What FOV is considered a WIDE FOV? (1 Viewer)

[brocknroller]

A while ago, we had a thread on EWA bins, and someone (it could have been me) asked where does WF stop and EWA begin, but here I ask where does WF begin?

Is there any industry-wide standard? Doesn't seem to be since the term is bandied about rather indiscriminately by manufacturers.

For example, Leica advertises its new Trinnies as being WIDE field. The 10x42 is 6.2*, certainly a respectable FOV for its configuration, 1/10 a degree less than the 8x42 Monarch 5, however, my Celestron 10x50 Nova has 8* FOV. Now that's wide angle. Or is it EWA?

Here's what the reviewer @ binocularsreview dot com said in his rather scant review of the new Trinnies:

"Wide Field of View
The 10×42 model has an impressive field of view of 326ft at 1000 yards (6.2°), but it is the 8×42 model that is most impressive with a FOV of 378ft at 1000 yards (7.2°) which means it easily makes it onto my list of wide angled binoculars and will therefore really appeal to serious birders."

http://www.bestbinocularsreviews.com/blog/new-leica-trinovid-8x42-and-10x42-binoculars-01/

Huh? Makes on his list of wide angled binoculars? "Respectable" or "moderately wide," perhaps, but wide angle @ 7.2* for an 8x42? Does that sound right?

To be clear, I'm not questioning Leica's decision to make the 8x42 Trinnie with 7.2* FOV. The Ultravid is only 2/10 of a degree wide @ 7.4*.

Considering the price point of the Trinnies, it was probably a sensible decision since a moderately wide field limits aberrations and distortions.

Similarly, the 11,5' close focus was also reasonable, although the reviewer had this to say about that, which harkens back to Holger's comments on the Pincushion and Globe Effect thread:

"One feature were these binoculars do not really excel is their fairly distant minimum focusing distance of 11.5ft (i consider anything under 6ft to be excellent) – so possibly not the ideal binoculars if viewing objects close up (like butterflies) is your main intended use for them."

No, not ideal for butterflies, perhaps, but acceptable for birding.

Anyway, not to go off on a tangent with close focus, which could be a subject for another thread, but back to the original question:

How many degrees constitutes a WIDE FOV in various configurations? 8x42? 10x42? 8x32? 10x32?

<B>

 

[ceasar]

I'll go first. This is "feet" @ 1000yds. Who needs degrees for this? This ain't higher math!:smoke:

8 x 42-390'
10 x 42-345'
8 x 32-420'
10 x 32-340'

Bob

 

[NDhunter]

I'll go first. This is "feet" @ 1000yds. Who needs degrees for this? This ain't higher math!:smoke:

8 x 42-390'
10 x 42-345'
8 x 32-420'
10 x 32-340'

Bob

Bob:

Nice work, but please add the degrees, it is often found on the binocular
itself, and I find it easier to compare. Also many here use metric, these
numbers are in feet.

Jerry

 

[NDhunter]

Brock:

Good topic to bring up. It also brings in what is considered a comfortable FOV.

The Allbinos reviewers will say that for the 8x42 size,
they like to see an angle of view of 6.9 - 7.0 degrees to offer a comfortable viewing
experience. They downgrade those with a smaller view, and may call them tunnellike,
or a keyhole view.

Just to throw out a number, 10x42 would be in the range of 6.3 and wider.

The reference standard Nikon 8x32 SE has a very well corrected angle of view of 7.5 deg.

Jerry

 

[ceasar]

Bob:

Nice work, but please add the degrees, it is often found on the binocular
itself, and I find it easier to compare. Also many here use metric, these
numbers are in feet.

Jerry

Binocular manufacturers do this to confuse people. That's because they are made in the metric part of the world but sold in great bunches in the feet and inches part of the world. Same as televisions, refrigerators and assorted other stuff, like Peanut Butter which still comes in ounces.

If we all must march to the same drummer why does everybody want a different binocular?

And to illustrate, I have changed my mind on the 8 x 32 FOV. It should be 393 feet @ 1000 yards. That helps to distinguish it from the 8 x 42 @ 390 feet @ 1000 yards. That's tough to do in degrees and tedious in meters.

Bob

 

[NDhunter]

Binocular manufacturers do this to confuse people. That's because they are made in the metric part of the world but sold in great bunches in the feet and inches part of the world. Same as televisions, refrigerators and assorted other stuff, like Peanut Butter which still comes in ounces.

