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09-16-2016, 10:48 AM   #61
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Gotta love Tony Northrup's enthusiasm in PetaPixel's story for this DXO Mark result... Pentax K-1 a 'Full-Frame Marvel,' Third Best ILC DxOMark Has Ever Tested

"Honestly baffled by DxOMark's results. We tested this SO carefully against the D810 and, in our side-by-side tests, we simply couldn't distinguish the pictures. The noise at any ISO looked exactly the same... we even did blind tests with multiple nit-picky photographers. DXOMark shows that the K1 is about 15% cleaner than the D810, which I think we would have been able to see.

I'm also confused because we determined that ISO 100 on the K1 was actually about ISO 50 (about the same as ISO 64 on the D810)... but their ISO sensitivity scores show that the K1 is true to ISO... making it literally the first digital camera to stay true to ISO rankings.

Not the first time that DxOMark's scores completely diverge from our own test results... notably the a7S and 1DX II never looked as clean to us as it did to them."

09-16-2016, 11:01 AM   #62
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I have often wondered if DxO fudge part of their data, or took shortcuts... it's one of those mysteries of the universe.

QuoteQuote:
Not the first time that DxOMark's scores completely diverge from our own test results... notably the a7S and 1DX II never looked as clean to us as it did to them."
You have to remember, they shoot in a windowless space with nothing but one incandescent light. Which they claim is some kind of typical photography set up.

My understanding is the reason their values are so crooked is their lack of blue spectrum light in their test environment.

Under blue light, an APS-c sensor can be pushed theoretically to almost 100 MP. Under red light it will struggle to achieve 10 Mp. Here in lies my perceived problem with DxO. By limiting their light sources to red-yellow spectrum, they create an un-natural environment that will create much less resolution than out door shooting conditions. If DxO says your lens is good to 6 MP, I guarantee you it will be on a K-3 good to at least 18 Mp if the light source is blue spectrum. DxO, like any source is only useful if you are understanding exactly what they are talking about. If you're shooting a red flower under normal household lighting, then their evaluation may be dead on. If you're using any full spectrum light source, like oh, the sun, or any white balanced LED or Florescent source, it's all nonsense.

Just my take.

Last edited by normhead; 09-16-2016 at 11:39 AM.
09-16-2016, 01:14 PM   #63
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QuoteOriginally posted by ruggiex Quote
Gotta love Tony Northrup's enthusiasm in PetaPixel's story for this DXO Mark result... Pentax K-1 a 'Full-Frame Marvel,' Third Best ILC DxOMark Has Ever Tested

"Honestly baffled by DxOMark's results. We tested this SO carefully against the D810 and, in our side-by-side tests, we simply couldn't distinguish the pictures. The noise at any ISO looked exactly the same... we even did blind tests with multiple nit-picky photographers. DXOMark shows that the K1 is about 15% cleaner than the D810, which I think we would have been able to see.

I'm also confused because we determined that ISO 100 on the K1 was actually about ISO 50 (about the same as ISO 64 on the D810)... but their ISO sensitivity scores show that the K1 is true to ISO... making it literally the first digital camera to stay true to ISO rankings.

Not the first time that DxOMark's scores completely diverge from our own test results... notably the a7S and 1DX II never looked as clean to us as it did to them."
"making it literally the first digital camera to stay true to ISO rankings."

He obviously hasen't checked out Pentax before, just look at the K-3, spot on at the iso levels as well. Generally Pentax has always been closer to the real numbers then the competition.
09-16-2016, 04:41 PM   #64
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QuoteOriginally posted by ruggiex Quote
I'm also confused because we determined that ISO 100 on the K1 was actually about ISO 50 (about the same as ISO 64 on the D810)... but their ISO sensitivity scores show that the K1 is true to ISO... making it literally the first digital camera to stay true to ISO rankings.
People need to stop thinking about digital camera ISO as sensitivity, because its not. ISO for digital sensors is about applying digital gain to the signal to achieve the brightness indicated by the exposure index. Digital sensors don't have varying levels of sensitivity that you can change. Sensors have one set level of sensitivity (Base) and everything above that is achieved by amplifying they signal to maintain a brightness of 48.45%(sRGB).

