pris sur un autre forum http://www.pentaxforums.com/forums/pentax-news-rumors/25521-magazine-review-k20d-sdm-af-c-performance-vs-8-competitors-good-info.html
(c) This is my own wrap-up and must not be copy-pasted to another forum/blog.
- Good/near scientific test with credible results
- Good choice of gear
(e.g.: K20D with DA* 50-135mm f/2.8 SDM lens -- first K20D/SDM AF test ever!)
- K20D came in last but still close enough to the rest of the pack, i.e., still good.
Source: fotoMAGAZIN (Germany) (fotoMagazin), Nr. 5/2008, p30ff.
40D: Canon 40D + EF 70-200 f/2.8 L IS USM (3230,- € German list price)
1D: Canon 1D-mkIII + EF 70-200 f/2.8 L IS USM (6390,- € German list price)
1Ds: Canon 1Ds-mkIII + EF 70-200 f/2.8 L IS USM (10290,- € German list price)
D80: Nikon D80 + Nikkor 70-200 f/2.8 VR G IF-ED (3260,- € German list price)
D300: Nikon D300 + Nikkor 70-200 f/2.8 VR G IF-ED (4120,- € German list price)
D3: Nikon D3 + Nikkor 70-200 f/2.8 VR G IF-ED (7140,- € German list price)
E3: Olympus E3 + Zuiko 50-200 f/2.8-3.5 ED SWD (3100,- € German list price)
K20: Pentax K20D + DA* 50-135mm f/2.8 ED IF SDM (2180,- € German list price)
A700: Sony Alpha 700 + 70-200 f/2.8 G SSM (3800,- € German list price)
(Order and prices as chosen by original print, K20 has best price in the field due to affordable DA* lens.)
Result (Test #4 -- Relative ratio of out-of-focus shots, central AF):
A700: 2.1 %
40D: 6.4 %
D3: 9.2 %
D300: 10.0 %
1D: 11.7 %
1Ds: 14.3 %
E3: 17.8 %
D80: 23.2 % (but 10.7 % with multi-field AF)
K20: 25.6 % (and 43.6 % with multi AF)
Result (Test #3 -- Absolute number of in-focus shots, central AF):
1D: 30.2 images
D3: 21.6 images
40D: 20.6 images
A700: 15.3 images
1Ds: 15.0 images
D300: 13.5 images
D80: 8.6 images (10.7 with multi AF)
E3: 7.4 images
K20: 5.8 images
3.7 images (with multi-field AF, other multi-field AF results ommitted here)
Continous shots (burst, continous AF aka AF.C) of an approaching red Chrysler PT cruiser, tripod mounted and panned centering onto radiator grill. Photograph besides road. Road straight. Test done on a closed military airport.
Controlled speed: 100 km/h (62 mph).
Starting photo burst at 100m distance (109 yards, 328 ft). Stopping when passing by.
Time to drive through 100m: 3.6s.
Focal length: 35mm equivalent of 200mm (135mm for K20).
Aperture: f/2.8 or widest (Olympus).
Shutter: 1/320 or shorter.
Light: Daylight overcast with grayness. Constant conditions.
Storage: JPEGs onto Sandisk Extreme III.
Statistics: 6 series, averaged.
Short verdict (mine):
While the K20 comes out last, it did do its job surprisingly well after reading all the complaints around. We all don't position the K20 as the sport photographer's machine gun and rightly so with only 20% of the available peak performance on the market (1D).
However, it is more than sufficient for everyday photography with ~75% of images in focus.
If I may make my personal scale:
Outstanding: 95-100% (relative ratio of in-focus shots)
Then I get:
Excellent: 40D, D3, D300, 1D, 1Ds
Good: E3, D80, K20
Nothing to complain about. Of course, this is a representative test for AF.C performance (probably the best been published to date). It is nowhere indicative for low light AF.S performance.
Note: If you found this reading worth your time, you may also like our forum friend's lol101 post here:
K20D AF tracking: a non scientific test.
He found a 96% in-focus rate for K20 vs. only 25% for K10.
The article contains more information. So if the discussion needs it, it may provide some more info (e.g., the D300 results were said to have shown large variations).