Sensational words

[maktau]

I see a man sitting in the park;
I see a man sit in the park.

Which one of the above is correct?
As far as I remember, sensational words (such as see, feel, hear) are followed by bare infinitive. Please tell me the rules, thank your for your help.

[Tdol]

I saw him do it = I saw everything
I saw him doing it = I saw part of the action but not all