[路基亞]

我仲係新手......怪我無知吧

為甚麼遠攝時光圈一定會細了？

[Velsper]

你指影風景?
一般細光圈有兩個作用
一:以135來說,鏡頭最佳解像力多數在約f11
二:影風景通常你都想"全張相都sharp", 細光圈,深景深就有幫助.

^__^

[路基亞]

不是這個....但也多謝你....

是zoom最遠時，光圈一定會收細.......是設計上的問題？

[路基亞]

不是這個....但也多謝你....

是zoom最遠時，光圈一定會收細.......是設計上的問題？

[Edward Yeo]

拍人像要zoom到最大,光圈也最大,才能有浅景深的效果是吗 ?

[tam_dominic]

是, 設計上的問題.

In most design of zoom lens the longer zoom in the smaller aperture.

As an exception Panasonic FZ1 has fixed F2.8 even zoom all the way in at 420mm.

Happy shooting !

[Ekamz]

冇錯,事實上只有 Pro
既 DC 0係 zoom 既時候都 fix
死 ,而一 d 有光圈,快門先決既細機,
一zoom 個光圈一定會變細

[tam_dominic]

Edward,

There is an interesting experiment for you.
1. Take 2 shots with the same wide open F stop.(eg F2.0)
2. One at widest angle (eg 35mm) and the other one at longest zoom (eg 200mm)
3. Move the DC so that the subject occupy the same area of the frame. with the same background.

Compare the sharpness of the same distance in the 2 photo. (ie Depth of field)

You will be surprised the depth of field at 35mm is the same as at 200mm ! Please tell me if I'm wrong.

This experiment costs you only fun time.
By the way don't expect any consumer DC can give you shallow depth of field unless at macro distance.


Happy shooting !

[Velsper]

係dc上較少有恆定光圈
其中原因為鏡頭設計難度
二為相機大小問題
(如135機上的恆定光圈鏡比不恆定的重了多少??口徑大了多少?)
三當然是價錢問題囉~~

(sry 會錯意~~)

[路基亞]

多謝咁多位0既講解 ^^

[路基亞]

多謝咁多位0既講解 ^^

[hkhei]

tam_dominic
在固定成主體大小o既情況下
焦距幾乎不影響景深的..

不過長o既焦距會令背景更朦

[ZeissIkon]

廣角時，周圍光線教較易入鏡，
Tele時，只有主體在取景框內，
曝光值多數有分別的了。

[tam_dominic]

If "在固定成主體大小o既情況下
焦距幾乎不影響景深的.." stands correct then

Since背景更朦 is not cause by depth of field , then what cause 長焦距會令背景更朦?

Just curious ;-)

Happy shooting !

[sevensister]

相同光圈, 相同畫面比例下, 就算焦距不同, 景深也是不變的

長焦距製造的是"散景"效果
跟"淺景深"是兩回事

小弟淺見, 如有錯漏請不吝指正, 謝謝 :)