Why was this usage of ところ incomprehensible?

Question

I am an intermediate-level student, studying in Japan. All teachers are native Japanese speakers.

I was asked to write an example sentence using "ところ", using it to express a temporal concept such as "about to," "while," etc.

I decided on the following sentence, in English:

When I was about to buy a manga, I noticed that it was the wrong volume.

To me, this is somewhat abstract, but clear enough: either in a physical store, or online, I was about to buy something when I realized I had made a mistake.

In Japanese, I expressed this as:

漫画を買うところを、巻が違うと気づいました。

This was so incomprehensible to my teacher that she came over to my desk urgently during class to explain how I was using the wrong kind of ところ (I'm not sure what she was getting at as she later erased her initial notes). I'm aware that there are secondary grammatical errors here, but please read on.

The only way I was able to explain it to her was to physically act out and narrate the act of walking up to a register, looking at a book, and realizing a mistake. This was still so surprising to her somehow that she took until the next day to come back with this rewritten sentence for me:

漫画を買うためにレジに並んでいたところで、ほしかった巻と違うと気づきました。

In English, I read this as:

When I had just gotten in line to buy a manga, I noticed that it was a different volume from what I wanted.

This is certainly much more concrete and detailed, but what is it about my initial construction, 漫画を買うところ, that was so confusing to a native speaker? How would my original idea, "about to buy a manga," be expressed in Japanese, if not this way?

Thank you.

Answer 1

As the final correction by your teacher suggests, you chose the wrong particle, and that caused the confusion more than anything else. The particle should be で to denote the circumstance in which you realized your mistake. Correcting that and changing 気づいました to 気づきました, we get the following.

漫画を買うところで、巻が違うと気づきました。

This sentence is not at all incomprehensible. I’m not sure why it took your teacher so long to understand what you meant. However, without enough context, people might understand this ところ as referring to a concrete place where comics are sold. If your listener already knows you nearly bought the wrong volume of a comic and asked you when exactly you realized your mistake, then the sentence sounds natural enough as a response (though you might omit 巻が違うと in that case). If you are saying it to someone who doesn't know you were going to buy a comic to begin with, you should probably say:

漫画を買おうとしたところで、巻が違うと気づきました。