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Author Topic: Lloyd Chambers compares D3x - 5DKII shadow performance  (Read 21531 times)
Ray
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« Reply #20 on: January 24, 2009, 08:11:45 PM »
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Quote from: JohnKoerner
It completely eclipses its true competitor, the D700.

Not quite, Jack. I think you might be in danger of becoming a Canon fanboy   .

Lloyd claims his tests are pretty much in line with DXOmark's results. Below is DXO's DR page comparing these two cameras.

Panopeeper would probably claim that the graph at the top is more indicative of the true DR of these cameras, showing a 2/3rds stop DR advantage for the D700. However, when both images are downsampled for an 8x12" print at 300 ppi, the DR is about the same for both cameras, although the D700 still retains about 1/3rd of a stop advantage at base ISO.

However, the 5D2 certainly eclipses the D700 regarding resolution.

You should also not forget that some cameras have other features that contribute to image quality in addition to basic sensor performance. I'm particularly impressed with the D700's ability to autobracket up to 9 consecutive shots with a choice of exposure interval of 1/3 to 1 stop. This feature is tremendously useful for merging to HDR to increase DR. In my experience a lot of the criticism of the HDR process is due to people trying to merge an inadequate number of shots with an exposure interval that is far too great for the 2 or 3 shots taken.

Another tremendously useful feature of the D700 is the facility to set auto ISO in manual mode. You choose the aperture and the shutter speed. The camera chooses the ISO for correct exposure. It has always puzzled me why Canon have not bothered to provide such a facility considering they have provided cameras with low noise at high ISO for a number of years now.

A lot of photography is about capturing the moment. One often simply doesn't have time to mess around adjusting ISO in order to get an adequate shutter speed. Controling both the aperture and shutter speed can be critical for a good shot.

[attachment=11087:DXOmark_5d2_v_D700.jpg]
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« Reply #21 on: January 24, 2009, 10:32:34 PM »
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Quote from: Ray
The camera chooses the ISO for correct exposure. It has always puzzled me why Canon have not bothered to provide such a facility considering they have provided cameras with low noise at high ISO for a number of years now
Perhaps Canon do not want to sell to suckers? Perhaps they understand, that every stop in ISO reduces the DR by half stop (in average)?
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« Reply #22 on: January 25, 2009, 01:19:29 AM »
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Thanks Ray.  To me the most important is to compare these two "Full SNR" charts.  The charts you posted were "2D" (SNR - ISO at 18% gray level), which are cross sections of these two "3D" (SNR - ISO - Gray Level) charts that tells you much much more, such as linearity.

Since they are produced by the DxO site as "Fusion Charts" there is no labels.  The left is D3x and the right is 5DII.

Thanks,
Leping
« Last Edit: January 25, 2009, 01:21:04 AM by LEPING » Logged

NikosR
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« Reply #23 on: January 25, 2009, 01:21:33 AM »
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Quote from: Panopeeper
Perhaps Canon do not want to sell to suckers? Perhaps they understand, that every stop in ISO reduces the DR by half stop (in average)?

Nonsense. Everything is a compromise. I don't see how offering an option (you don't HAVE to use Auto ISO) is anything but a good thing. Why don't you go over to sportsshooter.com and collectively call the people over there 'suckers'. See what their reaction will be...
« Last Edit: January 25, 2009, 01:23:26 AM by NikosR » Logged

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« Reply #24 on: January 25, 2009, 06:02:46 AM »
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[quote name='LEPING' date='Jan 23 2009, 08:55 PM' post='254029']

DxO Measured SNR (Signal to Noise Ratio) in dBs:

Gray   Camera  +---------------  ISO  ----------------+
Level  Model    | _100   _200   _400   _800  1600  3200  6400 |
-----  -----  | ----  ----  ----  ----  ----  ----  ---- |
0.1%   _D3x__  |  14.5  11.0   _6.5  _2.0    ----     ----     ---- |
0.1%   _5DII_   |  _7.0   _6.5  _5.5  _3.5    ----     ----     ---- |
0.1%   _D700_  |  _N/A   10.5  _9.0  _6.5   _1.5    ----     ---- |

