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Author Topic: DxOMark Sensor Performance: Nikon vs. Canon  (Read 126977 times)

Orangutan

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #75 on: September 19, 2012, 11:05:33 PM »
I don't believe it's correct to say that 4 are combined into 1.  The de-mosaicing is an interpolation algorithm that uses the values from adjacent pixels to estimate the intensity and color of each pixel.  The demosaicing algorithm doesn't do any binning in the way you suggest. 

I didn't mean to suggest binning at all; demosaicing is (presumably) a complex algorithm.  I was making a simple point: if you take data from 4 photosites, each having 14EV of DR, you can demosaic in a way that gets you more than 14EV DR in the resultant pixel.  It's not guaranteed that you would, but it's possible. 


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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #75 on: September 19, 2012, 11:05:33 PM »

Meh

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #76 on: September 19, 2012, 11:42:36 PM »
I don't believe it's correct to say that 4 are combined into 1.  The de-mosaicing is an interpolation algorithm that uses the values from adjacent pixels to estimate the intensity and color of each pixel.  The demosaicing algorithm doesn't do any binning in the way you suggest. 

I didn't mean to suggest binning at all; demosaicing is (presumably) a complex algorithm.  I was making a simple point: if you take data from 4 photosites, each having 14EV of DR, you can demosaic in a way that gets you more than 14EV DR in the resultant pixel.  It's not guaranteed that you would, but it's possible.

I was addressing only the first line of your statement where you said about demosaicing that 4 pixels are made into one RGB pixel which is not correct the way you wrote but fair enough if that's not what you meant.

Binning pixels still doesn't result in greater bit-depth though because that is limited by the ADC.  Each pixel can only be assigned 14-bit luminosity regardless of how many electrons are in the well.  For example some FF sensors have photosites with say 50,000 electron full-well capacity.  14-bit addressing only requires about 16,000 electrons so you have about 3 electrons per level.  Binning 4 pixels gives you more pixels but you still only have 14-bit addressing in the ADC.

But I'll leave it there since it's been a long time since I've been involved with that kind of thing and may already not be explaining it quite right.

LetTheRightLensIn

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #77 on: September 20, 2012, 02:14:25 AM »
Hi,
   IMHO, DxOMark is not testing the sensor, but the camera itself because they use the RAW file produce by the DSLR (they didn't remove the sensor from the body and test, right?) and if the RAW file produce by the camera is not the RAW data, then it's not testing the sensor and the sensor compare between brands is somehow not valid. I believe all RAW file is not RAW data and Nikon RAW file are well know for it.

   Anyway, I was wondering how do Nikon D800 and D600 get a dynamic range of more than 14EV when there is only 14-bit of data? Compress the dynamic range or non-linear data?

   Have a nice day.

1. Why would they test the sensor removed from the camera? Can you get a picture out of a bare sensor? It's the RAW file that the user gets to use. Most of DSLR RAWs are pretty RAW under standard conditions and settings (Nikon does cook books starting with longer, but not long enough IMO, exposures, etc.).

2. They get more than 14EV on the normalized comparison, it's normalized to 8MP so with 36MP to play with there is a lot of room to get the extra bits after normalization there.

sarangiman

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #78 on: September 20, 2012, 02:53:49 AM »
2. They get more than 14EV on the normalized comparison, it's normalized to 8MP so with 36MP to play with there is a lot of room to get the extra bits after normalization there.

Exactly. Say you have 14EV DR at the pixel level; i.e. you've perfectly matched your ADC to the DR attainable at the pixel level (e.g. saturation capacity = 16,384 e- & read noise = 1 e-). But say this is for a 100MP sensor.

When you go to make a 4" x 6" print of that 100MP file, you'll be doing a lot of downsizing for a 300dpi printer. That process of downsizing will reduce noise. Therefore you will be able to lift shadows more while still producing an acceptable print. Therefore shadows with a pretty low SNR may suddenly become 'acceptable' the viewer of the 4x6 print.

Yada yada... that's how you get more dynamic range via normalization.

Although I still have a hard time wrapping my head around it.

Because if your SNR is ever <1, you're not going to magically recover the signal by resampling... resampling would only bring you closer to the average of the noise as SNR approaches 0.

