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Messages - dtaylor

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256
EOS Bodies - For Stills / Re: Canon EOS-1D X DXOMark Sensor Scores
« on: October 16, 2012, 09:48:26 AM »
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Try this: shoot 4x5 Velvia. Drum scan it. Down sample to 10 MP. Did you all of a sudden gain 3-4 stops of shadow detail? No? Hmmm...

Here's a different test for you -- sample it at 10MP, create another image at 40MP. Then compute the "blackpoint" (SNR = 0db) of the two images.

Now I take it that we agree that the images both have the same "true"  dynamic range, but I put it to you that the measured blackpoint on the 40MP will be at a higher luminance level, and therefore the measured per-pixel dynamic range will be lower on the 40MP image.

The second test is irrelevant because measuring the black point is not the same as measuring the floor of useful photographic detail. Assuming that it is leads to flawed extrapolations, such as DxO's 'normalized' DR graphs, or 9-stop scanned LF Velvia.

257
EOS Bodies - For Stills / Re: Canon EOS-1D X DXOMark Sensor Scores
« on: October 16, 2012, 09:27:10 AM »
You must have never used the sheer awesomeness of the canon 61-Point AF system And yes, I've used nikons excellent 51-point system as well. So yes, I can say the Canon AF system is better than nikons right now. Plus, I never said that point count makes a better AF system, because then S0&y would be the best then.  ::)

My apologies for assuming that your judgement was based merely on AF point count. I read that into your statement and it was not warranted.

258
EOS Bodies - For Stills / Re: Canon EOS-1D X DXOMark Sensor Scores
« on: October 15, 2012, 06:22:31 PM »
What should be remembered is that doubling the resolution adds:

    3dB to the normalized SNR
    0.5 bit to the normalized DR

So according to DxO if we drum scan 4x5 Velvia, a 6 stop film, and down sample to 8 MP, we will end up with 9 stops of usable photographic detail?  ::)

Go ahead and try it  ;D

259
EOS Bodies - For Stills / Re: Canon EOS-1D X DXOMark Sensor Scores
« on: October 15, 2012, 06:15:53 PM »
Canon 61 pt AF > Nikon 51 pt AF. done.

Nonsense. Point count != superior AF. In my experience the 7D's AF is superior to the D7000's, practically on par with the earlier 45 point 1D bodies and several Nikon 51 point bodies, and it only has 19 points.

I don't honestly know who has the best AF right now because I don't spend sufficient time with the top tier bodies. But AF is an extremely complicated thing to objectively test, and subjective opinions are open to bias and error. AF performance can also be better on body A for situation 1, but better on body B for situation 2, etc, etc. Not to mention that lenses are at least as important as anything in the body, and it's a mistake to assume similar lenses from two manufacturers have similar AF.

Even with a case as one sided on paper as the 6D and D600 you can't conclusively say one body is always better than another. There's little point in discussing the top tier bodies unless you happen to own and shoot both regularly under a range of challenging conditions.

260
EOS Bodies - For Stills / Re: Canon EOS-1D X DXOMark Sensor Scores
« on: October 15, 2012, 05:56:58 PM »
You keep repeating it, but it's still wrong. It's wrong because the low end of the dynamic range is determined by SNR, and SNR changes when you downsample.

This is the belief of a math geek who spends too much time with graphs and not enough time with real photographs. Down sampling throws away noise and detail. Dynamic range is the range of useful photographic detail. It is not the simple difference between two numbers on a graph.

Try this: shoot 4x5 Velvia. Drum scan it. Down sample to 10 MP. Did you all of a sudden gain 3-4 stops of shadow detail? No? Hmmm...

Side note: arguments like this are why I hate DR by software analysis. It has zero bearing on the real world. It just leads to paragraphs and paragraphs of irrelevant and pointless theorizing. Shoot a Stouffer transmission step wedge and look at it with your own two eyes. That tells you what you can expect in the real world.

261
Canon General / Re: DxOMark vs. Reality
« on: October 11, 2012, 03:49:55 AM »
If you still do not accept that it is possible to increase DR by down-sampling, I would take a look at the many applications in which oversampling is used to improve performance.

Over sampling and down sampling are two different things.

262
Canon General / Re: DxOMark vs. Reality
« on: October 11, 2012, 03:39:27 AM »
Ok, I take this as asking:

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Nonlinearity has not yet been incorporated into sensors. You can compress more than 8 stops into an 8-bit JPEG this way (i.e. Canon HTP), but RAWs are simply not non-linear at this time.

Get a clue man, you have no idea what you are talking about. Sensors and amplifiers are nonlinear, whatever you do.

