What causes blackouts and what brand and types of binoculars do you think are the worst.
Dennis
[QUOTE=denco@comcast.n]What causes blackouts and what brand and types of binoculars do you think are the worst.
Dennis[/QUOTE]
Dennis,
If you mean what I think, blackout is caused by that your eye comes too close to the lens. This is usual with optics with a very long eye relief and isn't a sign of poor quality. Sometimes people use too define this as "too long eye relief". There isn't too long eye relief, however, but there are eye cups who are not possible to adjust to an optimal level. A strict technical explanation of the reason to blackouts I cannot give, but there are surely they who can!
Patric
Long eyerelief combined with wrong adjustment of the interpupilary distance. Another factor is softness/firmness of the eyecups (soft eyecups make it more difficult to hold the binoculars correctly and avoid blackouts).