[YMC]

婚禮拍攝禮堂相時，準備用兩枝燈45CT1夾580 EX II 用 EM Mode，發現了曝光會低兩級！我曾到門市換燈，但試過兩枝也同樣出現此問題，後來便拿去Canon維修，結果話枝燈冇問題！我便跟他們理論，我用美能達測光錶測光，美斯燈冇問題，580 EX II 曝光低兩級！但那裡的維修員說其他品牌的閃光燈，測光錶他們不會評論的，他們只管公司儀器測出的結果！所以感到很無奈！！
希望各位Canon 580 EX II 的用家是否也發現有這個問題？請大家發表一下！或者只是我本人的問題而已！！

[cy001]

我估的,你應該唔好用2枝美斯45CT1夾580EXII,改用2支580EXII代替就冇事,原廠加外廠,很多時候差少少,你都要接受,但你洗少了錢呀!人手加2級. ^^

[YMC]

我現在是用單一580 EX II 曝光低了兩級，如果夾45CT1反而冇問題，因為45CT1測光冇問題，會補夠光的！

[teddyso]

I hae similar problem when I used Canon 20D and 580EX, which was always under exposure.

I took them to the Canon service center. They put my flash into their camera. It worked well. They put their flash in my 20D, and it was under exposure again.

Therefore, there was some problems in the 20D body. After checking they said the program inside the 20D body was tuned down too much that caused the under exposure. After they tuned it up in their service center, it worked ok now.

You may bring your body and falsh to their service center, and ask them to do similar testings to see what goes wrong.

[YMC]

580 EX 與 580 EX II 有所不同，580 EX II 加入了舊式閃燈的外置電眼測光(EM Mode），他與 E TTL II 測光不同（需預閃），（EM Mode ）只靠外置電眼實時測光，完全不需與相機溝通的，因此不全在相機的因素，所以也可以夾到其他沒有 TTL 的閃燈，問題是出在580 EX II 閃燈身上！！！