But for more reasonable definitions of DR (e.g. Bill Claff's 'PDR' that defines the lowest acceptable SNR as 20), normalization expanding DR makes perfect sense.

messus

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #79 on: September 20, 2012, 03:48:03 AM »
Canon has some catching up to do with respect to sensor performance as measured by http://www.DxOMark.com. Canon doesn't even come close to the top performing Nikons.  (High score is better.):

Pts Model
=======
96 Nikon D800E
95 Nikon D800
94 Nikon D600
81 Canon 5D III
79 Canon 5D II

(The Canon 1Dx is not yet rated.)
What are the chances that one of the reasons for the new sensor in the 6D is to catapult Canon's sensor performance into the mid 90's? I can't see Canon doing that considering the $3,500 EOS 5D III just came out and has a score of just 81. But Nikon's new $2,100 D600 kicks butt with a score of 94!

Sensor performance isn't everything... but, if I were to choose Nikon or Canon today, I wouldn't be choosing Canon.

I have said this many times. You CAN NOT compare dynamic range on ISO100, and assume everybody works in ISO100, and that this is the correct ISO to measure by, like DxO does. I RARELY go below ISO 1600 for my kind of work.

BTW! Anyone find it strange DxO has the finished analysis/review of the D600 days after it is released? And they still haven't finished they analysis/review of the 1D-X !?

Well I don't find it strange at all, DxO is tight with Nikon, everybody should know that by now. I will not be surprised if they rate the 1D-X below the Nikon D3100, and neither should you! Do not expose your low intelligence by actually believing DxO is the standard for measuring camera low light and dynamic range performance.

The 5D3 has a MUCH better dynamic range, not to mention the low light ISO performance, than the D800 above ISO600.

Who cares what the Nikonioans down at DxO says, not me!

Have a nice day everyone!


mystic_theory

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #80 on: September 20, 2012, 04:06:42 AM »
It's amazing how much distance in DxO scores there is between Nikon sensors and the corresponding Canon ones: I agree that the overall score gives just a rough estimate of the overall quality of the sensor, but what worries me are the differences in high ISO noise and DR, which are instead very precise and reliable measurements.   :o
« Last Edit: September 20, 2012, 06:10:41 AM by mystic_theory »

sarangiman

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #81 on: September 20, 2012, 04:38:04 AM »
...
That said, DxO is a complete and total joke. This is a company that ranks consumer DSLRs above medium format digital backs in IQ.
...

There is no rule that says a MF digital back must be better at taking pictures than a DSLR.

If the design and technology used by the DSLR is superior to that of the digital back and delivers better images then it stands to reason that the sensor can be rated above a MF back.

+1

Thank you dilbert for stating what with common sense & logic should be apparent to everyone.

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #81 on: September 20, 2012, 04:38:04 AM »

sarangiman

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #82 on: September 20, 2012, 04:42:31 AM »
Quote
I have said this many times. You CAN NOT compare dynamic range on ISO100, and assume everybody works in ISO100, and that this is the correct ISO to measure by, like DxO does. I RARELY go below ISO 1600 for my kind of work.

You do realize that at base ISO, the D800 has more than 2.5EV more DR than the 5DIII, and at worse, i.e. at ISO 25,600, it has 0.26EV worse DR than the 5DIII. So, compare at whatever ISO you'd like. The D800 is rarely going to do worse than the 5DIII, but can do much better.

Furthermore, the future is likely 'ISO-less'. In other words, ISO becomes metadata written into the file, much like white balance. Amplification is done during RAW processing. That way, you actually retain the DR of base ISO even at high ISO (w/ low enough read noises).

We just need manufacturers (both hardware & software) to implement this. Personally, I would've already implemented this w/ the D800, given the low read noise of ~3 e-.

But maybe the industry is waiting for a read noise of 1 e-, or a 16-bit ADC.
« Last Edit: September 20, 2012, 03:40:13 PM by sarangiman »

Fishnose

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #83 on: September 20, 2012, 05:57:25 AM »
...
That said, DxO is a complete and total joke. This is a company that ranks consumer DSLRs above medium format digital backs in IQ.
...

There is no rule that says a MF digital back must be better at taking pictures than a DSLR.

If the design and technology used by the DSLR is superior to that of the digital back and delivers better images then it stands to reason that the sensor can be rated above a MF back.

+2

jthomson

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #84 on: September 20, 2012, 06:32:06 AM »

BTW! Anyone find it strange DxO has the finished analysis/review of the D600 days after it is released? And they still haven't finished they analysis/review of the 1D-X !?
...

Nope.

Nikon had the D600 on sale via the web/stores 5 days after it was announced, so it is likely that Nikon were able to ship a production matched D600 to DxO ahead of time.

