Changes

'''Binoculars''' are an [[optics|optical]] aid used to view distant objects with both eyes, such as scenery, wildlife, or far off boats or ships. They can also be employed in basic [[astronomy]], in lieu of a [[telescope]].

'''Binoculars''' are an [[optics|optical]] aid used to view distant objects with both eyes, such as scenery, wildlife, or far off boats or ships. They can also be employed in basic [[astronomy]], in lieu of a [[telescope]].

They consist of twin barrels containing a system of lenses one for each eye.  Because the distance between the eyes varies from person to person, there must be provision for adjusting the distance between the binocular's eyepieces; this is done by hinged the barrels together.  

They consist of twin barrels containing a system of lenses one for each eye.  Because the distance between the eyes varies from person to person, there must be provision for adjusting the distance between the binocular's eyepieces; thus the barrels are hinged together.  

While most binoculars are simply designed to be purely functional, opera glasses are a kind of binoculars that are usually rather [[ornate]] in finish.  They are used to improve the patron's view of the action on [[stage]].  The fancy form fits in with the formal nature of a performance and the highly decorated interior of most [[theater]]s.

While most binoculars are simply designed to be purely functional, opera glasses are a kind of binoculars that are usually rather [[ornate]] in finish.  They are used to improve the patron's view of the action on [[stage]].  The fancy form fits in with the formal nature of a performance and the highly decorated interior of most [[theater]]s.

A binocular usually has three settings. One of them is used to change focus the binoculars on objects of different distances. The other two are personal settings which vary from person to person but which, for any person, only need to be set once and do not need to be changed subsequently.  

A binocular usually has three settings. One of them is used to change focus the binoculars on objects of different distances. The other two are personal settings which vary from person to person but which, for any person, only need to be set once and do not need to be changed subsequently.  

1) A focusing knob is usually provided in the center which focusses both sides at the same time, to focus the binoculars on objects of varying distances.

1) A focusing knob is usually provided in the center which focuses both sides at the same time, to focus the binoculars on objects of varying distances.

2) The distance between the eyes (the ''intraocular distance'') varies from person to person. In order to allow the distance between the binocular tubes to be changed, they are hinged together at the center. Often there is a graduated scale at the hinge from which the intraocular distance can be read, usually in millimeters. If a user remembers their intraocular distance, they can quickly bring any pair of binoculars back to setting that is proper for them.

2) The distance between the eyes (the ''intraocular distance'') varies from person to person. In order to allow the distance between the binocular tubes to be changed, they are hinged together at the center. Often there is a graduated scale at the hinge from which the intraocular distance can be read, usually in millimeters. If a user remembers their intraocular distance, they can quickly bring any pair of binoculars back to setting that is proper for them.

3) A second focussing adjustment is provided, usually on the right eyepiece, usually with a scale and markings in diopters. For many people, this adjustment should be set to the zero mark. Some people will find that because of refractive differences in their eyes, when the left binocular is perfectly focussed, the right binocular will be slightly out of focus. It can be brought into focus by adjusting the right eyepiece focus. Once the right eyepiece focus is set correctly, it will be correct at all distances and does not need to be adjusted again.  

3) A second focusing adjustment is provided, usually on the right eyepiece, usually with a scale and markings in diopters. For many people, this adjustment should be set to the zero mark. Some people will find that because of refractive differences in their eyes, when the left binocular is perfectly focussed, the right binocular will be slightly out of focus. It can be brought into focus by adjusting the right eyepiece focus. Once the right eyepiece focus is set correctly, it will be correct at all distances and does not need to be adjusted again.  

==Designs==

==Designs==

The pupil of the eye varies in size depending on how bright the light is. At night, the dark-adapted eye expands to about 7 mm. In room light or shady daylight, it is about 3-4 mm. In very bright daylight it may be less than 2 mm.  

The pupil of the eye varies in size depending on how bright the light is. At night, the dark-adapted eye expands to about 7 mm. In room light or shady daylight, it is about 3-4 mm. In very bright daylight it may be less than 2 mm.  

What this means is that, in the examples above, night, the 7x50 "night glasses" will give a much brighter image than the other two. Under ordinary conditions, the 7x50 will not be any brighter than the 7x35s (and are considerably heavier and more expensive). And in bright daylight, there may not be any meaningful differences in brightness between the three (and if the 8x20s are slightly dimmer, that may be a good tradeoff in return for their compactness and light weight).

What this means is that, in the examples above, night, the 7x50 "night glasses" will give a much brighter image than the other two. Under ordinary conditions, the 7x50 will not be any brighter than the 7x35s (and are considerably heavier and more expensive). And in bright daylight, there may not be any meaningful differences in brightness between the three (and if the 8x20s are slightly dimmer, that may be a good trade-off in return for their compactness and light weight).

[[Category:Technology]]

[[Category:Technology]]