標題: f/2.8 問題 A16 (p2 Post #17 updated with pictures cp) [打印本頁]

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作者: lsman1    時間: 2008-10-7 10:56     標題: f/2.8 問題 A16 (p2 Post #17 updated with pictures cp)

--EDIT: pls see page 2 #17 and onwards for some comparison.

http://www.flickr.com/photos/lsman/sets/72157607803978288/

其實 f/2.8 用來室外,
IMG_2709
http://www.flickr.com/photos/lsm ... -72157607803978288/
IMG_2710
http://www.flickr.com/photos/lsm ... -72157607803978288/

screen/ monitor 好像可以清晰
但一 close up  (100%) 就好 blur..
http://www.flickr.com/photos/lsm ... -72157607803978288/

1.新鏡 + 新手 (f/2.8),所以唔知係唔係自己問題...
2.應該用 f/4 or larger ?
3.張2904
http://www.flickr.com/photos/lsm ... -72157607803978288/
放100%時都 ok... 但DOF 好少...即係個鏡冇問題?

先多謝

[ 本帖最後由 lsman1 於 2008-10-9 21:06 編輯 ]

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作者: 愛神    時間: 2008-10-7 11:02



我諗室外影用F2.8有地方唔清係因為DOF問題...收細D會好D...如果你用A mode既話就收到shuttle岩岩夠freeze到全部人既動作就最好 (以你post出黎個張為例), 當然你想有特別效果又另計啦..

同埋個最尾個張, DOF 淺係正常架喎...F越大, focal length越長, DOF越淺架麻...

我新手有錯請插

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作者: ahshing    時間: 2008-10-7 11:05

其實鏡頭通常收少少光圈就sharp，我有大光圈鏡都唔會成日用盡最大光圈
好似24/2.8，28-70/2.8好多時我都係收到f3.5-4先用，而70-210/4我又會收到f5.6用(如果唔係要佢既散景溶d既話)

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作者: inzite    時間: 2008-10-7 11:12

softness at 100% is due to ur lens optic quality at maximum aperture.  the dof at f2.8 should be similar to wat u have shown and usually lens performs best in the middle of the zoom range, usually softer at either end of the zoom.

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作者: fresh_banana    時間: 2008-10-7 11:13



我用A16 , 係室外(夠光)都係用 F4多, 用2.8真係會淺過頭, 好似 outfo. 咁

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作者: inzite    時間: 2008-10-7 11:16



it's not due to "out fo" the softness is due to the reason i mentioned above.

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作者: ahshing    時間: 2008-10-7 11:21



你用支a16既50mm/f2.8，同一支50/1.4既f2.8，出黎質素都係唔同的
未必關dof事
再講，50mm/2.8既dof叫淺，咁300/2.8咪永遠都對唔中?

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作者: lsman1    時間: 2008-10-7 11:38

遲吓用18-55is kit lens 比一比..
我初步比好似 kit lens (f5@43mm, vs a16 f6.5 @31mm
both at 1/60 flush) 比清晰d

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作者: inzite    時間: 2008-10-7 11:46

try them at the same focal length at the same aperture and set it on a tripod shooting the same thing.

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作者: chun__:)    時間: 2008-10-7 11:48

如果kit lens 是good copy 的話 sharp 過a16 都唔出其. 不過a16 係恆定f2.8...應該比kit lens 好玩
http://www.photozone.de/canon-eo ... ort--review?start=1

http://www.photozone.de/canon-eo ... ort--review?start=1

得閒既話可以試埋focus chart 睇下準唔準焦
http://www.dchome.net/viewthread.php?tid=284785

[ 本帖最後由 chun__:) 於 2008-10-7 11:52 編輯 ]

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作者: lsman1    時間: 2008-10-7 11:49




We should have a "readme" sticky... to teach how to test a new toys... I mean lens.

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作者: manman1998    時間: 2008-10-7 11:54


正有點想18-55is kit 同 A16 二選一

18-55is kit 平一倍多

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作者: lsman1    時間: 2008-10-7 12:02

buy it online... can't test it till it comes... so that's an disadvantage.

If you can test the copy first, it will be great.

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作者: inzite    時間: 2008-10-7 12:15

i buy all my gears in stores except my mark3 which i bought at bh. no problems with any gears so far.

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作者: sniperX    時間: 2008-10-7 12:59



呢個易試同準Ｄ。

http://www.dchome.net/viewthread.php?tid=575002

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作者: fresh_banana    時間: 2008-10-7 13:21



你睇清楚我寫咩先 "好似 outfo. 咁"

我知唔係outfo. , 但有冇走蕉我就唔敢品評啦  

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作者: lsman1    時間: 2008-10-9 12:15

Ok here we go...
Tested... all my lens at vary f and s..combo..
iso100, AWB, same distant from wall of newspaper, use tripod and remote release...etc
crop 800x600 of center, left and right side...
Models:
A16 (A), Canon 18-55IS kit lens (B), Canon 50mm 1.8 (C), Canon 55-250mm IS (D)
(A) 50mm 1/6s f8
(B) 55mm 1/6s f8
(C) 50mm 1/6s f8
(D)55mm 1/6s f8
Center
(A)-

(B)-

(C)-

(D)-


------------------------------------------
Left side
(A)-

(B)-

(C)-

(D)-


---------------------------------------------------------------------------------------------
Right side:
(A)-

(B)-

(C)-

(D)-

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作者: inzite    時間: 2008-10-9 12:19

and wats ur conclusion?

