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02-15-2008, 09:40 AM   #46
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QuoteOriginally posted by JMS Quote
Let the true population distribution of the AF speed at a given light level with a given AF unit and voltage supplied have mean 1 and standard deviation 0.05.

Then, let the true population be estimated by a study with sample size n=100 tests.

The distribution of x-bar will have mean 1 and standard deviation of 0.005.
Mathematics, Great!

Looking at the curve ... it is not smooth enough for a 5% std.dev. in the first place.
And they didn't do 100 identical tests per setup, no way. Maybe 2 or 3.

So indeed, they did copy paste.

02-15-2008, 09:41 AM   #47
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QuoteOriginally posted by JMS Quote
I disagree. You need to work on your statistics.

Let the true population distribution of the AF speed at a given light level with a given AF unit and voltage supplied have mean 1 and standard deviation 0.05.

Then, let the true population be estimated by a study with sample size n=100 tests.

The distribution of x-bar will have mean 1 and standard deviation of 0.005. Thus the probability can be easily calculated that if PopPhoto's tests are accurate, there would be approximately a 95% chance that a second test will yield the same results as the first at each light level if exact to the .01 level. At 9 light levels total, there is approximately a 63% chance of identical results.
Hello JMS!

I definately have to work on my statistics and as well as on my English as both aren't my special subjects. So I'm not sure if I could follow you on the first part of your posting. Do you suggest that Popphoto repeated the focussing test on each light level n=100 times and then averaged the numbers? If true I will agree that with equal hardware and equal circumstances such identical results might be possible. However I assumed a single testing on each light level.

I've just revisited the results and found an indication that makes my point quite clear: Whereas the focusing speed gets slower for every lower light level, the number for EV8 is in fact lower than the number for EV10. So here the K10D focuses faster, if the ambient light falls by 2 stops?! This is perfectly possible with a single measurement and nothing to worry about. But of course this error should disapear with higher n. And how about the chance that this anomaly recurs at the same step (EV10 --> EV8) with the K20D on a controlled test 13 months after the first one?

The main point of my first post was the practical improbability of the results, assuming one testing on each light level. N must be very high to get equal results with an equal setting. And this setting is obviously not equal. I hope you can agree on this.

P.S.: I'm sorry for any misunderstanding as a result of my modest English and my rather intuitive approach to statistics.

Have a nice day!
02-16-2008, 01:46 PM   #48
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No problem- your English is actually pretty good. I was just attempting to point out that since we don't have any of the data that PopPhoto used, we can't really speculate on whether or not they just copied and pasted. If n=100, they probably didn't. If n=1, they probably did.
02-16-2008, 03:59 PM   #49
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QuoteOriginally posted by jms698 Quote
someone in that other forum has posted the text of a Pop Photo review of the final version of the K20d

Pop Photo K20D review - March 2008: Pentax SLR Talk Forum: Digital Photography Review

The review is up on PopPhoto.com -

Camera Test: Pentax K20D - - PopPhotoMarch 2008

02-16-2008, 06:34 PM   #50
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I don't get it. Ok, so the nitpicking is there, but the cover blurb says "With rich features, a big 14.6MP sensor, and an estimated street price of $1,299, Pentax's super DSLR is a rare talent". What are we complaining about? I feel they were quite ok about it.
02-16-2008, 07:44 PM   #51
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QuoteOriginally posted by countzero Quote
I don't get it. Ok, so the nitpicking is there, but the cover blurb says "With rich features, a big 14.6MP sensor, and an estimated street price of $1,299, Pentax's super DSLR is a rare talent". What are we complaining about? I feel they were quite ok about it.
For those who still don't understand, my suggestion is to compare the test results against other DSLR tests. It's just as simple as that.

Btw, I have summarised the PopPhoto test results of the K20D, 40D, D300 and A700 in single tables for direct and easy comparison, just look and judge yourself:-

RiceHigh's Pentax Blog: First K20D Production Camera Formal Test
02-16-2008, 08:39 PM   #52
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The true test will be from off the street photographers who buy the camera! Word of mouth from other photographer will make this camera live or die not some reviewer in a photo mag. I show my photo's to other photograpers at flickr meets Cannon / Nikion user. They like what they see. Even better when I tell the price of my Pentax system! Deep down C & N users have a respect for pentax due to pentax's film days. In the days of online no manaufactuer can hide behide a false rewiew by a bias camera mag!
02-16-2008, 09:17 PM   #53
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QuoteOriginally posted by RiceHigh Quote
For those who still don't understand, my suggestion is to compare the test results against other DSLR tests. It's just as simple as that.

Btw, I have summarised the PopPhoto test results of the K20D, 40D, D300 and A700 in single tables for direct and easy comparison, just look and judge yourself:-

RiceHigh's Pentax Blog: First K20D Production Camera Formal Test

You forgot to tell, like pop photo , which setting was the noise reduction in the camera. In your "mighty" blog you didn't even comment about that issue, although you are familiar with the splotchy noise at 3200 and 6400 iso from the A700 and the 3 settings of noise reduction in the K20D. You also forget to mention the new af trap focus function speed or at least to make a question mark on why pop photo didn't measure with it.

You are as superficial as the pop photo reviewer, who in my opinion should test only point and shot cameras on "Auto" if they have no idea how to change a setting in their dslr.