If we all must march to the same drummer why does everybody want a different binocular?

And to illustrate I have changed my mind on the 8 x 32 FOV. It should be 393 feet @ 1000 yards. That helps to distinguish it from the 8 x 42 @ 390 feet @ 1000 yards. That's tough to do in degrees and tedious in meters.

Bob

Bob:

Go grab a pair of your favorite binoculars. It is often on the focuser or badge.
The FOV is probably stated with an angle, I have not been able to find it stated in ft./1000.

The degrees of angle is the way the field of view is commonly described.

Your example of comparing ft. to metric, is exactly why degrees are used.

Jerry

 

[Kammerdiner]

I'll go first. This is "feet" @ 1000yds. Who needs degrees for this? This ain't higher math!:smoke:

8 x 42-390'
10 x 42-345'
8 x 32-420'
10 x 32-340'

Bob

Bob, I'd say that pretty much nails it, except I'd bump the 8x42 up to 420.' The 8x32 is the next to bump up. Vortex 32mm has something like 477': nope, I doubt they can pull that off. But Swaro has 426' with the 32mm SV and 440' is surely within reach.

Incidentally, at least for my money, these figures are mostly at the upper limits of what I need. Wider still and, well, I guess I just don't care. Birds ain't that close and they ain't that big.

Mark

 

[David Swain]

I have changed my mind on the 8 x 32 FOV. It should be 393 feet @ 1000 yards.

Which happen to be the specs on the 8x32SE, which claims 7.5*. Once upon a time, porros had all those flat housing plates on which all this could be printed; now it gets squeezed, sometimes, onto the end cap of focus wheels on roofs.

David

 

[FrankD]

Easy one Brock. If we go by astro eyepiece standards then, regardless of magnification, a wide field of view is 60 degrees of apparent field of view but less than 70. Greater than 70 degrees apparent would be extra wide field and greater than 80 would be super wide field.

 

[Chosun Juan]

Brock,

The calculations between metric and imperial are pretty straight forward: FOV (ft@1,000yds) = 3xFOV (m@1000m)

However, as Frank said it is easiest to refer to in terms of AFOV (I think Frank used conventional (imperial)? (ie. AFOV = real fov (in degrees) x magnification)

According to ISO 14132-2:2002 (conventional, I think) an AFOV over 60* is considered wide.

For an 8x this equates to 7.5* RFOV = 131.7m @1km = 395ft @1,000yds. Shazzam! pretty much the Nikon 8x32SE .....

When calculated according to ISO 14132-1:2002 (below graphic is the easiest explanation), this corresponds to ~55*.

The Zen-Ray 8x43 ED3 rfov is 8.1*, or 426ft @1,000yds = 142m @1km =>64.8* afov, conventional = 59* ISO 14132-1:2002
The Zen-Ray PrimeHD's about that same AFOV, but flatter. I'd don't think I'd want to go to an AFOV any less than that ~65*



If you consider extra wide, 70* conventional corresponds to ISO ~63*.

For example in an 8x bin, ISO 63* AFOV
1/2(RFOV) = arctan{tan[1/2(AFOV)]/mag}
1/2(RFOV) = arctan{tan[31.5]/8}
1/2(RFOV) = 4.38
or 8.76* real => 154m @1km ~462ft @1,000yds)

Shazzam! a Nikon 8x30 EII, Not many! (any?) bins make this grade and retain a flat field


Chosun :gh:

 

[ceasar]

Bob, I'd say that pretty much nails it, except I'd bump the 8x42 up to 420.' The 8x32 is the next to bump up. Vortex 32mm has something like 477': nope, I doubt they can pull that off. But Swaro has 426' with the 32mm SV and 440' is surely within reach.

Incidentally, at least for my money, these figures are mostly at the upper limits of what I need. Wider still and, well, I guess I just don't care. Birds ain't that close and they ain't that big.

Mark

I was trying to keep it within Brock's parameters of WA as opposed to EWA and where WA should start. Which is primarily why I limited my comments to FOV @ 1000 yards rather than degrees. It gives me a mental picture of the view. I have specific places with landmarks near my home where I compare binoculars fields of view. It is a simple form of triangulation from where I am to where they are. These landmarks have distances to them and between them which do not change. I don't know these distances accurately but I can see the differences in the FOVs of different binoculars by looking at the landmarks.

