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Old Sep 26, 2006, 9:09 AM   #21
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" I welcome any rebuttal based on technical grounds and with reference to applicable industrial standards and/or relevant documents. But so far there have been only very few. The usual "small sampling size" or "I have no problem at the field" arguments seem too weak to substantiate as a useful rebuttal."

Now let me get this straight, the argument that the camera works in the field just fine is a weak rebuttal to your finding minor faults with the camera in your lab (home) tests.

It seems to me if the camera works in the field, that is actually all that counts, since that is what most off us purchased them for, not as a test camera in a lab situation.

Technically a bumble bee isn't suppose to be able to fly, but there they go flying all over the place, never knowing they are breaking the rules of aerodynamics.

Tom
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Old Sep 26, 2006, 9:45 AM   #22
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That's exactly what has been bugging me about all of these tests. It gets to a point where you are splitting hairs. If one camera does something a milisecond faster than another, or weighs half an ounce less, or has 2 more megapixels...whatever! If the only way to actually be able to tell the difference is by doing a test in a lab and measuring the results with meters, who cares? If you can't see the difference with your eye, or feel the difference with your hand, why worry about it? If there are two 5 gallon buckets in front of you and both are full of water, does it matter if one has 3 more drops in it? Buy the camera you like!


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Old Sep 26, 2006, 10:20 AM   #23
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If you make part or all of your living with a camera, the test reports are interesting, but the real-world performance of the camera is the only thing that counts. If you can shoot sharp photographs at 1/8 second using the SR feature, who cares what some silly "test" shows? We don't get paid for testing cameras, we get paid for making images.

I plan to get the K10D when it is available, partly for the anti-shake feature. It's useful in real life.
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Old Sep 26, 2006, 10:32 AM   #24
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danag42 wrote:
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We don't get paid for testing cameras, we get paid for making images.
Actually, I pay quite a lot to be able to make images. And I'm still happy with my Pentax gear!

Kjell
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Old Sep 28, 2006, 9:05 AM   #25
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ennacac wrote:
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" I welcome any rebuttal based on technical grounds and with reference to applicable industrial standards and/or relevant documents. But so far there have been only very few. The usual "small sampling size" or "I have no problem at the field" arguments seem too weak to substantiate as a useful rebuttal."

Now let me get this straight, the argument that the camera works in the field just fine is a weak rebuttal to your finding minor faults with the camera in your lab (home) tests.

It seems to me if the camera works in the field, that is actually all that counts, since that is what most off us purchased them for, not as a test camera in a lab situation.

Technically a bumble bee isn't suppose to be able to fly, but there they go flying all over the place, never knowing they are breaking the rules of aerodynamics.

Tom
The problem is I found something were wrong in the *field*, say, the metering accuracy and the AF. Then, I verified this with calibration instructment, according to procedures designed based on some reference standards.

Some people say that they found no problem in the field, that's fine for me, as different people have different requirements or simply preference. But this doesn't mean our cameras are accurate if checked against certain industrial standards.

Also, the problem of my *ist D and DS is simply that inconsistency was found within the body itself, i.e. with different metering mode or with different lenses mounted.

My K100D suffers from the same problem with the Spot metering but now that the CW metering is okay. I found no problem in the field and then I verfied with my lab test and found no difference. Actually, my lab test results closely matched my practical experience, for most of the time!

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Old Sep 28, 2006, 9:10 AM   #26
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oreo57 wrote:
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Well said Mr. High....

as to tests and standards.. you maybe need to read this...

http://www.qualiteitems.com/Scene_Reflectance.pdf

Or this:

http://doug.kerr.home.att.net/pumpkin/#Optics
"EXPOSURE METER CALIBRATION" 70th Birthday

Make notes regarding the Canon section

"


[align=left]In any case, assuming that Canon's target value of Hu/Hsat is in fact[/align]

[align=left]0.173, we note that this is 0.43 stop "hotter" than the value implied[/align]

[align=left]by the ISO standards, 0.128............................................. .......[/align]

