When Does Isha Time End

I want to know how late can one say Ish'a Paryer. Someone told me that it's better to pray qada salat after midnight. Can we say our Ish'a pryer after 12:00 if in case we can't perform it in jaa'mat?
 

The permissible time to perform Isha salat is untill subh-sadiq (true dawn). To perform Isha salat after half of the night has passed will be considered makrooh (undesirable). After midnight one can perform salat, and this will be considered performed in its valid time (ada), not qada. Half the night can be calculated by finding the midpoint between sunset and subh-saadiq. (Fataawa Mahmoodiyah vol.2 pg.146, 240). And Allah Ta'ala Knows Best