Field of view data

[nuttingd]

I notice that some manufacturers list the FOV as ft @ 1000yds and others list it as degrees @ 1000 meters. Can anyone tell me how to convert these?

[Tero]

Umm, if they give FOV in degrees, you can get 5 degrees to 5x52=260ft roughly . 52 to 53. There is a formula for everything. See optics planet, some bins have data in both figures.

here is a random example

105 m/1.000 m 6°/315 ft./1000 yds. 6°
so you divide the ft FIGURE with 3 to get the meters FIGURE

also 91 m / 1000 m=5,2°

[kmiernik]

I notice that some manufacturers list the FOV as ft @ 1000yds and others list it as degrees @ 1000 meters. Can anyone tell me how to convert these?

This is a mistake. FOV is an angle so you can measure it in degrees (not degrees @ 1000m !).

FOV appears in three ways:
1) "x" ft @ 1000 yds
2) "y" m @ 1000 m
3) "z" degrees

Here are mathematical forumulas. I hope you will find them clear enough. This is just simple "school" trigonometry.

To translate 3) to 2):
y = tan(z)*1000 (result in meters)
example: for 6 degrees you get y = tan(6 deg)*1000 = 105 [m]
FOV = 105m @ 1000m

To translate 3) to 1) :
y = tan(z)*1000*3 (result in feets)
example: for 7 degrees you get y = tan(7 deg)*1000*3 = 368 [ft]
FOV = 368ft @ 1000yds

To translate 1) to 3):
z = arctan(x/3000)
example: for 262ft@1000yds you get z = arctan(262/3000) = 5 [deg]

To translate 2) to 3):
z = arctan( y/1000 )
example: for 140m@1000m you get z = arctan(140/1000) = 8 [deg]

And to translate 2) to 1):
x = y*3

And here is a link to table of conversion (at the bottom of the page). I'm afraid it is in Polish only but hope you will find out what is what.

http://www.optyczne.pl/index.php?slownik=63

First column gives you degrees, second meters at 1000 m, third feets at 1000 yds.

[Tero]

Would be most useful to just calculate 4-7 degrees in 0.5 degree increments and print it out and keep it handy.

[nuttingd]

This is a mistake. FOV is an angle so you can measure it in degrees (not degrees @ 1000m !).

FOV appears in three ways:
1) "x" ft @ 1000 yds
2) "y" m @ 1000 m
3) "z" degrees

Here are mathematical forumulas. I hope you will find them clear enough. This is just simple "school" trigonometry.

To translate 3) to 2):
y = tan(z)*1000 (result in meters)
example: for 6 degrees you get y = tan(6 deg)*1000 = 105 [m]
FOV = 105m @ 1000m

To translate 3) to 1) :
y = tan(z)*1000*3 (result in feets)
example: for 7 degrees you get y = tan(7 deg)*1000*3 = 368 [ft]
FOV = 368ft @ 1000yds

To translate 1) to 3):
z = arctan(x/3000)
example: for 262ft@1000yds you get z = arctan(262/3000) = 5 [deg]

To translate 2) to 3):
z = arctan( y/1000 )
example: for 140m@1000m you get z = arctan(140/1000) = 8 [deg]

And to translate 2) to 1):
x = y*3

And here is a link to table of conversion (at the bottom of the page). I'm afraid it is in Polish only but hope you will find out what is what.

http://www.optyczne.pl/index.php?slownik=63

First column gives you degrees, second meters at 1000 m, third feets at 1000 yds.


Great!! Thanks for the info!

[kmiernik]

Would be most useful to just calculate 4-7 degrees in 0.5 degree increments and print it out and keep it handy.

And that's exactly what you can find in link I gave (more precisely from 0.5 to 9.5 with step 0.5 deg). You copy it and change columns explanations to english.

[Tero]

sorry, did not scroll down far enough

[ceasar]

I notice that some manufacturers list the FOV as ft @ 1000yds and others list it as degrees @ 1000 meters. Can anyone tell me how to convert these?

No need to make things more difficult than necessary! If your binoculars use degrees @ 1000 meters simply change the meters to yards (1000 meters becomes 1000 yards.) Now multiply the number of degrees given by 52.5 feet. (6.5 degrees x 52.5 feet for instance.) That will give you a close enough approximation of the FOV in feet at 1000 yards. Since you live in the USA where the Metric system is universally and justly reviled, that is all you need to know.

After all, we bailed Europe out of 2 World Wars using machinery made to these ancient specifications.

Drink a pint to the foot, inch, mile, quart, gallon, link, chain, rod, acre and so on!
B (:

Bob

[Tero]

I never memorized any of this stuff about feet and miles and bigger units. I measure feet up to 20, miles on my bike and degrees F for hot. For temperatures under freezing I use only Celsius. When I was in grade school, -20C was when you got to stay inside for recess.

back to FOV, see
http://en.wikipedia.org/wiki/Field_of_view