1.0%   _D3x__  |  26.5  23.0  20.0  16.5  12.5   _9.0  _4.0 |
1.0%   _5DII_   |  24.5  23.0  21.0  18.0  15.0  11.0  _7.0 |
1.0%   _D700_  |  _N/A  26.5  23.5  21.0  17.0  12.5  _7.5 |


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0.1% At ISO100 More than 7dB of difference      
Very, very strange      

Thierry
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dchew
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« Reply #25 on: January 25, 2009, 06:55:23 AM »
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Lloyd says this on the public site:
"The examples were “pushed” using the Photoshop CS4 Highlights/Shadows feature. The amount used is equivalent to 3-4 stops, which is not much more than the light falloff with many lenses shot at wide apertures (~3 stops combined optical and sensor vignetting). Combined with features like Active D-Lighting, Peripheral Lighting correction, etc, it is perfectly realistic to “push” the shadows 2-3 stops as a matter of routine, not to mention high-contrast scenes that require very dark tones in order to record the highlights." - Lloyd L. Chambers

Really?  3 stops for vignetting?  I've got an "old" 5D, and I don't think even my 24-105 f/4L is that bad.  Sure, it's got relatively large photosites, but...

I can't remember the last time I pushed shadows 3-4 stops, (or 2-3), let alone "as a matter of routine."  In fact usually I nudge up the blacks combined with some fill light.  I'm not saying it wouldn't be nice to have the option, but the frequency of need just isn't in my experience.  Or am I falling into the "I never need that (because I don't have it) trap?

Dave Chew




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Ray
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« Reply #26 on: January 25, 2009, 08:25:20 AM »
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Quote from: Panopeeper
Perhaps Canon do not want to sell to suckers? Perhaps they understand, that every stop in ISO reduces the DR by half stop (in average)?

Which would you prefer? A sharp image at the sacrifice of a stop of DR, or a blurry image with lovely clean shadows?

One should also consider, when a camera has exceptionally good dynamic range, as the D700 has, there's some to spare with most scenes.

If the DXO test results, as shown in graph form on their site, are accurate, then the D700 at the actual and tested ISO of 400, has the same DR as the 5D2 at the real and tested ISO of 73 (base ISO); and that's after downsampling to an 8"x12" print size. If we use your standard, the DR of the 5D2 at ISO 73 is equal to the DR of the D700 at ISO 651 which allows for more than 3 stops faster shutter speed at the same aperture whilst still maintaining the same DR as the blurry image from the 5D2 at ISO 73.
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« Reply #27 on: January 25, 2009, 11:24:45 AM »
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Lloyd just reported that D3x is also much cleaner (no hot pixels or streaking) at long exposures (30 seconds and over) WITHOUT dark frame subtraction ("Long Exposure NR") than the 5DII, which he says come with a "dirty" sensor.

http://diglloyd.com/diglloyd/2009-01-blog....124LongExposure

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digitaldog
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« Reply #28 on: January 25, 2009, 11:45:21 AM »
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Quote from: NikosR
Nonsense. Everything is a compromise. I don't see how offering an option (you don't HAVE to use Auto ISO) is anything but a good thing. Why don't you go over to sportsshooter.com and collectively call the people over there 'suckers'. See what their reaction will be...


I fully agree. We all know the downside to pushing ISO. There's no free lunch. As Ray said perfectly, I'd rather have a sharp grainy, lower DR image then no image at all. When I go into a dim, naturally lit scene and have no intention of using ugly on camera flash versus nice but dim natural light, I'd far prefer the later and will accept the quality loss. That's why I dropped the $$ on a 35mm 1.4. In just a few weeks of shooting, I'm very pleased at the 5DMII versus the 5D it replaces in terms of its extended ISO.
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Panopeeper
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« Reply #29 on: January 25, 2009, 10:19:46 PM »
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The DxO results as well as the "professionally done" tests of Lloyd have been too suspicious for me to let them pass unchecked. Unfortunately, I can not make measurement on their raw images, for I don't have them. However, I have used the raw images published by Imaging Resources and made objective, documented measurements based on the non-demosaiced raw data.

The result proves, that the claim "two stops higher DR than the 5D2" is *ridiculous*, like some other claims. In fact, the DR of the D3X is max. 0.5 EV greater than that of the 5D2 at ISO 100. AT ISO 200 they are virtually equal, and at ISO 400 the 5D2 is already better.

