Why the ISNA prayer times are not correct

The ISNA prayer time method was never an officially recognised method among scholars. Since the prayer times in North America are similarly late in the summer as in Europe, this method was introduced as a convenience. Originally, it was merely a recommendation. By calculating the prayer times with a 15-degree angle, the times for the Isha prayer were brought forward and the Fajr prayer was pushed back. However, the aim was not to determine more precise prayer times, but merely to simplify matters.

This is also evident from the fact that the time span between Maghrib and Isha, as well as between Fajr and Shuruq, is exactly the same length. If these were the correct times, the time between Maghrib and Isha would have to be shorter, since the start of the Isha prayer occurs with the disappearance of the last twilight and not with complete darkness.

Interestingly, ISNA changed its recommendation in 2010 and set Fajr to 17.5 degrees. Why the ISNA times are still given as 15 degrees on the internet and in numerous apps, however, can only be explained by the ignorance or negligence of the providers.