Hi,
this is my first post and a very basic one it is too ... could someone explain to me please the relative merits & disadvantages of 'standard' bidwatchers' binocuars with central focus versus the dual eyepiece focus of military style binoculars?
Also - and this is propably a very stupid question - if you make a dioptric adjuastment to the right eye piece in a standard binocular, what happens to the left eyepiece ?
thanks
Mike
Hi Mike, it's not really a stupid question if you're not familiar with modern binoculars.
The vast majority of modern bins have a central focus wheel, with an independent dioptre adjustment for the right eye. The independent dioptre allows differences between the observers right and left eye to be accomodated for (for example, I am shorter sighted in my left eye than my right. To compensate I need to set the right dioptre to +2, whereas someone else with an opposite differential between their eyes might need to set it to -2 or even -3.) It works best if you close your right eye, and focus for the left with the central wheel, then close your left eye and focus for the right with the independent dioptre. The beauty of this is that once best focus is set for both eyes, you can use the central focus wheel to maintain focus for both of your eyes for any object at any distance.
The obvious advantage of this is that it saves time. Imagine trying to locate a fast flying bird in your field of view (hard enough!) and get it in focus for both eyes separately before it disappears from view.
I personally have never come across a pair of bins with individual eyepiece focus, so I think it must be a relic from the military/navy. Perhaps they still use it on models specially built for their purposes, but I can't think of any reason to except that large ships move more slowly, and therefore allow the viewer more time to independently focus both eyes separately.
[QUOTE=SteveClifton;950652]I personally have never come across a pair of bins with individual eyepiece focus, so I think it must be a relic from the military/navy. Perhaps they still use it on models specially built for their purposes, but I can't think of any reason to except that large ships move more slowly, and therefore allow the viewer more time to independently focus both eyes separately.[/QUOTE]
The new Steiner Discover binoculars have a 'Dual Precision Setting' which allows each eyepiece to focused separately. I don't know what the advantages are or how it works though.
http://www.steiner-binoculars.co.uk...very%208x44.htm
I think there is a review of them in the equipment reviews section of this site.
Ron