A side note: I find it amusing, that someone makes a "professional test", among others involving ISO 50, obviously not knowing, that neither of the cameras has ISO 50.

Independently of the unseriosity of those claims, the D3X seems to be a great camera, according to what I see in the images (I am sure the other aspects do not negate this). Having a 0.5 EV advantage over Canon's best sensor of the moment is something Nikon can be proud of.

Anyway,

I challenge anyone to post raw files proving those claims.
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Gabor
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« Reply #30 on: January 25, 2009, 11:48:21 PM »
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It's hard for anyone interested to argue with you when you don't provide any supporting evidence for your claims or explain your methodology.

BTW DxO purport to have measured the following max DR values for the two cameras at their ISO 100 setting (measured before resolution normalisation):

5DII: Claimed ISO 100, Measured ISO 73, DR 11.16 EV
D3X:  Claimed ISO 100, Measured ISO 78, DR 12.84 EV

At ISO 400 setting:

5DII: Claimed ISO 400, Measured ISO 285 (!!), DR 10.92EV
D3X:  Claimed ISO 400, Measured ISO 337, DR 11.25EV

The 5DII is measured as having equal DR to the D3x near measured ISO 564 ( 5DII claimed ISO 800!!) with DR about 10.66EV. From then on (higher than measured ISO 564) the 5DII exhibits slightly better DR.

They say they measure DR from well saturation to S/N=1 (a noise floor which btw is probably useless from a photographic point of view but correct from an engineering point of view)

Any evidence you provide to counter DxO claims should counter the above DxO findings.
« Last Edit: January 26, 2009, 12:25:32 AM by NikosR » Logged

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« Reply #31 on: January 26, 2009, 04:41:10 AM »
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Hi,

Just a comment. Lloyd Chambers's tests are based on converted images and the choice of tools he use of course matters. I don't have an issue with that approach.

Your testing is based on "raw"-data, so your results tell a story which is different. Your approach tells us what information is available in the raw file, that's a valid approach and IMHO a more interesting one.

Regarding the DxO results I'm puzzled. Mr. Leping had links to these curves from DxO which I find quite revealing even if I cannot explain the difference.
http://luminous-landscape.com/forum/index....st&id=11093 (Nikon D3x)
http://luminous-landscape.com/forum/index....st&id=11094 (Canon 5DII)

My observation in the DxO figures is that SNR drops rapidly at 0.1% gray scale whereas then Nikon curves have a slower and more natural drop.

Best regards
Erik



Quote from: Panopeeper
The DxO results as well as the "professionally done" tests of Lloyd have been too suspicious for me to let them pass unchecked. Unfortunately, I can not make measurement on their raw images, for I don't have them. However, I have used the raw images published by Imaging Resources and made objective, documented measurements based on the non-demosaiced raw data.

The result proves, that the claim "two stops higher DR than the 5D2" is *ridiculous*, like some other claims. In fact, the DR of the D3X is max. 0.5 EV greater than that of the 5D2 at ISO 100. AT ISO 200 they are virtually equal, and at ISO 400 the 5D2 is already better.

A side note: I find it amusing, that someone makes a "professional test", among others involving ISO 50, obviously not knowing, that neither of the cameras has ISO 50.

Independently of the unseriosity of those claims, the D3X seems to be a great camera, according to what I see in the images (I am sure the other aspects do not negate this). Having a 0.5 EV advantage over Canon's best sensor of the moment is something Nikon can be proud of.

Anyway,

I challenge anyone to post raw files proving those claims.
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« Reply #32 on: January 26, 2009, 09:27:05 AM »
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Quote from: dchew
Lloyd says this on the public site:
"The examples were “pushed” using the Photoshop CS4 Highlights/Shadows feature. The amount used is equivalent to 3-4 stops, which is not much more than the light falloff with many lenses shot at wide apertures (~3 stops combined optical and sensor vignetting). Combined with features like Active D-Lighting, Peripheral Lighting correction, etc, it is perfectly realistic to “push” the shadows 2-3 stops as a matter of routine, not to mention high-contrast scenes that require very dark tones in order to record the highlights." - Lloyd L. Chambers
Now if I want to push shots I use the best RAW converter for the files and optimise there, not open in PS and use Shadows/Highlights. Or is he doing that as well? Even so.....!