[align=left]As discussed in the body of the article, the adoption of this "above[/align]


[align=left]So that leaves Canon with only the possibility of achieving their target[/align]

[align=left]value of Hu/Hsat by using a non-standard rating of ISO sensitivity—a[/align]

[align=left]rating that is about 0.74 that which would be determined under ISO[/align]

[align=left]12232. In other words, the sensitivity that is designated "ISO 100" by[/align]

[align=left]Canon would probably be rated at about ISO 135 under ISO 12232."[/align]

[align=left]Please no rebuttal. We've been down this road once too often.... All I ask is you read the articles in the links I posted, no more no less.........[/align]

Thanks for the links. What the article points out is simply about the higher sensitivity of Canon DSLRs than it is specified. It is nothing to do with metering accuracy as the exposure can be adjusted with Canon's own sensitivity to make a proper match.

Of course, such deviation from the ISO standard for the marked/stated ISO speed is not so desirable just becoz it is a deviation. From my own tests carried out, I found Pentax DSLRs have never had such problem and the ISO speed is very accurate.

So, all in all, the ISO accuarcy has nothing to do with the metering and exposure accuarcy, again.

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Old Sep 28, 2006, 11:45 AM   #27
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Cameras are like any other tool which have positive and negative issues that need to worked with and around. My DS shows none of the issues you find in your tests, although I spend no time photographing flat panels to measure DOF to the mm, but I do require critical focus when using f/1.4-f/2.8. My DS focus's exactly where I want it, using MF and the images I end up with are always in focus, except for times where camera movement is a issue.

When my DS focuses exactly where I want it (and where is shows in the viewfinder) using my A* 85 (and all my other * lenses) wide open, so that is all the proof I need that my DS focus is working properly. Even my macro photographs are in focus using a macro lens and using a bellows, so it works for me.

Now I expect that if I tested it with a flat piece of paper down to the mm, it might be a mm or two off, but in practical application, that is of little value unless I decide to become a spy and photograph documents, instead of the subjects I photograph now.

Tom
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Old Sep 28, 2006, 1:36 PM   #28
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But this does..........

quote..................




[align=left]ABOUT "MID-SCALE GRAY"[/align]




[align=left]It is often said that the objective of the usual calibration of a reflected[/align]



[align=left]light exposure meter is that an object whose reflectance is the average[/align]



[align=left]reflectance of the scene will be given an exposure result that is[/align]



[align=left]considered "mid-scale gray", and that an exposure result that[/align]



[align=left]represents a luminance of about 18% of the luminance represented by[/align]



[align=left]the largest possible exposure result (that would be about[/align]



[align=left]RGB 118,118,118 in an sRGB color space) would be considered such[/align]



[align=left]a mid-scale gray.


[align=left]I won't attempt to comment on the idea that 18% relative luminance[/align]


[align=left]should be thought of as mid-scale gray.[/align]


[align=left]Note, however, that as we see above, for a camera automatic[/align]


[align=left]exposure system calibrated in accordance with ISO 2721, or for a[/align]


[align=left]shot taken under the guidance of an exposure meter calibrated under[/align]


[align=left]ISO 2720 with a
K of 12.7, an object whose reflectance is the same[/align]


[align=left]as the average reflectance of the scene will be given an 12.7%[/align]


[align=left]relative luminance result, not an 18% result.[/align]
[/align]



[align=left].......unquote[/align]



[align=left]No mention of 127 I see. A calibrated camera should have a peak LEFT of center w/ a grey card or white wall. Better look at your exposure data again. Apparently the k100 is overexposing [/align]



[align=left]http://www.qualiteitems.com/images/S...eflectance.pdf[/align]
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Old Sep 28, 2006, 1:45 PM   #29
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WE DON'T CARE.
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Old Sep 28, 2006, 2:12 PM   #30
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dequardo wrote:
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WE DON'T CARE.
Then stop reading/replying.

I am finding it amusing and informative in equal parts!



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