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作者: lsman1    時間: 2008-10-9 12:22

at f8, A16 looks sharper...

...

I am loading the others...

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作者: lsman1    時間: 2008-10-9 12:31

(A)17mm 1/6s f8
(B) 18mm 1/6s f8
-----------
Center
(A) -

(B)-

------------------------------------------------------------------
Left
(A)-

(B)-

-----------------------------------------------------------------
Right
(A)-

(B)-

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作者: lsman1    時間: 2008-10-9 12:33

Is it me or do you think at the wide end, the 18-55IS kits lens is actually a bit better?

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作者: lsman1    時間: 2008-10-9 12:55

For the middle range... let's "compare" something differently... you may say its not apple to apple.. but.. lens softness at ends of zoom... but how about max aperture at middle of zoom? and what about 50mm1.8 at f2.8?

(A) 24mm 1/50s f2.8
(B) 28mm 1/25s f4.0
(C) 50mm 1/50s f2.8

----------
Center
(A)-

(B)-

(C)-

----------------------------------
Left
(A)-

(B)-

(C)-

-------------------------------------------------------------
Right
(A)-

(B)-

(C)


-----------------------


again,... is it me (too high expectation? wrong approach?) or the f2.8 at middle zoom still look bad..
or it should be that bad?

[ 本帖最後由 lsman1 於 2008-10-9 13:00 編輯 ]

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作者: inzite    時間: 2008-10-9 12:58

possibly too high expectation from a prosumer lens like tamron. :P u have to see my 24-70 crops :P

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作者: lsman1    時間: 2008-10-9 13:06

Last set...

(A) @35mm 1/50s f2.8
Center...still ok..


Left

horrible...
---------------------
Right

...surprise... better than left side....

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作者: lsman1    時間: 2008-10-9 13:07



Any A16 user input...?

Thanks.

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作者: Yoda    時間: 2008-10-9 14:23

No surprise, very few lenses can be at its best wide open.

Even my 400/2.8 needs f4 to be really sharp.  The only lenses I would not hesitate to use wide open is the 500/4 VR and ZP 85/1.4.

The Noct also needs stepping down to f1.4 to get maximum sharpness.

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作者: lsman1    時間: 2008-10-9 21:14


If kit lens can do what the A16 can do, while the f2.8 is a waste... why do I need to pay double for it...



@f8 they are close enough (A16 a bit better if you will)


and yeah, prime lens are just plain "sharper" in those area.

[ 本帖最後由 lsman1 於 2008-10-9 21:15 編輯 ]

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作者: lsman1    時間: 2008-10-9 22:00

I think I need to take it outside and work it a bit...

Let see what "real life" pictures it will be at f4... (with better lighting)

http://photography-on-the.net/forum/showthread.php?t=209580

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作者: Ch!sE    時間: 2008-10-10 00:19


我係用家之一
不過我通常我都唔會全開2.8
返一下就已經係靚好多
影風景, 真係收到F8以上囉
同埋我覺得無乜一支鏡全開光圈會sharp得交關...
有需要不如上鏡皇吧啦

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作者: 新遺失戰艦    時間: 2008-10-10 00:23



要光圈盡開, 而又sharp, 只有鏡王級既定焦先做得到

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作者: ALLEX    時間: 2008-10-10 00:36

A16有覺得sharp小小,最小要收到f4

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作者: westkenny    時間: 2008-10-10 07:55

之前用咗A16 1Week(放咗),A16有偏色see pic post 17#,同原廠比更嚴重,加480/540EXII Bonus仲偏得跨, 轉咗Sigma 18-50/f2.8 marco ex就正常哂!

[ 本帖最後由 westkenny 於 2008-10-10 07:58 編輯 ]

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作者: AAA1    時間: 2008-10-10 08:25

Right, the colour of A16 looks too brilliant. There is also focusing problem once in a while. And other website test revealed the focus plane is not flat but a curve instead. So it is normal for it to be blurred at corner, but sometime one side is more in focus than the other side. It is a weird len.
The other new purchase Tamron len I get is 90mm macro, another weird len with focusing problem, and showing vessels underneath skin on portrait.

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作者: inzite    時間: 2008-10-10 09:07

u need to try a 24-70 nikon or 24-70 canon to feel the difference.

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作者: AAA1    時間: 2008-10-10 10:01

http://www.photozone.de/Reviews/ ... 750_28_sony?start=1
see a review for alpha mount

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作者: lsman1    時間: 2008-10-10 10:04





Blood...Run!...

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作者: AAA1    時間: 2008-10-10 10:10

I agree with you that the focus depth seems too shallow for A16 compared to other old SLR lens I get.
For 90mm macro, the len just exaggerate any defect you can find on portrait. Even a small flake of skin piece is revealed. I suppose the len is sensitive to infra red so that superficial vessels become more prominent.

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作者: ahshing    時間: 2008-10-10 12:51



你覺得太鮮?我覺得太灰wor

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作者: lsman1    時間: 2008-10-10 21:26

I think the color is more "pink"....

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作者: lsman1    時間: 2008-10-11 09:44

for what it forth...outside shot


F10 1/80s


f5.6 1/250s



f5.6 1/50s


f5.6 1/100s



a bit soft on edge...
f2.8 no use under sun light...
it will match with 1/1250s and the image will be blur on far object..