The only way to realistically test cameras in my view is to use the best practice techniques for each camera, such as the best/most likely to be used RAW developer for those files and then look at the results - that has far more meaning in the real world than using each one identically, but unrealistically

I saw some comparison shots in a UK Camera mag the other day and the 5DII files looked way inferior to the D3x files but they also looked underexposed in comparison. So not surprising really.
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« Reply #33 on: January 26, 2009, 09:58:28 AM »
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Quote from: LEPING
This is mostly unrelated.  And I do understand not everyone uses a Mac.  But for those who do, I just found Lloyd's (totally free) comprehensive guide for optimizing Mac performance, especially running Photoshop and other photographic applications (such as the Canon DPP).
http://macperformanceguide.com/index.html
He does talk some ignorant tosh though. For instance the very first thing he posts is this.

"Ergonomics: the Mac Pro is about as quiet as it gets, and all its memory, hard drives, etc are easily accessible without tools. It is esthetically pleasing also, fitting into even “hip” offices, especially in Redmond.
Massive, fast storage: The Mac Pro accommodates four internal drives for 6TB of internal storage (4 X 1.5TB) , and with a special bracket as much as 9TB, all using the built-in SATA connectors. "


Adding two extra hard drives to take my MacPro up to six from the normal max of 4 bays internally, involved removing the DVD drive and some other fiddly bits to then spend quite a while threading SATA cables through awkward gaps to plug into the obscured extra two SATA ports, which most people are unaware of. I had to also hack the end connectors of the SATA cable to allow it to fit in the sockets. I now also have no room for DVD writer, unless I use an external one.

My PC tower has 9 drives in it and 2 optical drives and isn't any bigger than the MacPro. Which is indeed a nice quiet box, except for the dreadfully loud DVD writer and was another reason I removed it. But it's decidedly limited and fiddly if you like lots of HDs. I  have another 5 External drives [4 eSATAs] with loads of bulky cables and power adaptors making the neat MacPro look a lot less tidy and I still need more HDs attached . It would be a lot better if the MacPro was a bit more professional and had some options [a dirty word at Apple] like a slightly taller case if required with 2 rows of 4 HD caddies.

Going a little OT here sorry. But Lloyd doesn't make me think too highly of his 'scienticfic' testing when he gets such basic facts wrong and doesn't even know if you can run Win64 on a Mac [you can]. He just reads like a fanboi and would treat his camera tests with some scepticism as a result.
Shame as some of his other advice on the subject is actually very good.
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« Reply #34 on: January 26, 2009, 10:45:39 AM »
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Quote from: ErikKaffehr
My observation in the DxO figures is that SNR drops rapidly at 0.1% gray scale whereas then Nikon curves have a slower and more natural drop.

The knee in the SNR curves is the crossover between the noise being dominated by electronic read noises at the low end to being dominated by photon shot noise at the high end.  The relative constancy of the slope of the curves across the dynamic range is an indication that the read noise is quite low at low ISO in the D3x.  This may be a consequence of the column-parallel readout architecture of the Sony chip; the D300 has a similar property, though not quite so pronounced.
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« Reply #35 on: January 26, 2009, 12:01:34 PM »
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Exactly.  Please read the DxO documentation for the three noise characterization zones, better not only this summary but all the tabs in the "Noise Characterization" topic.

If there were no read noise, both the shadow and the mid-tone zone curves would go by the same slope, 6dB per EV, so that there is no "knee".  Only D3x came close to the ideal behavior, while all the other sensors fall short more or less, if you check their "Full SNR" curves out one by one.

These curves also enable to derive DR measures at any SNR definitions above 1:1 (0dB).

http://www.dxomark.com/index.php/eng/Techn...ization/Summary

Quote from: ejmartin
The knee in the SNR curves is the crossover between the noise being dominated by electronic read noises at the low end to being dominated by photon shot noise at the high end.  The relative constancy of the slope of the curves across the dynamic range is an indication that the read noise is quite low at low ISO in the D3x.  This may be a consequence of the column-parallel readout architecture of the Sony chip; the D300 has a similar property, though not quite so pronounced.
« Last Edit: January 26, 2009, 12:06:44 PM by LEPING » Logged

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« Reply #36 on: January 26, 2009, 12:19:06 PM »
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What you have said is that basically Lloyd was right and there are solid recommendations in his Mac performance site, but you need more hard drives beyond the Mac Pro's capacity of 7, and you know things like the tricks to run Win64 on a Mac Pro he didn't.

