[xtr]

本人買左支EF 100-400mm f4.5-5.6L IS USM ...之後去買個canno ga1.4x點知一装左上去一試....由140至560mm全程無左自動對焦但有is....唔知點解.....光圈又冇over 8光圈......有冇師兄可教路thx!

[beancurdbean]

支鏡有無揀?MF制??

[kevinhon]

要canon 1系列機身, 才可在最大得F8光圈下自動對焦, 其他機身要有F5.6才可以!

[GATO]

書都講明冇自動對焦啦......點幫你呢~~~

[Obi-Wan]

1.4X or 2.0X extender produces good photo only if
(1) prime lens (not zoom lens) is used
(2) the f-stop of the lens is small (i.e. large aperature size), because after using 1 (for 1.4x) & 2 (for 2x) steps, the smallest f-stop becomes 5.6 to even 11, if we want to step down the lens to achieve better quality, DIFFRACTION problem occurs
MORE OVER, the autofocus really does not perform well at beyond f5.6 or 8.

I think CROPPING may be a better solution than using extenders

[delcam]

Hi,

你可以disconnect其中三點就可以有自動對焦,
不過唔記得係由左至右定右至左啦!

[cfans]

C兄是否買在打雀?

[dkmok]

我記得我係show room用350d試小小白加2x都得，可惜搵唔返相