black crow
Well-known member
136m at 1000m
How does one convert that to ft. at 1000 yds?
How does one convert that to ft. at 1000 yds?
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quick math question. (7 Viewers)
- Thread starter black crow
- Start date
Theo98
Eurasian Goldfinch
black crow
Well-known member
Now we have two answers. The first comes to 446 ft and your's to 408.
See why I'm asking?
GPO bino specs.
GENERAL
Magnification Factor
8x
Objective Size
32.0 mm
Exit Pupil
4.0 mm
Eye Relief
16 mm
Close Focus
2.0m
Angular Field of View
Not Available
Linear Field of View
136m at 1000m
If this is 446 ft. I'm interested. If it's 408 ft. not so much.
See why I'm asking?
GPO bino specs.
GENERAL
Magnification Factor
8x
Objective Size
32.0 mm
Exit Pupil
4.0 mm
Eye Relief
16 mm
Close Focus
2.0m
Angular Field of View
Not Available
Linear Field of View
136m at 1000m
If this is 446 ft. I'm interested. If it's 408 ft. not so much.
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Theo98
Eurasian Goldfinch
John,
446 ft FOV is correct, for 1000 meters! However 1000 meters = 1094 yards!! [446ft@1094yds IS 408ft@1000yds] !!!
If you want to state the FOV in yards, you have to multiply the 446 by .9144 factor (1 yard= .9144 meter).
When wanting to covert as you asked, the quickest and easiest way is to just multiply the FOV meters statement by 3, and you will have an accurate FOV conversion in feet!
In reverse, to convert 408ft @ 1000yds, divide 408 by 3 = 136 M @ 1000 Meters!
Confusing, yes! :-C
HERE's a tool that might help in the CC (conversion confusion)?! With the on-set of my CRS, little cheating tools like that help me a lot!! :t:
Ted
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black crow
Well-known member
OK I think I got it. Thanks for your help guys.
Theo98
Eurasian Goldfinch
Made in Germany and the bigger glass has gotten great reviews...these 8X32s do appear interesting! Nothing wrong w\408ft FOV if they're into 80-90% sweet spot!!
Ted
The issue here is a bit of mystery to me. Not whether it is one or the other, but why so many people get confused by it. Hope the following works for you if your reasoning has been tripped (and does not confuse further!) As the distance increases from the user the field of view spreads with its limits along a V shape with straight-line boundaries. The ratio of [distance] to [width across at that distance] remains constant (at any distance). If at 1000 m it is 136 m then at 1000 yards it is 136 yards. (That is 136x3 ft at 1000 yards, or 408 ft at 1000 yards.)
black crow
Well-known member
It is confusing as sometimes it's listed as 136 ft at 1000m. It makes me nuts sometimes. Look at my meopro. On the website it says FOV 384 ft. A 10x at 384 ft fov give me a break. That's not correct at all. It's something like 354 ft.
This is on the Meopro website and also at Sports Optics but it's wrong. Where are they getting their numbers?
Meopta MeoPro 10x32 HD
Meopta Specifications Quick Review
binocular magnification: 10X
binocular weight: 21.09 ounces
field of view: 384 feet @ 1000 yards
I found this at BH Photo Field of View 351.7' @ 1000 yd / 117.2 m @ 1000 m This is correct. How can the Meopta website get it wrong?
This is on the Meopro website and also at Sports Optics but it's wrong. Where are they getting their numbers?
Meopta MeoPro 10x32 HD
Meopta Specifications Quick Review
binocular magnification: 10X
binocular weight: 21.09 ounces
field of view: 384 feet @ 1000 yards
I found this at BH Photo Field of View 351.7' @ 1000 yd / 117.2 m @ 1000 m This is correct. How can the Meopta website get it wrong?
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Leica had some strange figures for FoV when they put out the Ultravid HD-Plus 32 series, I emailed them, and they quickly corrected the errors. So this is not unheard of. Leica, Meopta, bah! Black crow, ignore these dilettantes, we know better.
PS. In such a situation as you describe it can be difficult or impossible to get at the correct figure. One can look at the manufr.'s figures for the FoV in degrees and convert from that, or for the meters/yards figure again in the manufr.'s text (as against their specs list). This may yield a different result, and you then have to reckon which is more correct! Or search though the internet for reviews which may have their own estimates. Emailing the manufr. does not always work for a tech. query, as it might be answered by a non-tech. person and then the answer is sometimes incorrect.
PS. In such a situation as you describe it can be difficult or impossible to get at the correct figure. One can look at the manufr.'s figures for the FoV in degrees and convert from that, or for the meters/yards figure again in the manufr.'s text (as against their specs list). This may yield a different result, and you then have to reckon which is more correct! Or search though the internet for reviews which may have their own estimates. Emailing the manufr. does not always work for a tech. query, as it might be answered by a non-tech. person and then the answer is sometimes incorrect.