Congratulations for being such a elite computer user requiring at least two 4-HD raws inside your desktop machine, but isn't that true for the most of the rest (needing less than 7 drives, etc.) there are still things to learn from the site, such as how to separate data and applications, and how to set up a Photoshop specific scratch volume or a RAM disk to speed things up?  And is it true for them the Mac Pro is still quiet and tidy?  I do competitive photography, but I do not happen to know that much about computer.  Is this makes me disqualified to express my findings here in a photography forum, or my own blogs?

Seagate insisted their firmware fixes for the problematic 7200.11 drives can only be applied on a PC.  I searched online, found the procedures, and had no problem to boot my Mac Pro from the ISO CD-ROM volume to flash all my 1.5T drives successfully (since now a days Macs are indeed just PCs and they can boot into DOS).  Does Seagate's ignorance makes them disqualified to make hard drives?

Lloyd Chambers also offers free drive and memory stress test software (Disk Tester, etc.), that have been used in many professional review sites.

Quote from: jjj
He does talk some ignorant tosh though. For instance the very first thing he posts is this.

"Ergonomics: the Mac Pro is about as quiet as it gets, and all its memory, hard drives, etc are easily accessible without tools. It is esthetically pleasing also, fitting into even “hip” offices, especially in Redmond.

Massive, fast storage: The Mac Pro accommodates four internal drives for 6TB of internal storage (4 X 1.5TB) , and with a special bracket as much as 9TB, all using the built-in SATA connectors. "


Adding two extra hard drives to take my MacPro up to six from the normal max of 4 bays internally, involved removing the DVD drive and some other fiddly bits to then spend quite a while threading SATA cables through awkward gaps to plug into the obscured extra two SATA ports, which most people are unaware of. I had to also hack the end connectors of the SATA cable to allow it to fit in the sockets. I now also have no room for DVD writer, unless I use an external one.

My PC tower has 9 drives in it and 2 optical drives and isn't any bigger than the MacPro. Which is indeed a nice quiet box, except for the dreadfully loud DVD writer and was another reason I removed it. But it's decidedly limited and fiddly if you like lots of HDs. I  have another 5 External drives [4 eSATAs] with loads of bulky cables and power adaptors making the neat MacPro look a lot less tidy and I still need more HDs attached . It would be a lot better if the MacPro was a bit more professional and had some options [a dirty word at Apple] like a slightly taller case if required with 2 rows of 4 HD caddies.

Going a little OT here sorry. But Lloyd doesn't make me think too highly of his 'scienticfic' testing when he gets such basic facts wrong and doesn't even know if you can run Win64 on a Mac [you can]. He just reads like a fanboi and would treat his camera tests with some scepticism as a result.
Shame as some of his other advice on the subject is actually very good.
« Last Edit: January 26, 2009, 12:39:37 PM by LEPING » Logged

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« Reply #37 on: January 26, 2009, 02:42:57 PM »
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Quote from: ErikKaffehr
Regarding the DxO results I'm puzzled
The problem is, that they do not publish the images and the exact measurements they have taken; thus one can not reconstruct their results and critiques can not be qualified.
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« Reply #38 on: January 26, 2009, 02:46:21 PM »
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I created a demonstration for the support of my statements re the D3X and 5D2 evaluations.

a. I used the raw files from Imaging Resources, because they are suitable (more or less), and I don't have any others suitable. They were recorded in 12bit mode (why on earth); this would pose a problem *if* the DR of the D3X were really so large; however, it is not.

b. These shots are not exposed as low as I would prefer them to be. Therefor I used only the red channel, which is more than 1 EV darker than the green and about 0.8 EV darker than the blue on grey patches (under the current illumination).