How long did it take Canon to even get 1DX cameras out to folks that were going to need them for the Olympics? And how long did it take for the 1DX to show up in stores? Don't blame DxO for Canon's inability to delivery/perform.
[/quote]

DXO appears to have a Nikon bias.  They haven't released scores for the 1DX, the T4i or the Olympus OMD EM-5, but they get the D600 out within days of its release. 

Fishnose

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #85 on: September 20, 2012, 07:40:18 AM »
The rub here is that if you're Canon and you already know that your camera's sensor isn't going to score better than anything Nikon has published then you're not going to be in any sort of rush to have it tested by DxO. I don't know if DxO purchases the cameras for themselves or waits for vendors to send them freebies...

DxO being a rather small company, I would guess they are in the position of getting access to test subjects in a few ways:
1. Manufacturer or distributor sends them a copy to test (much like magazine/web reviewers are sent copies)
2. The company buys one, as the item in question is central to their lens testing
3. Someone on the staff buys one
4. They borrow one from someone else

If none of the above fits, they don't test it.

HarryWintergreen

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #86 on: September 20, 2012, 07:49:44 AM »
Sensor performance isn't everything...

Not only not everything, but far less than even remotely close to everything.  Consider all the glass the light must pass through before it even reaches the sensor.

Also consider that DxOMark is evaluating only the sensor, and also that their "Overall Score" is composite of three arbitrarily chosen "Use Case Scores" that are combined in a 'weighted' manner, but the weighting is not disclosed.  Furthermore, their use case scores are normalized to an 8 MP file size, which explains how a camera with 14 bits per pixel can, according to DxOMark, actually deliver a dynamic range greater than 14 bits of EV. 

IMO, their Measurements (screen) are valid and quite useful.  Their Scores are steaming pile of misleading cow excrement.

Just a little reality check...   :)

+1 (a bit late, I know). I wished any limitations referring to my photographic skills could be ascribed to dynamic range and what have you.  ;D

neuroanatomist

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #87 on: September 20, 2012, 09:05:04 AM »
...
That said, DxO is a complete and total joke. This is a company that ranks consumer DSLRs above medium format digital backs in IQ.
...
There is no rule that says a MF digital back must be better at taking pictures than a DSLR.

When did DxO start evaluating the ability of a camera to take pictures?  That statement implies lots of performance characteristics that DxO doesn't measure.  Their measurements are for specific aspects of sensor performance, as they define them (obviously, I'm referring to their sensor measurements, not their lens measurements).

DxO is also capable of telling you how lenses perform on various cameras, e.g. the 70-300L:
http://www.dxomark.com/index.php/Lenses/Camera-Lens-Database/Canon/EF70-300mm-f-4-5.6L-IS-USM/(camera)/436


Define capable, and in your definition please address their evaluation of the performance of the 70-200mm f/2.8L IS II, which they score lower than the MkI version of that lens.   :o
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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #87 on: September 20, 2012, 09:05:04 AM »

Viggo

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #88 on: September 20, 2012, 09:30:48 AM »

Define capable, and in your definition please address their evaluation of the performance of the 70-200mm f/2.8L IS II, which they score lower than the MkI version of that lens.   :o

Noooo? Are you kidding? Really, lower for the mk2? LOOOOL . That adds to the credibillity.... ::)
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itsnotmeyouknow

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #89 on: September 20, 2012, 09:36:53 AM »
http://gearburn.com/2012/08/canon-eos-1dx-review/

DxOMark doesn't mean anything...

Canon still better, specially in HI ISO...

I have the D800 and the 5D3, and I would agree that the Canon does better at high ISO.  For a predominantly landscpe shooter like myself, though the amount of banding at lower ISO in combination with not great DR renders the camera a handicap to me.  I have some great lenses that are very sharp but they have one hand tied behind their back by the banding issue.  I can push the shadows on a D800 shot and keep noise completely at bay and you have to push it way too far to get the chroma noise you get from the 5D3....I'm not a pixel peeper and I hate arbitrary resolution charts.  I judge on the image as a whole.  In some instances the banding on 5D3 is visible at 1024 px.  Not Good Enough for a camera that cost me £3200.  I can't live with that and whereas I had no alternative before, I do now.  This is what will cost Canon money.  I have 10 L lenses.  Yet I still feel the need to move to the Nikon d800.  Whether it is a permanent move depends on what Canon does next.  I am going to be selling the glass where I have overlaps and 3 of these will be L lenses.  I'll use the proceeds to get good zooms on Nikon. 
« Last Edit: September 20, 2012, 09:40:13 AM by itsnotmeyouknow »

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Re: DxOMark Sensor Performance: Nikon vs. Canon
« Reply #89 on: September 20, 2012, 09:36:53 AM »