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11-27-2013, 08:30 AM   #31
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The distinction between an average score of 80 and an average score of 83 (based on the presence or absence of ISO 80) is too trivial to matter. My $1,300 spends the same as everyone else's.

The problem is, I'll take the time to think about that while almost everyone else will buy the "winner" and think they got someting better for their money.

11-27-2013, 09:33 AM - 1 Like   #32
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QuoteOriginally posted by Bolt Quote
I claimed that the results that the D800 had a Dynamic Range of 14.4 Evs compared to the 1D X's 11.8 is in part true, but an inaccurate representation of the tests overall results. Here is why:
D800

....
A Summary:

You've got a bunch of data points. If you try to summarize this bunch of data into a single value, you lose information that may or may not be important to the reader. However you try to summarize this bunch of data someone will complain about how you did it, even if you explain how you chose to summarize it. In particular, expect complaints when your method of summarizing doesn't support the conclusion that a particular person would like to see, especially when they can find a different method of summarizing that does (which is quite often possible if you try hard enough).

How to avoid this problem:

If you want the full, unbiased data to make a more informed decision, look at the full, unbiased data.
11-27-2013, 09:36 AM   #33
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I've no reason to doubt the integrity or objectivity of these folks, and I'll give them the benefit of the doubt regarding technical competence, but I can't interpret the quality of their results without understanding the following:

1) Number of samples tested; if DXO's data are generated from just a single camera body, then the results are only anecdotal observations - not necessarily useless but not something you can take to the bank, either.

2) A quantitative description of the experimental error in these measurements - maybe there's one on their website, but I haven't come across it.

3) A clearer picture of the relationship between differences in these measured results and differences in real-world performance. This sort of thing is admittedly difficult when the ultimate verdict on "Image Quality" contains personal and subjective elements - rather like the "Sound Quality" of musical instruments or "Great Handling" in sports cars.

I suppose that in the end the only meaningful tests of Image Quality are the ones you perform yourself; if you can't believe your own eyes . . . . .

Jer

Last edited by Sailor; 11-27-2013 at 09:47 AM.
11-27-2013, 09:44 AM   #34
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How many people here have a monitor capable of displaying 14EV?
The typical professional inkjet print is probably less than 9EV. It use to be 7EV.
What is the color depth of your monitor?

There are not a lot of advantages to buying a camera with 14EV and 23 bits of color depth to shoot 8-bit JPEGs or to display on an 8-bit monitor.

11-27-2013, 09:57 AM - 1 Like   #35
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QuoteOriginally posted by BrianR Quote
A Summary:

You've got a bunch of data points. If you try to summarize this bunch of data into a single value, you lose information that may or may not be important to the reader. However you try to summarize this bunch of data someone will complain about how you did it, even if you explain how you chose to summarize it. In particular, expect complaints when your method of summarizing doesn't support the conclusion that a particular person would like to see, especially when they can find a different method of summarizing that does (which is quite often possible if you try hard enough).

How to avoid this problem:

If you want the full, unbiased data to make a more informed decision, look at the full, unbiased data.
I guess you haven't seen the Lensrentals page where they scientifically tested sample variations on at least 10 lenses and plotted the results. Without standard deviations printed for each test, their results are pretty much meaningless. In fact any statistical analysis that doesn't include the standard deviation is meaningless. They haven't even established what the ranges are for each sample of the lens you intend to buy. They tell you what one lens they tested is like as far as I can tell. That doesn't tell you what the worst sample you might get or the best sample you might get would test. It tells you what one test was like, and therefore can't tell you what you're experience might be.

But is a lens is well rated on every platform, Pentax, Canon, NIkon, Nikon APS-c, Canon APS-c, like say the Sigma 35 1.4, then you know they;ve tested at least 3 lenses, making their tests a little more reliable. But in most cases you only find 3rd party lenses on non-Pentax cameras, and if you look at the ratings, lenses are rated lower on Pentax systems than on other systems.

There is no way these ratings can be considered in any way accurate, beyond the fact that on one camera, probably not a Pentax, one lens tested better than another lens. If everyone took DxOs advice, everyone would own Nikon D-800s. The best lenses have the highest scores on D-800s. The Pentax 645D is rated down with a K-5. These findings do not conform to the experiences of forum members. I personally cannot take DxO over the words and examples of forum members. Their measurements are too imprecise and based on the flawed notion, that the copy of the lens they have represents an average of the lens of the type being tested.

With no published standard deviation, no sample size listed, no range based on best and worst copies of the lens, no explanations for the different ratings on different sensors, no attempt to rationalize why the scores are so different on different bodies etc, their work is interesting but ultimately meaningless. I would ask people on the forum about a lens based on their numbers, but wouldn't go any further than that. I certainly wouldn't buy a lens or camera body, solely on what they publish.

