Explanation
Indicates a contrasting or inconvenient timing; 'just when...', 'even though...'.
Formation
Verb-ている + ところを / Noun + の + ところを / い-Adjective + ところを / な-Adjective + な + ところを
Detailed explanation
The grammar point ～ところを is often used when something happens (or one acts) at a certain moment/condition that makes the timing inconvenient or contrary to what is expected. It can imply “in spite of the fact that...” or “just when...” depending on context.
Examples
Choudo eiga o mite iru tokoro o, teiden de makkura ni natta.
Just when I was in the middle of watching a movie, the power went out and everything went dark.
Oishiku tabete iru tokoro o, kare ga zenbu yokodori shite shimatta.
Right when I was enjoying my meal, he took it all away.
Hikouki ga ririku shiyou to shite iru tokoro o, kyuu ni enjin ga tomatta.
Just as the plane was about to take off, the engine suddenly stopped.
Kanojo ga okotte iru tokoro o, watashi wa joudan o itte shimatta.
Even though she was angry, I went ahead and made a joke.
Practice
Grammar content sourced from hanabira.org.