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black crow
Well-known member
Well thanks. I think I understand better at least. Now I have to sleep. My head hurts. lol
Gents
It helps even more if you treat the fov figures of feet at 1,000 feet and metres at 1,000 metres as the diameter of the circle of view you see through the binos. Calculate the area of this circle use the formula pi multiplied by radius squared and you find that those extra few feet or metres that don't look too important can mean a significant difference when calculating the actual area of sky, hill, lake, shore or marsh that you can capture through your binos.
And if you calculate the area of view for two binos and find that one of them has an area 20% bigger, it is good to know that this percentage advantage remains the same no matter what the viewing distance.
Lee
It helps even more if you treat the fov figures of feet at 1,000 feet and metres at 1,000 metres as the diameter of the circle of view you see through the binos. Calculate the area of this circle use the formula pi multiplied by radius squared and you find that those extra few feet or metres that don't look too important can mean a significant difference when calculating the actual area of sky, hill, lake, shore or marsh that you can capture through your binos.
And if you calculate the area of view for two binos and find that one of them has an area 20% bigger, it is good to know that this percentage advantage remains the same no matter what the viewing distance.
Lee
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Lee,
Because Pi is constant you only need to compare the radius (or diameter) squared. I can never remember past the third decimal place for Pi anyway.
I find this link useful for converting linear distances into angles, and vice versa.
http://www.1728.org/angsize.htm
It's good for other things as well, like maximum AFoV from the ER and eye lens diameter, visual acuity, optical resolution and other stuff.
David
Because Pi is constant you only need to compare the radius (or diameter) squared. I can never remember past the third decimal place for Pi anyway.
I find this link useful for converting linear distances into angles, and vice versa.
http://www.1728.org/angsize.htm
It's good for other things as well, like maximum AFoV from the ER and eye lens diameter, visual acuity, optical resolution and other stuff.
David
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black crow
Well-known member
Never learned much math. My childhood was too chaotic to be able to pay attention to much at school. I do not remember how I passed any math class but I must have somehow. I can add and subtract, divide and multiply but that's about where it ends. It's amazing with the life I've had how little more than that I've needed, UNTIL NOW.:-C Fortunately I have you guys because for me Pi is something to eat:t:
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Lee,
Because Pi is constant you only need to compare the radius (or diameter) squared. I can never remember past the third decimal place for Pi anyway.
I find this link useful for converting linear distances into angles, and vice versa.
http://www.1728.org/angsize.htm
It's good for other things as well, like maximum AFoV from the ER and eye lens diameter, visual acuity, optical resolution and other stuff.
David
Thanks David and thanks also for the link. Looks great.
Lee
jape
Well-known member
um, autism for me means maths is ugg. i think lee and david are saying the actual view size being a circle not just a line is a fair bit bigger with more fov, more than just the few feet expressed as a line might show. and you can show that by multiplying more bits. unfortubarely when it comes to pirsquared ( my keyboard doesnt have the symbols) i dont know whether you do the r2 bit then pi or pi r then sqyare. or if that makes a difference. and david lost me when he put (or diameter) because one is twice the other.
so if fov is bigger in one bin of same type (mag and app) then the circle will be bigger. as long as they use same units of measurement? and then we have to worry about edge focus? sigh. i am going to buy bill's unmentionable book and see what he has to say,!!
so if fov is bigger in one bin of same type (mag and app) then the circle will be bigger. as long as they use same units of measurement? and then we have to worry about edge focus? sigh. i am going to buy bill's unmentionable book and see what he has to say,!!
Jape,
If you had two binoculars, one with a 120m@1000m and the other a 140m@1000m view, you could say that the second had a 16.7% larger view. It you calculate the area by pi x r squared it would be 11310m2 vs. 15394m2. That is 36% bigger. If you just calculate r squared instead it is 3600 vs. 4900 or again 36% bigger. If you do diameter squared it is 14400 vs. 19600 which is again 36% bigger. Just simplifying the maths to show that area is more persuasive than the linear dimension.
Hope that helps.
David
If you had two binoculars, one with a 120m@1000m and the other a 140m@1000m view, you could say that the second had a 16.7% larger view. It you calculate the area by pi x r squared it would be 11310m2 vs. 15394m2. That is 36% bigger. If you just calculate r squared instead it is 3600 vs. 4900 or again 36% bigger. If you do diameter squared it is 14400 vs. 19600 which is again 36% bigger. Just simplifying the maths to show that area is more persuasive than the linear dimension.
Hope that helps.
David
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