I love how the excuse for DxO's results keeps changing. It's due to down scaling. No, it's due to non-linear sensors / amps. No, it's due to... You guys need to get together and compare your notes   ::)

The sensors are not designed to expand DR through non-linear behavior. They are, for the purposes of this discussion, linear. Further more, they have noise. And like all analog to digital systems their range is actually less than on paper because of things like noise.

If they were absolutely perfect in every way you could expect a maximum of 14 stops. They're not.

Face it: DxO botched another test.

Now if you'll excuse me, I have to order my Nikon D3200 through Amazon since it's better than a Hasselblad. Talk about a steal  ;D

263
Canon General / Re: DxOMark vs. Reality
« on: October 11, 2012, 03:30:21 AM »
Here we go again with the same discredited arguments ...

I, for one, can't take DxOMark seriously or trust any of their numbers when they...

* Rank $40,000 medium format digital backs lower than consumer APS-C DSLRs.

There's nothing necessarily "wrong" with this per se. A medium format back is not necessarily better as a general purpose camera than an APS-C camera.

You know darn well their scores do not reflect how good the camera is as a "general purpose camera."
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I doubt that anyone is seriously using the website to decide whether to choose an APS-C or a MF back, so this argument is a silly red herring (usually trotted out by camera "fans" of low scoring cameras)

It's not relevant whether or not people are looking to them, and this is not a red herring. Their scores are consistently presented by them and others as IQ scores, yet their methodology is obviously flawed if they can give a consumer APS-C sensor a higher IQ score than a MFDB. This obvious error is usually ignored by "fans" of high scoring cameras. When a "fan" wishes to compare, say, Canon and Nikon, then all of a sudden the score is a score of overall IQ that we all must concede. When the same "fan" is confronted with the fact that the score for a consumer DSLR is higher than a 40 MP MF back, all of a sudden the score isn't a score of overall IQ, and nobody is using those scores to begin with, and stop tossing out red herrings.

Which is it?

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This horse has been beaten to dust. They report 13.2 bits for each pixel. You can gain dynamic range by downsampling. 14.4 stops is based on downsampling to 8mpx.

You cannot gain dynamic range by down sampling because you throw away detail with noise. If you think you can, your definition of DR is flawed.

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* Report values for dynamic range that I know to be false from both personal experience and testing. (They rank the 10D, 20D, and 7D about the same. The 7D is a good 2 stops better.)

You keep saying that these are "about the same", and I keep calling you on it. They are not "about the same".

They show a 0.7 stop difference when it's roughly 2 stops.

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For all the critics of DxOMark critics, I would like to point out that no less a professional and respected figure than Michael Reichmann stopped using DxOMark because of the obvious errors he observed in their results.

What precisely are his criticisms ? What exactly are his credentials as far as engineering and benchmarking are concerned ?
[/quote]

Visit his website.

264
Canon General / Re: DxOMark vs. Reality
« on: October 10, 2012, 04:47:39 AM »
DxO, here we go again.

DxO defender, here we go again.

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If you think, that a sensor (and I said sensor, not camera) can be fully described with an overall score in 0-100, you are silly.

Ergo DxO is silly because that is exactly what they claim can be done when they publish their scores. I will stop hammering them for their stupid overall scores when they remove them all from the site.

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And they have the charts. This is the data. If you know, what to look for, DxO is a valuable source of information, which can not be compared to any other review, as this is standardized and reproducible.

I contest this point. At least as far as dynamic range is concerned, there are repeat instances where they are clearly wrong.

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But again: if you don't go for the charts, you waste your time. And ours as well, as we have to read all this "biased", "crap", "not reflecting reality" comments, which are based on the lack of knowledge.

Are you part of DxO? Well...we will stop "wasting your time" when you stop wasting ours publishing silly overall scores that are repeated ad nauseam in forums. And when you correct some of the obvious flaws in your test results.
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* Rank $40,000 medium format digital backs lower than consumer APS-C DSLRs.
Medium format backs are expensive...

Yes, they are. Their IQ also wipes the floor with consumer APS-C equipment. (And that's coming from a huge fan of today's APS-C sensors!) And DxO looks stupid for claiming otherwise.

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* Report physically unachievable values for dynamic range (i.e. >14 stops from a 14-bit ADC).
Nonlinearity? Yes, it ruins the uniform sensitivity, but it exists, whatever you do.

Nonlinearity has not yet been incorporated into sensors. You can compress more than 8 stops into an 8-bit JPEG this way (i.e. Canon HTP), but RAWs are simply not non-linear at this time.