c. I selected only such patches, which are enough clean and evenly illuminated; not like this: http://www.panopeeper.com/Noise/D3Xvs5D2/C...yTestSheet.GIF

d. It is not necessary to have any high exposure when measuring the DR; only the dark end is interesting.

e. The 5D2 has a small disadvantage in the measured ISO (less than 1/3 EV); this affects the noise characteristics, but not the dynamic range. The test images have compensated for that difference by the shutter time.

f. I highlighted with red one or two numbers over the image. The last number in the upper raw per color group (identified as DR) represents the average pixel intensity on the selection, measured from saturation downwards. The last number of the color group in the second row (identified as NP) is the noise in the salection, measured as standard deviation, expressed as percentage of the average intensity. 100 times the reciprocate of this number is the SNR. NOTE: this number has nothing to do with "stop".

Example: in http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00100_b.GIF the intensity is -8.62 EV, the noise is 19.48%, which corresponds roughly to SNR=5.

g. The D3X raw pixel values are not linear (nor are the 5D2's, but they are compensated for), therefor the very dark patches appear to be darker than they really are; I have not highlighted them.

Finally, the measurements:

ISO 100

a. Medium dark patch: the intensities are virtually identical: -6.92 EV vs -6.97 EV. The D3X patch is cleaner; noise: 6.59% vs. 7.56% (very low, visually not perceivable).

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00100_a.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00100_a.GIF

b. Dark patch: the advantage of the D3X is now visually perceivable; the noise is only 15.4%, vs. 19.48% of the 5D2, at the intensity -8.62 EV.

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00100_b.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00100_b.GIF

The question is, how much difference in EV does this difference in noise represent. To find it out, I searched for a patch in the same 5D2 image with closely comparable noise. I found one with noise 15.55% (very close to the 15.4%), at the intensity -8.29 EV. This means, that the 5D2 requires 8.62-8.29=0.33 EV more light to have the same level of noise as the D3X. Measurements on different spots show like or slightly larger difference, and it can be somewhat greater in even darker spots.

http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00100_c.GIF

Here it would be interesting to see darker patches. Unfortunately, the community of this forum is more interested in flaming than in providing usable raw files.

ISO 200

The difference is gone on the medium dark patch (actually, the D3X sghows slightly higher noise, but negligable).

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00200_a.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00200_a.GIF

The darker patch shows a slight advantage of the D3X:

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00200_b.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00200_b.GIF

ISO 400

The 5D2 has clearly lower noise than the D3X, on the darker patch as well:

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00400_a.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00400_a.GIF;

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00400_b.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00400_b.GIF

ISO 800

The gap is widening to the advantage of the 5D2:

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00800_a.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00800_a.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO00800_b.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO00800_b.GIF

ISO 1600

The D3X is clearly not a high ISO camera.

http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO01600_a.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO01600_a.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/N...ISO01600_b.GIF
http://www.panopeeper.com/Noise/D3Xvs5D2/C...ISO01600_b.GIF

UPDATE: semicolons removed from the image URLs
« Last Edit: January 26, 2009, 04:36:03 PM by Panopeeper » Logged

Gabor
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« Reply #39 on: January 26, 2009, 03:17:19 PM »
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Quote from: LEPING
If there were no read noise, both the shadow and the mid-tone zone curves would go by the same slope, 6dB per EV, so that there is no "knee".  Only D3x came close to the ideal behavior, while all the other sensors fall short more or less, if you check their "Full SNR" curves out one by one.

These curves also enable to derive DR measures at any SNR definitions above 1:1 (0dB).

http://www.dxomark.com/index.php/eng/Techn...ization/Summary
I see now what you meant by 3dB/EV on the D3x.

There is something I always wonder about the Full SNR curves in DxO Mark, even if I consider them very valid conceptually:

1. What does the sign 'Gray scale' in the X axis mean? Doesn't the X-axis on those plots represent any undemosaiced and unprocessed RGB RAW values?
2. The 100% mark in the right end, is camera's sensor saturation point, or the maximum RAW value in the sensor's bit scale? I mean: for the 5D a 12-bit camera, the 100% represents the value 4095 or the real saturation point of that camera, which is 3692 at ISO100?

BR
« Last Edit: January 26, 2009, 03:19:38 PM by GLuijk » Logged

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