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How do YOU calculate FoV?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2010 at 06:59
tpcollins View Drop Down
Optics Journeyman
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I'd ordered both a Leupold 8x32 non-HD Gold Ring and a Zen Ray 7x36 EDII with the intention of keeping one and returning the other - the Leupold won. Among the several issues with the Zen, it's listed 477' FoV seemed less than the 420' listed for both the Leupold and my Zeiss Victory binocs. I had been setting them on a step ladder shelf and was looking at the school behind my house so I could get a good comparison with a stable view. The rep from Zen Ray said my comparison should only be made when looking thru one barrel because different binocular have different "overlaps". I rechecked them  again and when looking thru just one barrel, the Zen did have a larger FoV.

But I would think most people use both barrels. And if the FoV is wider using both, that's all I'm interested - mine must have good "overlap". Just wondering if this is how everyone calculates their FoV? Thanks.   
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2010 at 09:01
Hitthespot View Drop Down
Optics GrassHopper
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I didn't know that?  I thought field of view was calculated using both barrels.  Who cares what it is when looking through one.    However on the other side of that, I guess it could never be less than what one barrel is.
 
Bill
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2010 at 17:36
Klamath View Drop Down
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Just set up a measuring tape taped or tacked to a wall.  Place the oculars a precisely measured distance, say 10 meters or 30 feet (10 yards).  Use a tripod and then satisfy yourself by using both barrels together or single and see how much measurement is visible on the tape, edge to edge.  The 10 yards to 1000 yards conversion is pretty simple math.  The close in measurement is probably not as precise as compared to other methods, but it is usually pretty close.
 
While I like the Gold Ring 8x32, and would use one without reservation, there is no way my eyes tell me that the field of the Gold Ring is bigger than the ZEN.  However, you may be one of those folks who is sensitive to apparent field of view aka AFOV.  The old standard to compute the AFOV is angular FOV degrees (8* in the case of the Gold Ring) x the magnification of the binocular.  In the case of the Gold Ring we get an AFOV of 8x8=64* AFOV.  In the case of the 9* FOV of the 7x36 ZEN ED we get an AFOV of 9x7=63* AFOV, which is a degree less than the GR.  However I personally doubt many will tell the difference.
 
Another thing is the reaction of different eyes to different magnifications.  You may well be one who simply has eyes better suited to 8x, whereas I really can't tell much to no difference between 7x and 8x.  This same effect is likely why some people swear by their 10x.  When I look at each of the two binoculars, it is pretty easy for me to tell the ZEN is biting off a bit more territory than the GR.  I also tend to think that fov makes less difference when we get over 7* and we get to the max usable for most at 9*.  From there individual perceptions of various factors such as edge sharpness or several others will basically tell the user what their eyes like best.
 
Also as an aside, I have had many ZEN ED binoculars in hand.  My current go to glass is my ZEN 7x36.  None of them have exhibited the focus wheel characteristics you have described. 


Edited by Klamath - July/09/2010 at 17:41
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/10/2010 at 10:42
tpcollins View Drop Down
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Thanks Klamath, but when I thought I could see a larger FoV with the Leupold, I took them, the Zens, and my Zeiss Victorys out to where I hunt and parked at the end of a field where I could view a fence row about 200 yards away. My Zeiss and Leupold  were both listed at 420', and to me they appeared to have the same identical width when looing at the fence row.
 
The Zen's 477' definately did not cover the same amount of width of fence row to me. I was parked parallel so I could use my window to steady all of the binocs. Like I said in a previous post, the only pro I found with this Zen was they did have a tiny bit more "pop" in the middle of the view over the Leupolds, but nowhere near the pop of my Victorys.
 
When they get back to Portland, I'll contact Charles at Zen Ray to see if he sees the same issues or if it was just a me thing. Either way they were just too long for me to consider as a mid-size binoc - also probably a me thing.
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