I have a pair of reasonable quality roof prism binoculars, 8x25 and claimed to be waterproof. I bought them, new, about 3-4 years ago. How can I tell whether they have phase coating by simply looking through them?
So far, all I've noticed is that they're nowhere as easy to use, simply because their exit pupil is much smaller than my larger porro prism bins. However, they are compact and slip into my pocket easily, and thereby fulfil the reason for purchase.
Cheers,
[QUOTE=Malcolm Stewart;885055]I have a pair of reasonable quality roof prism binoculars, 8x25 and claimed to be waterproof. I bought them, new, about 3-4 years ago. How can I tell whether they have phase coating by simply looking through them?
[/QUOTE]
Hold the glasses at roughly half arms length and look through the objective lenses. Non-phase coated prisms will show a faint line across the image at the equator while the phase coated models will not. The effect is easier to see with larger objective lenses, but it still should be visible with 25mm objectives.
Thanks for your quick response. I've done what you suggested, and against grey rain clouds (we're now getting the rain that should have fallen last month!), I can't see any suggestion of a line. (The bins are 8x25 compact Minolta Activas, and claim to be fully multi-coated with BAK4 prisms.)
Many thanks