[alvincyt]

即係話, ISO50加兩秒曝光, 同ISO100加一秒曝光, 效果係咪一樣?

[Terry Hon]

應該係多一級.
e.g.when u are using iso50, the shutter speed is 1/125 and the aperture is F8.0, then when u are using iso100, if the amount of light is the same, the aperture is F8.0 and the shutter speed is 1/250.(in aperture priority mode)

[老叟]

計正來講,比iso64先至係o岩o岩高一倍!!

[jackngai]

計正來講,比iso64先至係o岩o岩高一倍!!<<<<<<<

唔明..........

ISO1600 --->800--->400--->200--->100
以上全部一級級咁落, 點解 100 之後唔係 50 , 而係 64呢?

[Kelvin KC Chan]

If ISO 50, use f5.6; when ISO 100, you can use f2.8.
The shutter setting is depended on what f you use.

[Kelvin KC Chan]

Sorry, this is correct : if ISO 50, use f2.8; when ISO 100, you can use f5.6.
Sorry again.

[Velsper]

>>if ISO 50, use f2.8; when ISO 100, you can use f5.6.
補充少少~
在相同快門速度下

>>計正來講,比iso64先至係o岩o岩高一倍!!
老叟兄, 你是否指菲林實際感光值不足的問題?

[ftslee]

Kelvin兄，ISO 50 如果同 ISO100 差一級
咁光圈唔係f/2.8減一級即係f/4咩？

即係f/1.4 -> f/2 -> f/2.8 -> f/4 -> f/5.6

每一級數差 sqrt(2)

有冇計錯數？

[ftslee]

係喎，資料來自dpreview.com

http://www.dpreview.com/learn/Glossary/Exposure/Exposure_01.htm

同一快門及ISO之下，每 sqrt(2)的光圈值相差一個EV

[ftslee]

即係話alvincyt 兄所講係冇錯，同一光圈下ISO100同ISO50係要相差一陪曝光時間？

關於ISO…我都唔係好明點解會唔係ISO50而係ISO64呢？

其實照計ISO係一個standard，我都唔明點解係dpreview.com裡面比較Olympus C5050同G3時會有此說：

This test was made far more complicated by the G3's higher than reported sensitivity. In effect the G3 was a full stop more sensitive than the C-5050 Zoom at the same indicated ISO, this meant that the G3 was shooting with a 1/50 sec, F4.0 exposure at it's ISO 50, the same exposure as the C-5050 Zoom at ISO 100. Thus to fairly compare the G3 and C-5050 Zoom we must compare crops from each camera a stop of sensitivity apart.

詳見 http://www.dpreview.com/reviews/olympusc5050z/page15.asp

有冇朋友可以解說一下？

[Elliott]

"As we've noted previously Canon's indicated ISO 50 is fairly conservative, indeed for the G3 I would put that indicated sensitivity closer to ISO 80."

詳見 http://www.dpreview.com/reviews/canong3/page16.asp

(Oh.... 我仲以為ISO value係個個都一樣tim.... 原來Canon係高少少個喎...)

[Kelvin KC Chan]

Hello ftslee,
Thanks to post the correct idea:
即係f/1.4 -> f/2 -> f/2.8 -> f/4 -> f/5.6
I check the " Bible" find what I said is wrong. : ( ha...ha... : )
Thanks again : )

[kevin_chiu]

re elliott

其實直情差一個stop..

[hkhei]

一個stop即係一倍