In any case, the optics are of very high quality. The optics employ Pentax's "Super Multi-Coatings" (SMC) and field flattener lenses.  The coatings do appear to be top quality, and the prisms also appear to be multicoated.  The image is bright, with minimal spurious light leakages or reflections.  This is one of the few binoculars I have seen that can be focused for a sharp image across the full field, not a simple achievement for such a moderately wide field of view.  It does require careful focusing to achieve this, especially at night with demanding pinpoint star images (also, I believe that the larger exit pupil at night reduces the eye's depth of focus).  Thus the field is not perfectly flat.  Also note that the apparent flatness of field may be affected by an individual's ability to accommodate the difference in focus from the center to the edge of field.  There is a bit of pincushion distortion visible towards the edge of field but this is not really an issue.  Also, I can detect a small amount of lateral color (again, not bothersome).  One optical parameter that I wish could be better on this binocular  is the eye relief.  Although better than average, it is not quite enough for me to see the full field of view with glasses on.