ISO 12232:2006 The Recommended Exposure Index (REI) technique, new in the 2006 version of the standard, allows the manufacturer to specify a camera model’s EI choices arbitrarily . The choices are based solely on the manufacturer’s opinion of what EI values produce well-exposed sRGB images at the various sensor sensitivity settings. This is the only technique available under the standard for output formats that are not in the sRGB color space. This is also the only technique available under the standard when multi-zone metering (also called pattern metering) is used.

09-16-2016, 05:37 PM   #65
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Not so always. For example Sony a7r2 has two native ISO-values. One of ISO100 and another stage at ISO640 where it has better dynamic range than ISO400.

A7s has three points where it is better to use certain ISO values above something else. ISO3200 on that body gives better IQ than at ISO1600.

Leica Monochrom is 3rd case. Dun remember exact points but its DR is like sawtooth waveform across the ISO range.
09-16-2016, 06:06 PM   #66
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QuoteOriginally posted by MJKoski Quote
Not so always. For example Sony a7r2 has two native ISO-values. One of ISO100 and another stage at ISO640 where it has better dynamic range than ISO400.

A7s has three points where it is better to use certain ISO values above something else. ISO3200 on that body gives better IQ than at ISO1600.

Leica Monochrom is 3rd case. Dun remember exact points but its DR is like sawtooth waveform across the ISO range.
All of that is done through the image processor. Sensors don't have different ISO's. ISO is about applying digital gain not adjusting sensitivity. Some gain may be applied prior to the A/D converter and some applied after the A/D conversion. Where manufacturers chose to apply it and how much they apply can cause some stair step or saw tooth graphs.

Last edited by Winder; 09-16-2016 at 08:16 PM.
09-17-2016, 12:59 AM   #67
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In those cases at least Sony applies different analog gain scheme before the image processor. ISO640 is almost as good in real world as base ISO of 100.

This tech was licensed to R2.

I wished that the 42MP chip would be in K-1 but that did not happen. It really shines at high ISO.
09-17-2016, 01:40 AM   #68
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In real world the Sony 42 MPx chip is a failed piece of junk.

It's maximum dynamic range falls short of the many years old APSC K-5II, where it should be leading for at least 1,5 stops if it were to be competitive.
Compared to the APSC D7200 sensor the dynamic range at base ISO is just pathetic (-0,7 stops behind, where it should be leading with +1,5 stops plus some 0,3 to be expected for technological advances). With the Sony 42 MPx > -2,2 stops underperforming expectations that is worse than FF versus mFT.

09-17-2016, 02:27 AM   #69
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QuoteOriginally posted by Winder Quote
People need to stop thinking about digital camera ISO as sensitivity, because its not. ISO for digital sensors is about applying digital gain to the signal to achieve the brightness indicated by the exposure index. Digital sensors don't have varying levels of sensitivity that you can change. Sensors have one set level of sensitivity (Base) and everything above that is achieved by amplifying they signal to maintain a brightness of 48.45%(sRGB).

ISO 12232:2006 The Recommended Exposure Index (REI) technique, new in the 2006 version of the standard, allows the manufacturer to specify a camera model’s EI choices arbitrarily . The choices are based solely on the manufacturer’s opinion of what EI values produce well-exposed sRGB images at the various sensor sensitivity settings. This is the only technique available under the standard for output formats that are not in the sRGB color space. This is also the only technique available under the standard when multi-zone metering (also called pattern metering) is used.
I think of ISO purely with regard to the exposure triangle. So I want the same iso to give me the same shutter speed at the same aperture on whatever camera I shoot. My impression is that DXO Mark finds that some cameras need a longer shutter speed for the same ISO value than others. There is no particular reason why camera brands would do this, except that it makes their dynamic range and noise look more impressive than if they put the true value in.
09-17-2016, 03:21 AM   #70
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QuoteOriginally posted by Gimbal Quote
He obviously hasen't checked out Pentax before, just look at the K-3, spot on at the iso levels as well. Generally Pentax has always been closer to the real numbers then the competition.
yes, despite canikon have started cheating more and more with programmed vs actual iso, Pentax have not followed the trend.

