Here is a quote of part of a post from expert Dave Atlas, as this should be of help to you. Basically the H&A viewer is used to look at symmetry and patterning and isn't used to determine leakage, an Idealscope will show any light leakage and symmetry / patterns.Date: 11/12/2008 1:21:54 PM
Author: nos96
it will be round. How does a hearts and arrows viewer differ from an IS? They look and seem to show a similar image but I am sure I am missing something. Do H&A viewers not show light leakage?