Comments on: How long can i see in Binoculars of 60X35? http://www.binocularsguide.net/how-long-can-i-see-in-binoculars-of-60x35/ Giving you the insight you need Mon, 11 Feb 2008 09:45:10 +0000 http://wordpress.org/?v=2.8.4 hourly 1 By: Jaylon Boyd http://www.binocularsguide.net/how-long-can-i-see-in-binoculars-of-60x35/comment-page-1/#comment-44 Jaylon Boyd Sat, 10 Nov 2007 16:26:57 +0000 http://192.168.1.2/?p=71#comment-44 I'm afraid much of David A's answer is incorrect. The 60 number is the magnification. it makes the image seem 60 times bigger, not nearer. The second number is the the entrance pupil diameter, effectively the diameter in mm of the front lens. To see as clearly as possible at night one needs to ensure that the eye is collecting as much light as possible. The pupil diameter of the eye is usually considered to be about 8mm (for instrument design). To find this in a telescope divide the second number by the first. In your example 35 / 60 = 0.6. This value needs to be as large as possible. In this example the area of your eye pupil divided by the exit pupil of the telescope is the square of (0.6/8) = 0.006. Hence compared to the naked eye you can expect the scene to be only 0.6% as bright as seen by the unaided eye. This may seem disastrous. However, what it tells you is that you cannot have such a large magnification for terrestrial binoculars. A more sensible specification would be 8 x 60. or 10 x 75. These magnification and pupil sizes will give little loss of brightness. I’m afraid much of David A’s answer is incorrect. The 60 number is the magnification. it makes the image seem 60 times bigger, not nearer. The second number is the the entrance pupil diameter, effectively the diameter in mm of the front lens.

To see as clearly as possible at night one needs to ensure that the eye is collecting as much light as possible. The pupil diameter of the eye is usually considered to be about 8mm (for instrument design). To find this in a telescope divide the second number by the first. In your example 35 / 60 = 0.6.

This value needs to be as large as possible. In this example the area of your eye pupil divided by the exit pupil of the telescope is the square of (0.6/8) = 0.006. Hence compared to the naked eye you can expect the scene to be only 0.6% as bright as seen by the unaided eye.

This may seem disastrous. However, what it tells you is that you cannot have such a large magnification for terrestrial binoculars. A more sensible specification would be 8 x 60. or 10 x 75. These magnification and pupil sizes will give little loss of brightness.

]]> By: Kelsey Mcbride http://www.binocularsguide.net/how-long-can-i-see-in-binoculars-of-60x35/comment-page-1/#comment-43 Kelsey Mcbride Sat, 10 Nov 2007 14:26:21 +0000 http://192.168.1.2/?p=71#comment-43 In case you don't know, let me explain the meaning of the numbers. The first number is the magnification. In your example you used 60, in this case things would look 60 times closer. An object 60 feet away would appear as 1 foot away. The last number is the size of the objective lense. In your example 35, which would be 35 mm across. The larger the objective lense the more light it can collect. 12x is generally considered the max power that can be hand held [no tri pod] and that is hard for most people to hold steady enough to obtain a sharp image. Next comes the quality of the binoculars. All binoculars are far from being equal even though they may have the same power and objective lense size. A real good set of 12 x 50 night vison binoculars start out at around $800. and up. In case you don’t know, let me explain the meaning of the numbers. The first number is the magnification. In your example you used 60, in this case things would look 60 times closer. An object 60 feet away would appear as 1 foot away. The last number is the size of the objective lense. In your example 35, which would be 35 mm across. The larger the objective lense the more light it can collect. 12x is generally considered the max power that can be hand held [no tri pod] and that is hard for most people to hold steady enough to obtain a sharp image. Next comes the quality of the binoculars. All binoculars are far from being equal even though they may have the same power and objective lense size. A real good set of 12 x 50 night vison binoculars start out at around $800. and up.

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