請看一下這篇各相機對焦評測：
Summary:
- 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.
Results
Gear:
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)
Method:
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)
Excellent: 85-95%
Good: 75-85%
Average: 25-75%
Poor: 0-25%
Then I get:
Outstanding: A700
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).
Enjoy.
原文出處
http://www.pentaxforums.com/forums/pentax-news-rumors/25521-magazine-review-k20d-sdm-af-c-performance-vs-8-competitors-good-info.html
，不同級倒是實話...一個目前還是未來品(50D)，一個是過去品(D300)，
iamina wrote:
我來用我個人所了解的...(恕刪)
剛剛GOOGLE一下關於D300 VS 40D 僅針對對焦點部分跟連拍速度跟對焦速度來比較的資料
參考網頁
http://yuedu.sdnews.com.cn/2007/12/11/356534.html
40D對焦速度優於D300的參考資料
http://tw.knowledge.yahoo.com/question/question?qid=1608061600971
40D的九點對焦點都是十字高精準度對焦點尤其所有九個點的對焦速度都非常平均而且都非常的快,優於D300,E3,α700,
其中最大致命傷就是D300雖然支援14bit RAW但是此模式下連拍速度就只剩3fps,反觀40D再此模式下一樣可以達到6.5fps,就光這幾點50D表現肯定優於40D,起碼也會跟40D一樣,就光RAW連拍速度無法達到6.5fps跟對焦速度無法比40D快之下應該還是50D是不錯的選擇了.
沒辦法拍飛羽尤其拍山鳥對焦速度更是需要,這關係到成功率,有些時機稍縱即逝,對焦速度慢一點就會讓你喪失機會,加上raw連拍速度是必定要求的因此50d還是目前比較有利的選擇對於生態攝影而言.
iamina wrote:
那樓主綜合你我的認為...(恕刪)
Hachen的文章裡有E3啊, 我看不出哪裡不下C, N了
另外dc watch還有Olympus相機測試
看過你可能會覺得: 哇E3對焦系統這麼糟糕啊?
不信請點此
註:
用150mm鏡頭對焦在7-8m遠的地方, 每次都把鏡頭轉到無限遠的位置, 然後按快門重新對焦拍照
結果50張照只有19張是perfect的, 10張是縮圖50%後還ok的, 21張是縮圖50%也不ok
這還是拍靜物, 要是拍動態會怎樣呢
Reason is simple: those Nikon super-teles are way too expensive! And they are diffcult to buy.
I consider a 50D or a D300 as accessories for those lenses. If you are buying those super-teles, why choose bodys first? Choose lenses first. Than just buy whatever body that mounts. Those bodys are too small a factor (both in price and in weight/size). Unless you have some D3s or 1Ds.
EOS 40D+BG-EN3/350D/17-40 f4L/70-200 f4L IS/50 f1.8/18-55 f5.6/MacBook&ThinkPad
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