I can't come up with a mental picture of a binocular's FOV without converting 7.5* to feet @ 1000 yards if only roughly. I could do the same thing with meters but why in the hell should I? I am no better off. Some people are happy to think metrically. Some were taught to think that way. I was not and many still are not. My son who will soon have a PhD in Physics can do both with ease. He just shrugs his shoulders and moves on.

Bob

 

[ceasar]

Bob:

Go grab a pair of your favorite binoculars. It is often on the focuser or badge.
The FOV is probably stated with an angle, I have not been able to find it stated in ft./1000.

The degrees of angle is the way the field of view is commonly described.

Your example of comparing ft. to metric, is exactly why degrees are used.

Jerry

Jerry,

I responded to this in my response to Mark above and it gives my point of view on how I see a Field of View in my minds eye. I will grant that I was being facetious in my first comments and probably should have been more diplomatic.

Bob

 

[ceasar]

Which happen to be the specs on the 8x32SE, which claims 7.5*. Once upon a time, porros had all those flat housing plates on which all this could be printed; now it gets squeezed, sometimes, onto the end cap of focus wheels on roofs.

David

I was specifically thinking of the 8 x 32 SE when I changed my mind. It has always been a "reference standard." I have one. It's FOV is about 70' smaller than the Nikon 8 x 32 EII at 1000 yards; an EWA binocular.

Bob

 

[Nixterdemus]

It would seem that conventional BF wisdom suggests the best Minox bins as
on the cusp of wide angle.

 

[idaho john]

I'll go first. This is "feet" @ 1000yds. Who needs degrees for this? This ain't higher math!:smoke:

8 x 42-390'
10 x 42-345'
8 x 32-420'
10 x 32-340'

Bob

Thank you Bob. I appreciate the transfer into mathematical concepts that I actually understand.

John

 

[Simon Wates]

And to illustrate, I have changed my mind on the 8 x 32 FOV. It should be 393 feet @ 1000 yards. That helps to distinguish it from the 8 x 42 @ 390 feet @ 1000 yards. That's tough to do in degrees and tedious in meters.

Bob

I apologise but thank God we don't have to convert from metric to feet and inches - must cost a fortune to use these barmy measurements - after all 12 inches to a foot! - it amazes me that this system has persisted so long.

Metric is beautiful and makes much more sense surely - look:

10x10x10cm = 1 litre, which using water weighs 1 kilo - simply beautiful!

 

[JabaliHunter]

It gets even more fun when you start to consider decimal fractions of imperial units! e.g. tenths of a foot (e.g. 10.3 ft) or thousands of an inch (e.g. 0.002 in)
Whose clever idea was that?

 

[Troubador]

I apologise but thank God we don't have to convert from metric to feet and inches - must cost a fortune to use these barmy measurements - after all 12 inches to a foot! - it amazes me that this system has persisted so long.

Metric is beautiful and makes much more sense surely - look:

10x10x10cm = 1 litre, which using water weighs 1 kilo - simply beautiful!

The systems based on 12 (inches in 1ft, pennies in a shilling) was thought pretty useful because 12 can be divided by 2, 3, 4, and 6 (i.e. broken down into fractions) and still come up with whole number answers.

Metric is beautiful but imperial was not without its beauties too.

Lee

 

[mak]

WFOV = >60 degrees.

I use this calculation.

Example: 8x42 = 135m @ 1000m = 135 / 17.45 x mag (8) = 61.89 degrees (rounded 62 degrees).

When being trained this was the simple equation given to me. Easy for us in the UK as our old vat rate was 17.5 (you can use this as well).

mak

 

[Torview]

I apologise but thank God we don't have to convert from metric to feet and inches - must cost a fortune to use these barmy measurements - after all 12 inches to a foot! - it amazes me that this system has persisted so long.

Metric is beautiful and makes much more sense surely - look:

10x10x10cm = 1 litre, which using water weighs 1 kilo - simply beautiful!

As an avid weather observer of 12+ years I agree, metric every time.

1mm rain = 1 litre of water per sq meter, try working out 1/25th inch in pints per sq yard !

Back on topic I find quoted fov pretty useless, some bins with a wfov quoted have felt hemmed in, whilst others which read narrow have seemed fine.