They simply do not publish enough information for you to make an informed decision.
11-27-2013, 10:10 AM   #36
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QuoteOriginally posted by Winder Quote
How many people here have a monitor capable of displaying 14EV?
The typical professional inkjet print is probably less than 9EV. It use to be 7EV.
What is the color depth of your monitor?

There are not a lot of advantages to buying a camera with 14EV and 23 bits of color depth to shoot 8-bit JPEGs or to display on an 8-bit monitor.
The thing there is, you have control of contrast in PP, so you can take your 14 EV capture and compress it to 7 EV so all that data is visible in your print, by reducing the contrast. Very easy to do in post. Or you can compress it so all the data is displayed on your monitor. So even though you're viewing at the same reduced EV in both cases, capturing 13 EV is a huge advantage, as any of us who went from a K20D (11 something EV?) to a K-5 (13 something EV?) saw a huge difference. Details were visible in K-5 prints that wasn't even visible in the K20D image as captured. Photography has always been in part about how to compress a 20,000/1 contrast scene into a 100/1 print. For magazines it's as low as 60/1. More EV to start with means more detail in the finished print.
11-27-2013, 11:09 AM   #37
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QuoteOriginally posted by Winder Quote
There are not a lot of advantages to buying a camera with 14EV and 23 bits of color depth to shoot 8-bit JPEGs or to display on an 8-bit monitor.
QuoteOriginally posted by normhead Quote
The thing there is, you have control of contrast in PP, so you can take your 14 EV capture and compress it to 7 EV so all that data is visible in your print, by reducing the contrast. Very easy to do in post.
I'm talking about 8-bit JPEG (which the majority of people use) where you don't have any of those advantages. You are talking about RAW & post processing.

Even in RAW and post you are still very limited by an 8-bit display.
11-27-2013, 11:14 AM   #38
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QuoteOriginally posted by Winder Quote
I'm talking about 8-bit JPEG (which the majority of people use) where you don't have any of those advantages. You are talking about RAW & post processing.

Even in RAW and post you are still very limited by an 8-bit display.
IN which case your RAW engine will do the compression for you, and you still end up with a more detailed picture using a sensor with more EV. It is always best to have more DR, no mater what your end result the extra detail is never discarded, even in jpg. It may not have the same colour depth in 8 bit, but it will still be displayed as close as possible to to what was captured.

11-27-2013, 11:31 AM - 1 Like   #39
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QuoteOriginally posted by normhead Quote
I guess you haven't seen the Lensrentals page where they scientifically tested sample variations on at least 10 lenses and plotted the results.
And I guess you just like jumping to conclusions based on nothing at all that I said? Seriously, I think you sometimes just set out to disagree with things that aren't even there. I made no claims at all about the validity or non-validity of DxO, or now Lensrentals (No idea why they just came up?? Just because they did a test with multiple copies of a lens??). I was just speaking to the pointlessness of trying to claim one way of summarizing a data set is somehow more valid than another. They're just different points of view, and it's often best to look at all the data available when making your conclusions, even if that conclusion is 'not enough data available for my purposes'.
11-27-2013, 11:40 AM   #40
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QuoteOriginally posted by BrianR Quote
And I guess you just like jumping to conclusions based on nothing at all that I said? Seriously, I think you sometimes just set out to disagree with things that aren't even there. I made no claims at all about the validity or non-validity of DxO, or now Lensrentals (No idea why they just came up?? Just because they did a test with multiple copies of a lens??). I was just speaking to the pointlessness of trying to claim one way of summarizing a data set is somehow more valid than another. They're just different points of view, and it's often best to look at all the data available when making your conclusions, even if that conclusion is 'not enough data available for my purposes'.
And I'm just saying DxO doesn't let you look at their data. They let you look at their conclusions. First you have to trust that they used adequate data. Then you have to trust that the conclusions they draw are reasonable. Then you have to trust that they've constructed their rating system in a meaningful way that accurately presents that data.

That's a lot of "trust me."
11-27-2013, 01:15 PM   #41
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QuoteOriginally posted by normhead Quote
And I'm just saying DxO doesn't let you look at their data. They let you look at their conclusions. First you have to trust that they used adequate data. Then you have to trust that the conclusions they draw are reasonable. Then you have to trust that they've constructed their rating system in a meaningful way that accurately presents that data.
Their rating system could be subjective, but I think they display enough data for our comparisons, at least for me. What more could you expect than a straight forward 14eV vs 13.4eV or 60dB vs 61dB at ISO 122?

