III shots that are tack sharp, regardless of the fact that they are lower res than D800 shots....eh, curious, curious.

1169

EOS Bodies / Re: DXO vs Reality

« on: March 31, 2012, 07:16:55 PM »

But anyone, who does not posses some advanced knowledge about AD converters, Fourier transform, digital imaging and such things should not care them. You only fool yourself, when you compare numbers without knowing their meanings. Worse, when you argue about numbers without knowing their meaning, you fool others too.

That, right there, pretty much sums up the problem with DXO quite perfectly: The exact meaning of their numbers are not fully known!! Thats my entire complaint about Print DR...we don't know what the hell it really is, exactly how it is derived, and exactly what mathematical and procedural algorithms are applied to images when scaling to their 8x12 print size. Worse yet, we don't know if they use a consistent approach to that process, and with the results of the D800, whether DXO uses a "consistent approach" is exactly why they are in the crosshairs.

Now, I personally do understand how ADC's, fourier transforms, digital imaging, color processing and color spaces, color fidelity and color space conversions, spatial frequencies/MTF, and the physical nature of light work, and I know it pretty damn well. I may not be a DXO Labs "scientist", but I do understand how those things work. Despite that, I STILL find the numbers DXO produces to be useful ONLY WITHIN the context of DXO. Without explicit details about how every one of their tests is done (we only have vague details and rolled up mathematical formulas, etc.), DXO numbers don't really mean anything in the real world.

So yeah, no one is really truly qualified to use DXO numbers in any meaningful context...and that is also exactly the problem, especially when people put too much weight on their results. They may be consistent, but if D800 Print DR is telling to any degree, they are seeming more and more to be consistently useless.

1170

EOS Bodies / Is the Nikon 51-pt AF system actually capable of f/8??

« on: March 31, 2012, 06:10:03 PM »

While digging around the bowls of the internet looking for solid information on Canon and Nikon AF systems, I came across Nikons own official page on their 51-pt AF system. I found the following blurb (from http://www.nikonusa.com/Learn-And-Explore/Nikon-Camera-Technology/ftlzi4pn/1/51-Point-Autofocus-System.html):

With the new Nikon D4, the AF maintains the power of the five cross-type sensors in the center as long as the combined open aperture value is below f/8.

I've emphasized the most important part. The Nikon 51-pt AF system works with the five cross-type sensors in the center as long as the maximum aperture is BELOW f/8? Where exactly does Nikon say their AF system supports f/8 autofocus? Where exactly is the information that declares the D800 or even D4 capable of even center-point AF with a maximum aperture of f/8?

For all the hullabaloo about how the 5D III and 1D X are inferior to the Nikon offerings...I'm not sure there is actually any evidence to support the idea that Nikon cameras can AF AT f/8. That would at best put them on par with Canon's new AF, and they are certainly trailing behind in the area of higher-precision cross-type points (15 with Nikon's 51pt AF system, vs. 41 with Canon's 61pt AF system.)

So...where exactly is f/8 AF for Nikon?