Also why didn't you put this on your blog ?
https://www.pentaxforums.com/forums/173004-post13.html
Where K20D beats down every other aps dslr in detail and noise ? But we know why, you only hand pick information that say pentax is worse than the competition and you omit any other where it say is better.


Last edited by raz; 02-16-2008 at 10:29 PM.
02-16-2008, 10:00 PM   #54
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QuoteOriginally posted by raz Quote
Also why didn't you put this on your blog ?
https://www.pentaxforums.com/forums/173004-post13.html
Where K20D beats down every other aps dslr in detail and noise ? But we know why, you only hand pick information that say pentax is worse than the competition and you omit any other where it say is better.
Well I wouldn't say "wins hands down [to] every other dslr in detail and noise" , but 2nd to the D3 (@ ultra hi ISO) is plenty good for me! Regarding the next sentence, that's why so many members have used the "ignore user" (aka 'twit filter' for us old BBS users) feature of the site. If you/others wouldn't respond & quote 'em, we/I'd never see his neg-only/hater utterings again.
02-16-2008, 10:35 PM   #55
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m8o, yes that's why I said between "aps dslr", D3 is a full frame
02-16-2008, 10:44 PM   #56
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My Take: A Rave Review from Pop Photo

The DPReview is not at all like the Pop Photo review in my magazine, downloaded within the last few days. This is as close to a rave review as Pop Photo has ever done on a camera costing less that 2.5 grand.

WHAT'S HOT
  • 14.6 Megapixel sensor with live view
  • Tough body with extensive weather and dust seals
  • Excellent image quality up to ISO 1600

WHAT'S NOT
  • Burst mode only up to 3 fps for 38 JPEGs
  • Blackout time for AF in Live View mode
  • Accepts only SD and SDHC cards

WHO'S THIS FOR?
Photographers looking for a high-megapixel DSLR with a tough body, built-in image stabilization, and sophisticated controls at a good price
02-17-2008, 02:27 AM   #57
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I recently attended a seminar on RAW converters. They had the same photos from one camera processed through Capture One, Lightroom, etc etc. The difference was amazing.

So when reviewing digital cameras - usually on the web - what are we actually looking at? There are so many conclusions made by people looking at JPEGS. It means nothing.

The best way would be to scan some film at 14MP resolution, print it at 300 dpi. Then take a digital photo at same, equivalent, resolution AND PRINT IT. Then you've got an idea.

It's the prints guys. Make a print. Do a print. Then decide.

As for the review at Pop photo - it sounded pretty favourable to me. But what are they looking at? I'd want to see a print. But I don't believe any advertising or reviews. It's all hype. Every digital camera approaches the 'quality of film' - until the next year where it 'now approaches film'. Oh, right! Hmmm.
02-17-2008, 05:55 AM   #58
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QuoteOriginally posted by Adrian Owerko Quote
The true test will be from off the street photographers who buy the camera! Word of mouth from other photographer will make this camera live or die not some reviewer in a photo mag. I show my photo's to other photograpers at flickr meets Cannon / Nikion user. They like what they see. Even better when I tell the price of my Pentax system! Deep down C & N users have a respect for pentax due to pentax's film days. In the days of online no manaufactuer can hide behide a false rewiew by a bias camera mag!
These are not called tests, but just subjective opinions.
02-17-2008, 06:03 AM   #59
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QuoteOriginally posted by raz Quote
You are as superficial as the pop photo reviewer, who in my opinion should test only point and shot cameras on "Auto" if they have no idea how to change a setting in their dslr.
Why each time and every time it must be the Pentax's DSLRs which the testers (e.g. DPR, PopPhoto etc.) don't know how to use it and how to set the cameras??

The truth is those renowned testers are far more knowledgable than any average Joe in using any camera gear and know very well how to get the best out of a camera. Do you think any one of us actually knows better than those gurus?

QuoteQuote:
Also why didn't you put this on your blog ?
https://www.pentaxforums.com/forums/173004-post13.html
Where K20D beats down every other aps dslr in detail and noise ? But we know why, you only hand pick information that say pentax is worse than the competition and you omit any other where it say is better.
Those are test images with no data measured, nor, they were made by production unit of the K20D. Noise wise, I can still see plenty of noise in the shadow areas despite that the K20D pics have a bit more exposure level than the others, which are brighter. So, it's very normal that a brighter portion of the picture will have less noise, no surprise here. Last but not least, all the EXIF info are deleted in the original individual test pics, which makes them a bit suspective. So, I opted not to report and comment on those pics.
02-17-2008, 06:06 AM   #60
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Everyone knows about all those published specs and features. So what?

QuoteOriginally posted by Canada_Rockies Quote
The DPReview is not at all like the Pop Photo review in my magazine, downloaded within the last few days. This is as close to a rave review as Pop Photo has ever done on a camera costing less that 2.5 grand.

WHAT'S HOT
  • 14.6 Megapixel sensor with live view
  • Tough body with extensive weather and dust seals
  • Excellent image quality up to ISO 1600

WHAT'S NOT
  • Burst mode only up to 3 fps for 38 JPEGs
  • Blackout time for AF in Live View mode
  • Accepts only SD and SDHC cards

WHO'S THIS FOR?
Photographers looking for a high-megapixel DSLR with a tough body, built-in image stabilization, and sophisticated controls at a good price
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