Binocular Lenses In Groups Question

[refractordude]

Hello There


Can someone please explain the difference in quality of the view based on binocular lenses in groups. Also how do I do the math to determine the field of view in degrees based on the numbers in the FOV image. Thanks to you all.

[Stefan Buda]

Originally Posted by refractordude

Hello There

Also how do I do the math to determine the field of view in degrees based on the numbers in the FOV image. Thanks to you all.

FOV = inv. sin(489/1000) which gives 32.5 degrees.

Edit: I just realized that they used two different units. Just convert one of the units and apply the formula again.

[Buck]

Originally Posted by refractordude

Hello There


Can someone please explain the difference in quality of the view based on binocular lenses in groups. Also how do I do the math to determine the field of view in degrees based on the numbers in the FOV image. Thanks to you all.

The quality of the view is more likely dependant on the type and quality of the glass used in the objective lenses, as well as the manufacturing precision of the prisms and eyepieces. The style and type of glass used in the last two will also have an impact on the quality of the view.
Top of the range binoculars often employ the latest SD glass components as well as superior coatings on all glass to air surfaces (objectives and prisms) to achieve an APO standard. They will also match the eyepieces to achieve the best results as well as use a Field Flattening lens to gain maximum focus across the full field. Most (all) binoculars have a relatively fast focal length/ratio so need the best design and quality components to achieve an all in focus flat field with high light throughput good contrast and free of chromatic aberrations. It's expensive to have all the variables at the peak of performance, and like quality camera lenses, you generally get what you pay for.

Paul

[Bobbyoutback]

Binocular True Field Of View Conversion Tables

[The following spec conversions have been rounded to the nearest tenth of a degree. Actual starfield measurements may vary.]


ft/1000yds

100 = 1.9° TFOV (ft divided by 52.5)
110 = 2.1°
120 = 2.3°
130 = 2.5°
140 = 2.7°
150 = 2.9°
160 = 3.0°
170 = 3.2°
180 = 3.4°
190 = 3.6°
200 = 3.8°
210 = 4.0°
220 = 4.2°
230 = 4.4°
240 = 4.6°
250 = 4.8°
260 = 5.0°
270 = 5.2°
280 = 5.4°
290 = 5.5°
300 = 5.7°
310 = 5.9°
320 = 6.1°
330 = 6.3°
340 = 6.5°
350 = 6.7°
360 = 6.9°
370 = 7.0°
380 = 7.2°
390 = 7.4°
400 = 7.6°
410 = 7.8°
420 = 8.0°
430 = 8.2°
440 = 8.4°
450 = 8.6°
460 = 8.8°
470 = 9.0°
480 = 9.1°
490 = 9.3°
500 = 9.5°
510 = 9.7°
520 = 9.9°
530 = 10.1°
540 = 10.3°
550 = 10.5°
560 = 10.7°
570 = 10.9°
580 = 11.0°
590 = 11.2°
600 = 11.4°


m/1000m

35 = 2.0° TFOV (m divided by 17.5)
38 = 2.2°
41 = 2.4°
44 = 2.5°
47 = 2.7°
50 = 2.9°
53 = 3.0°
56 = 3.2°
59 = 3.4°
62 = 3.5°
65 = 3.7°
68 = 3.9°
71 = 4.0°
74 = 4.2°
77 = 4.4°
80 = 4.6°
83 = 4.7°
86 = 4.9°
89 = 5.1°
92 = 5.3°
95 = 5.4°
98 = 5.6°
101 = 5.8°
104 = 5.9°
107 = 6.1°
110 = 6.3°
113 = 6.5°
116 = 6.6°
119 = 6.8°
122 = 7.0°
125 = 7.1°
128 = 7.3°
131 = 7.5°
134 = 7.7°
137 = 7.8°
140 = 8.0°
143 = 8.2°
146 = 8.4°
149 = 8.5°
152 = 8.7°
155 = 8.9°
158 = 9.0°
161 = 9.2°
164 = 9.4°
167 = 9.5°
170 = 9.7°
173 = 9.9°
176 = 10.1°
179 = 10.2°
182 = 10.4°
185 = 10.6°
188 = 10.7°
191 = 10.9°
194 = 11.1°
197 = 11.2°
200 = 11.4°

[refractordude]

Hello Bobbyoutback


Thanks for the reply. Where do you get the 17.5 and the 52.5?

[Bobbyoutback]

Originally Posted by refractordude

Hello Bobbyoutback


Thanks for the reply. Where do you get the 17.5 and the 52.5?

Thats just the formulas for meters & feet ' EG " if you see 525 FT at a thousand yards it's a nice wide 10deg FOV , most old Japanese binoculars have the information on the back plates .

Have Fun
Bobby

[refractordude]

Hello There


I am interested in the Levenhuk Sherman binoculars. Levenhuk sent me a reply which I snipped. Thanks for all the great help. I am now good on this topic.