ならいざ知らず
(Nara iza shira zu)
if it were X, I wouldn't know / X might be one thing but.
Connection rules
- +Noun / plain form + ならいざ知らず.
- +Contrastive exception — 'X might be a case where I couldn't say, but Y is clearly not'.
- +Similar to 〜ならまだしも but slightly more dismissive.
Examples
1.
子供ならいざ知らず、大人がそんな失敗をするなんて。

Kodomo nara iza shira zu, otona ga sonna shippai o suru nante.
If it were a child I wouldn't know, but for an adult to make such a mistake!
「if it were X, I wouldn't know / X might be one thing but」
2.
初心者ならいざ知らず、プロがミスするとは。

Shoshinsha nara iza shira zu, puro ga misu suru to wa.
For a beginner, maybe — but for a pro to make a mistake!
「if it were X, I wouldn't know / X might be one thing but」
Practice
In the old days it might have been different, but in this day and age, that kind of thinking is outdated.
___、今の時代にそのような考え方は通用しない。
Romaji also accepted