What's more, they detailed how they measure the sensors. And here's an interesting point I just found after reading through their explanation:
At Noise & dynamic range - DxOMark it is stated that "We use filters having different light absorption levels ranging from 0% to 99.99% in order to test across a dynamic range of 4 density steps (= 13.3 f-stops)." Now why do some sensor reach 14eVs when the target scene has only 13.3 eV? Turns out if you look at the "screen" dynamic range data, no camera could go over 13.5 eVs at ISO100, not the K-5, the D610 or the D800. From this evidence "prints" exaggerate DR values.

Going back to K-3 v D7100, it seems the Nikon does beat the K-3 fair n square. DXO screen DR data ( Side by side - DxOMark) shows that K-3 just couldn't keep up with the D7100. Both, however pales in comparison to the K-5 series which actually reached 13.5eV at ISo80 and 13.3eV at ISO100, which means it is the best APS-C sensor ever tested. I hope Ricoh didn't drive the engineer who worked the pixie dust on the K-5 away, they need him.
11-27-2013, 02:07 PM   #42
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QuoteOriginally posted by wahid_satu Quote
Both, however pales in comparison to the K-5 series which actually reached 13.5eV at ISo80 and 13.3eV at ISO100, which means it is the best APS-C sensor ever tested. I hope Ricoh didn't drive the engineer who worked the pixie dust on the K-5 away, they need him.
The K-3 has a better sensor than the K-5. You can't just ignore resolution.

Pentax does not design or manufacture sensors. According to GordonBGood at DPR, it is likely that the Sony 16mp sensor allowed for the extension of ISO to 80, whereas the Sony 24mp sensor does not.

Last edited by audiobomber; 11-27-2013 at 02:56 PM.
11-27-2013, 03:21 PM   #43
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QuoteOriginally posted by wahid_satu Quote
Their rating system could be subjective, but I think they display enough data for our comparisons, at least for me. What more could you expect than a straight forward 14eV vs 13.4eV or 60dB vs 61dB at ISO 122?

What's more, they detailed how they measure the sensors. And here's an interesting point I just found after reading through their explanation:
At Noise & dynamic range - DxOMark it is stated that "We use filters having different light absorption levels ranging from 0% to 99.99% in order to test across a dynamic range of 4 density steps (= 13.3 f-stops)." Now why do some sensor reach 14eVs when the target scene has only 13.3 eV? Turns out if you look at the "screen" dynamic range data, no camera could go over 13.5 eVs at ISO100, not the K-5, the D610 or the D800. From this evidence "prints" exaggerate DR values.

Going back to K-3 v D7100, it seems the Nikon does beat the K-3 fair n square. DXO screen DR data ( Side by side - DxOMark) shows that K-3 just couldn't keep up with the D7100. Both, however pales in comparison to the K-5 series which actually reached 13.5eV at ISo80 and 13.3eV at ISO100, which means it is the best APS-C sensor ever tested. I hope Ricoh didn't drive the engineer who worked the pixie dust on the K-5 away, they need him.
Really, as in you can tell the difference looking at images? I found I could tell the difference between a K20D and a K-5, but they were rated about 15 points apart. When I was looking at a D3200 (24MP) and a K-5 I couldn't tell the difference. When I was looking at a K-5 a D7000 I couldn't tell the difference. You're saying the K-3 and D7100 are two points apart, and you can tell the difference? "Just couldn't keep up" sounds a little dramatic.
11-27-2013, 03:48 PM   #44
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QuoteOriginally posted by audiobomber Quote
Pentax does not design or manufacture sensors. According to GordonBGood at DPR, it is likely that the Sony 16mp sensor allowed for the extension of ISO to 80, whereas the Sony 24mp sensor does not.
Going by the "screen" data sets provided by DXO, even without the ISO80 K-5 would still win. I gave you the link in my earlier post.

QuoteOriginally posted by normhead Quote
Really, as in you can tell the difference looking at images?
You were talking about data, I just followed suit. I did say the DXO final rating maybe subjective so ignore it and just see the DR data they gave us in "screen", which shows there are differences between The K-3 and the others and how it is lost compared to the D7100 and K-5. I'm just trying to convey that we should not discount their data.

QuoteOriginally posted by normhead Quote
"Just couldn't keep up" sounds a little dramatic.
Agree. A bit of dramatization on my part. I should just say the K-3 consistently records less DR than the D7100 and K-5 in ISO100-ISO800.
11-27-2013, 04:06 PM   #45
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Personably, does it really matter what they say? Most of us are so heavily invested in Pentax glass it doesn't matter what the score is, we still want the K3
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