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* Report values for dynamic range that I know to be false from both personal experience and testing. (They rank the 10D, 20D, and 7D about the same. The 7D is a good 2 stops better.)
The "about the same" is 0,7 EV difference, not to mention, that I would be interested in those tests.

If you work for DxO, do the entire team a favor: buy a transmission step wedge and use it. Don't run it through a flawed computer analysis. Actually use it and eyeball the output. You will be embarrassed at some of the mistakes in your database.

265
Canon General / Re: DxOMark vs. Reality
« on: October 09, 2012, 10:16:35 PM »
IIRC, the DxOMark website says (somewhere) that their sensor scores can only be used to compare sensors of the same resolution (MP). So, first decide the resolution of sensor you are interested in (need), then compare sensors of that resolution.

Post #1 doesn't seem to recognise this.

I would be curious to see that if you have a link. If true, they need to post this in big, bold type on every page.

266
EOS Bodies / Re: Who said Canon cameras suck?!?
« on: October 09, 2012, 06:07:42 PM »
Chill Dtaylor.... you can't bully people into agreeing with you...


Bullying? ::) I don't think I'm the one who needs to chill.

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everyone has their own sense of reality that governs their perceptions and opinions.


Silly me...I thought we lived in a common, measurable reality.

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I saw the noise... He saw the noise....


Allow me to quote jrista:
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That "uniform" nature? Thats called photon shot noise. It's a physical effect caused by the NATURAL random distribution of light that follows Poisson distribution (http://en.wikipedia.org/wiki/Poisson_noise#Poisson_noise_and_characterizing_small_occurrences). FYI...every single camera on earth experiences photon shot noise, regardless of who makes it or how good it may be.


There was no noise. There was nothing that could be interpreted as noise until 100% pixel peeping, at which point you see the natural random distribution of light. And even that is difficult to make out. If that bothers you...if you want plastic skies while pixel peeping at 100%...it is stupid simple to make the sky plastic in PS.

But I hope I'm not being a bully in pointing that out  8)

267
EOS Bodies - For Stills / Re: 650D Results on DxOMark
« on: October 09, 2012, 05:02:30 PM »
Try a twisty british b road.  Hairpins. Blind summits. Corvette Rwd.  That kind of power.   FWD Civic type R hands down.

Someone who knows how to drive the Corvette and manage its power...which isn't that hard with traction control on...will smoke the Civic. I don't care what the course is. The difference in skid pad rating is huge. The difference in braking is huge. The difference in the ability to accelerate out of corner braking is huge.

"I didn't know how much power I had and slammed the car into the mountain" is not the same as "the Civic can beat the Corvette."

But you've blown the analogy completely out of proportion. DxO is telling you the Civic has more HP and is faster on a straight course. Do you believe them?

268
EOS Bodies - For Stills / Re: 650D Results on DxOMark
« on: October 09, 2012, 03:52:47 PM »
@dtaylor
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You're telling me to trust a testing company that tests a Honda Civic and a Corvette ZR-1 and reports that the Civic is faster with more HP. Please...

I would take a honda civic over a corvette anyday.  In fact strike that.  I'd take the Corvette and sell it and buy two honda Civics.

Here in Europe we like cars that can go round corners.

If you think a Civic can out corner a ZR-1, you're on some really good drugs man  ;D

269
EOS Bodies / Re: Looks like the 6D may not be so bad after all
« on: October 09, 2012, 03:47:20 PM »
Thanks for your clear words. You are rigth, these are no scientific tests.
But as an normal user I want to get
"normal" pictures out of my camera. No professional images, but images, where I am satisfied.
And if - in sum - my personal Camera puts grainy pictures out (6 persons changed the cameras around and worked with the 7D of another person for 4 weeks, taking more then 1500 pics each) even when we change the user, and another Camera does produce much better images, then you CAN say, that this special camera suffers from more grain.

Then stop wasting time in an Internet forum and get it repaired.

270
Canon General / Re: DxOMark vs. Reality
« on: October 09, 2012, 03:43:37 PM »
I, for one, can't take DxOMark seriously or trust any of their numbers when they...

* Rank $40,000 medium format digital backs lower than consumer APS-C DSLRs.

* Report physically unachievable values for dynamic range (i.e. >14 stops from a 14-bit ADC).

* Report values for dynamic range that I know to be false from both personal experience and testing. (They rank the 10D, 20D, and 7D about the same. The 7D is a good 2 stops better.)

For all the critics of DxOMark critics, I would like to point out that no less a professional and respected figure than Michael Reichmann stopped using DxOMark because of the obvious errors he observed in their results.

All that said...I wish Canon would lower their prices  ;)

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