Not sure what else to call it. I have a 16" fixed front sight flat top. With eye relief set correctly I am seeing a beveled edge effect. The inner 80% of FOV is perfect. On the outer edge I see an angled reflection effect. Imagine looking at a round mirror with a beveled, mirrored outer edge. It looks like that except of course i see downrange. It's seems to come and go as I try to focus on a reticle in every scope I have tried.
I have astigmatism and am nearsighted. I do wear corrective glasses and did for this test. I am an experienced shooter and my bolt guns do not seem to bave this problem with typical 'deer' rifle scopes. The optics tested on my ar all had objectives in the 20mm range - I am not sure this is a factor (% obstruction from front sight). Any suggestions would be appreciated.