This question itself is a bit misplaced, because Isight doesn't make use of any of the Java installations you may have on your machines. Instead Isight comes with its own JRE. It is usually available under a folder similar to :

C:\\SIMULIA\\Isight\\5.5\\bin\\win64\\jre

or

C:\\SIMULIA\\Isight\\5.7\\win_b64\\win_b64\\code\\jre

To determine what java version your Isight installation is using, run the java -version command using the java executable available in the Isight installation, like in the below figure :

Following is the list of java versions that are available with various Isight releases :

Java 1.6_028 translates to Java 6 update 28. Dont ask me what happens to the 1 in-front of the version number. Ask Java.