[ultegra1980]

是否要質素好的鏡片才可做大光圈鏡頭所至?

[endlessmove]

因為大光圈多數係定焦，小幾組鏡！米清楚羅

[ultegra1980]

24-70 vs 24-105, are both zoom lens, but 24-70 F2.8 is better than 24-105 F4, why??????

[Xavierlo1679]

我諗24-70 vs 24-105 真係無日無止
24-70 利係唔夠 24-105 利 (MTF)
無謂日日夜夜比較邊支好邊支勁

better 既意義好多
你係拍 PQ 吧?
24-70 同24-105...人眼真係好難分
如果同銳利度 同MTF 比...24-70 真係唔夠 24-105 利
咁又點會 : 大光圈鏡頭影像質素會好D

如果大光圈鏡頭「影像質素」會好D中的「影像質素」係指景深
咁大光圈鏡頭影像質素會好D係成立的

[layer]

影相唔係單一淨睇MTF.
全方位影像質數計
24-70L 100% 靚過24-105L

[layer]

兩支我都有, 不過我唔會去吹毛裘, 邊支用得着咪帶邊支出去用囉.

[layer]

sorry , wrong post

[jsklee]

"24-70 同24-105...人眼真係好難分"

I disagree.

Here are two sets of photos used by the two different lens.

http://www.pbase.com/middlehill/elsa_and_wilson
http://www.pbase.com/middlehill/smk

Although some of the photos were post-edited, but I deeply believe that most of you could differentiate which album is sharper than the other.

[wesleyyau]

24-70 收到F4 同24-105 F4去比...
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=101&Camera=453&Sample=0&FLI=0&API=2&LensComp=355&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=0
24-105 @F4 可以同24-70 @F4 有得比係新鏡質量始終有進步... 所以我一向都話24-70係時候出II 代... (大三元完成更新) =P
回返樓主問題... "點解大光圈鏡頭影像質素會好D?"
唔計定焦... 大光圈鏡頭一般都用3倍倍焦樓下... 成像比5倍或更高倍焦o既鏡頭更好... 另外鏡頭最佳光圈都係鏡頭收二至三級光圈左右...
舉例f2.8 鏡收到f5.6已經好sharp... f4鏡頭可能要收到f8先至sharp... 當然呢個冇一定... 因為仲要睇支鏡本身鏡組物料... 例如螢石/UD等等...

[h0001244]

再加上這是市場定位.......
F2.8鏡片大塊D，造價貴D，賣時一定會定價高一點點，但如果只是大了一級光圈而成像不變，就無左differentiation的作用，咁就唯有更上一層樓用上上乘 UD 螢石等鏡片增加其賣點，做成頂級的感覺，吹之若慕，好似就算貴了五倍都物有所值。

[ssannwong]

agree with h0001244 ching,

鏡頭要大光圈, 鏡片一定要大塊d配合, 但用料多左成本一定又大左, 成本大左鏡頭難免又要買貴d, 既然都要買貴d, 不如做好埋d光學設計, "頂級化"d大光圈鏡頭~

[h0001244]

when you compare 50.8, 50.4 and 50.2
it's not just the enlarging the lens opening and lens pieces, also the quality of glass, coating, aperture blade, motor, the material used (plastic or metal)...etc
all these make you feel that 5 times you pay for 50.2 among 50.4 is worth to do so.

[roy05]

光圈夠大, 可以啟動相機更準確對焦, 如十字, 雙十字, 因此對焦準確度已經可以接近double, 張相利d, 感覺都質素好d

[swhsimon]

Logical Speaking this statement ---- is NOT true.

a. Big F and Good Quality is No Direct Relation.
Big F --> Good Quailty , ( Not True)

b. Big F , no need to remind everybody the definition.

c. Good Quality---> More expensive ( it is always True)

d. Bigger Size of Glass--> Expensive Lens ( Not always True )
( since , the main factor is Optical Design ,not glasses)

Good Quality is depend on Optical Design , knowledge is expensive

=================================================


Satement 2: Design Smaller F is more easy than Bigger F e.g (f1.2 vs f5.6)
Reason: Light in Bigger Glasses outer is difficult convet to center axis, it means easy distortion

=====================================================

Statement 3: In the same lense
the 1 to 2 step Smaller F will better than Max F

Reason: Use the Aperture Frame to cut out the border distortion Light physically

example, F1.4 Lense cut 1 or 2 step to 2.8 then become more good

====================================================

Conclusion: They have NO direct relation ( logically speaking)

===================================================
Sorry, Say So Much ,