---------- Post added 17-09-16 at 12:29 ----------

QuoteOriginally posted by Winder Quote
People need to stop thinking about digital camera ISO as sensitivity, because its not. ISO for digital sensors is about applying digital gain to the signal to achieve the brightness indicated by the exposure index.
While that is true, you know that shutter speed depends on ISO. For example , I you put two cameras side by side, ev compensation and ISO in 1/3rd EV steps, a Pentax, and a Nikon D7200, the shutter speed of the D7200 will be slower. The D7200 is doing ETTR and downscale brightness by processing the raw... that's precisely why you get both better SNR figures on 18% gray card and also the shifted ISO curve on the DXO chart. IMO, even if digital expose can be arbitrary, the relationship of iso with shutter speed is still the same. If I understood correctly, Nikon gets the top ranking of DXO but Nikon users are all cheated because in real situation, ISO has to be increase on the NIKON to have the same shutter speed as on a Pentax gear?
09-17-2016, 04:17 AM   #71
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QuoteOriginally posted by beholder3 Quote
In real world the Sony 42 MPx chip is a failed piece of junk.

It's maximum dynamic range falls short of the many years old APSC K-5II, where it should be leading for at least 1,5 stops if it were to be competitive.
Compared to the APSC D7200 sensor the dynamic range at base ISO is just pathetic (-0,7 stops behind, where it should be leading with +1,5 stops plus some 0,3 to be expected for technological advances). With the Sony 42 MPx > -2,2 stops underperforming expectations that is worse than FF versus mFT.
What are you smoking? In Sony's R2 it is held back only by artificial 30 second limitation where 14bit mode drops to 12bit. DxOmark readings have very little to do with real world.

Check this: Photographic Dynamic Range versus ISO Setting

K-1 vs. A7R2.
09-17-2016, 04:28 AM   #72
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When you look at the DXO top 10 you get this list:

1. A7RII 98
2. D810 97
3. RX1R II 97
4. K-1 96
5. D800E 96
6. A7R 95
7. D800 95
8. D600 94
9. D610 94
10. D750 93

But when you look at the ranking in each category and add them up you get another list (lowest points win)

1. K-1 13 points
2. D810 23 points
3. A7R II 24 points
4. D800E 25 points
5. RX1R 29 Points
6. D800 30 points
7. D600 31 points
8. D610 33 points
9. D750 38 points
10. A7R 40 points

This gives another view of the K-1 where the weight is more evenly distributed over categories.
09-17-2016, 05:08 AM   #73
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The scores gives you only one set of data from a whole range of measurements and thus can be misleading. For instance compare the 810 and the K1 and look at the dynamic range graph. The 810 wins by a small margin at one point, the iso 64 setting, which the K1 doesn't have. But the K1 wins between iso100 - iso12800 (after that they are equal).

So in one setting the 810 wins, in all others the K1 wins. Which is the better one?
09-17-2016, 05:25 AM   #74
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The better one is the one which suits your needs? Differences are so small between K-1 and D810 in reality that lens selection and perhaps body features are the factors in play. Like tilt-screen -> pick K-1. Like Sigma ART series -> pick Nikon (or Canon).
09-17-2016, 06:47 AM   #75
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QuoteOriginally posted by Rondec Quote
I think of ISO purely with regard to the exposure triangle.
QuoteOriginally posted by biz-engineer Quote
While that is true, you know that shutter speed depends on ISO.
How we operate our cameras hasn't changed, but how the sensor is working is not the same as film. This is a thread about the sensor performance and people keep talking about ISO like there is actually varying levels of sensitivity, and that is not the case.

---------- Post added 09-17-16 at 09:01 AM ----------

QuoteOriginally posted by biz-engineer Quote
the relationship of iso with shutter speed is still the same.
Yes the relationship is still roughly the same or hand held light meters wouldn't work with DSLRs. Some manufacturers are exposing for 12% gray and some are exposing for 18% gray. It's not that they are cheating ISO, they are simply using a slightly different standard.
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