[teddyso]

I have just bought a Canon lens and I have found a focusing problem.

20D + 70-200mm = Auto focus ok
20D + 2x + 70-200mm = Auto focus ok

20D + 180mm Marco = Auto focus ok
20D + 2x + 180mm Marco = Auto focus NOT ok

I have to manually focus the 20D + 2x + 180mm Marco.

Is it normal? Or is there anything not function properly? I have tried using another body, but the problem still persists.

Thanks.

[iwkwong]

is that your 70-200 is f2.8 is or f2.8 or f4 ?

[teddyso]

It is a 70-200 f2.8

It works fine.

Just do not know why 2x + 180 Marco cannot be focused automatically.

[gaiuswong]

Marco鏡對焦通常都比一般鏡慢同冇咁便捷,你仲加埋2乘.....2x + 180 Marco cannot be focused automatically睇下說明書規格有冇提過加左2乘之後有冇咩限制,我估係正常掛,我都有EF180~f3.5Marco,但未試過要到加埋2乘既須要,不過我用得EF180~f3.5Marco就算冇加2乘都係會用手動對焦多.

[teddyso]

I bought the 2x is for the use in other lenses ( 70-200 and 135).

The manual only states that it can be used for all L series lenses with focal length more than 135mm. Therefore I tried it on the 180 marco lens and found that the AF did not work.

If it is normal then Canon should amend its manual.

[bt_boy]

20D + 70-200 係 70 時怕唔怕會有失焦呀?
因為我都打萛買 20D + 小白.

[gaiuswong]

唉!你唔好野野好似D友做測試下下塭把尺度住,爭幾多mm咁咪唔會失焦囉,唔係最top model如 1系既機我都唔會信佢張張focus都百份百準,靠多D自已對眼睇下好過完全信哂或靠佢哂自動對焦啦.

[kahox02]

I had 70-200 f/2.8L,
and since it did not work well (back-focus) with my 10D / 20D,
I took back to Canon Service Center,
they said there are some parts need to change,
and they kept my 70-200 f/2.8L for more than a month already.
>.<

Canon Focus Problem is very series.

[kahox02]

Very Serious