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FOV 8x vs. 10x

Printed From: OpticsTalk by SWFA, Inc.
Category: Other Optics
Forum Name: Binoculars
Forum Description: Anything that requires two eyes to look through it
URL: http://www.opticstalk.com/forum_posts.asp?TID=44161
Printed Date: October/22/2017 at 14:13


Topic: FOV 8x vs. 10x
Posted By: Aztex
Subject: FOV 8x vs. 10x
Date Posted: May/26/2017 at 22:00
Hi,

Decided to upgrade binoculars. Ordered pair of NOS Japan made Razor HD 10x42. Meanwhile stumbled upon a NOS Japan made Viper 8x42. Bought both figuring they'd be different enough.

Finally had both side by side and was surprised to find the have an almost exact FOV. 
10x Razors 362' at 1000' 6.9°
8x Vipers 347' at 1000' 6.6°

So I'm confused. I'm looking at a circle that is 10x closer and it 362' diameter and one that is 8x closer 347' diameter...

Usually as power increases FOV gets smaller all things being equal.

Here is actually seems like the 8x are reaching farther... giving greater magnification at anything over 100'

Confused in AZ....

Thanks!

AZtex



Replies:
Posted By: RifleDude
Date Posted: May/26/2017 at 23:55
You are comparing 2 different series of binos, with 2 entirely different optical designs. There are several factors that affect FOV, magnification being just one of them, the others being things like eye relief, internal stops, eyepiece design, etc. The correct comparison would be between 8x and 10x of the same series, where lower power will always have wider FOV.

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Ted


Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle.


Posted By: Aztex
Date Posted: May/27/2017 at 10:14
Thanks,

I understand FOV can vary but how is power figured then?

I mean if I'm looking at a brick wall made of 1' wide bricks 1000' away with my 10x Razors I'll see 362 brick wide circle.

Looking at the same wall I'd see 347 brick wide circle with my 8x Vipers. To me this makes the 8x more "powerful" than the 10x......

Perhaps I need a link to some basics and a bit more about binocular optics.

Oddly I was side by size with 10x Leica, Zeiss, Swarovski and the Razors and they all had what I'd call exact magnification... which they do!

Thanks!

Aztex


Posted By: urbaneruralite
Date Posted: May/27/2017 at 10:56
You're not alone. That confuses me, too. I notice it more in rifle scopes than anything else. 

In practical terms without knowing the behind the scenes math of the designs, I guess the difference in use between the 10x and 8x is not readily apparent until you exceed the reach of the 8x for acuity. Part of the reason I am posting this is that the best and quickest way to get information on the internet is to post something that is incorrect. 


Posted By: RifleDude
Date Posted: May/27/2017 at 13:02
An object viewed through an optic can be both more magnified and have narrower field of view around it simultaneously. Note that optics from different manufacturers and/or different series can have the same magnification and yet different fields of view at the same time. Imagine looking through an optic of a given magnification, then hold a washer up to the eyepiece, stopping down and limiting the field of view you see. The apparent size and amount of detail (magnification) on the object doesn't change, but the field of view did. Rarely does comparable optics from different manufacturers of the same magnification have the exact same FOV, and 8x and 10x are close enough in magnification that the FOV for each could be close or even be the inverse of what you expect when comparing optics of different series.

In general terms, increasing magnification reduces FOV, but that assumes comparing optics of the same design.

-------------
Ted


Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle.


Posted By: Kickboxer
Date Posted: May/27/2017 at 15:05
Some additional info:
http://www.opticstalk.com/field-of-view-actual-magnification_topic12322.html - http://www.opticstalk.com/field-of-view-actual-magnification_topic12322.html


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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: urbaneruralite
Date Posted: May/28/2017 at 19:25
Well, now that comes around to it. The amount of the image that comes out of the ocular taken up by an object decreases with field of view. Then when you put a reticle across it, you have the effect of seemingly lower magnification.

Is this among the reasons why oculars keep getting bigger?


Posted By: Klamath
Date Posted: May/29/2017 at 13:55
The field of view is more or less a function of eye piece design.  Bigger or smaller objectives have not much to do with the fov.  The size of the objective determines (in some limits) the focal length of the instrument.  Wider means longer and vice versa.  The length determines the angle of light entering the eye piece and the eye piece design determines how wide the fov will be.  Scopes with wide fov usually have larger ocular mechanisms.  Objective diameter also determines how much light will be available, more light generally meaning potential higher resolution.  Binoculars with wider fov have wider ocular lenses as a general rule.  Most modern eye pieces give fov angular fov of  5-9 degrees or so.  Widening the fov will reduce eye relief if carried too far.  Increasing magnification will usually require reduced angular field as compared to an lesser magnification.  Taking typical 8x and 10x binoculars you will find that the 8x will mostly fall in the range of 7-8 degrees while 10x will run 6 to 6.5 degrees.  This leads into the concept of apparent field of view.  The simple way for afov calculation is to magnify the angular fov times the angular fov. As a general rule, wide angle binoculars are loosely defined as having an afov of 60* or greater.  With an 8* 8x binocular we find an afov of 64*, with a 6.5* 10x we have a 65* afov,  pretty much equal. 

Until eye piece design advances to improve eye relief on wider fields,  what is out there that is where we will likely stay


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Steve
"Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted". William Bruce Cameron



Posted By: m1911
Date Posted: June/04/2017 at 05:46
AZtex....

You mentioned ordering NOS (new-old-stock) Razor HD Binoculars MADE IN JAPAN....

So I bought the Razor-HD 10x42's six months ago....the eye-piece ring says MADE IN JAPAN.

I like them so I ordered the 12x50 Razor-HD's and received them yesterday.
The eye-piece ring says MADE IN CHINA......

I'm sending them back....it's disappointing that Vortex would use China to source their FLAG-SHIP-Highest-End line of anything.....

I understand the China source for most of their other offerings.....just NOT RAZOR-HD's....

What makes it worse......say you need warranty service in the future and they replace your MADE IN JAPAN's with MADE IN CHINA's....

Sigh....






Posted By: koshkin
Date Posted: June/04/2017 at 09:58
You can make some exceptional binos and spotters in China these days. Did the 12x50 perform poorly in some way?

ILya

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http://www.opticsthoughts.com - www.opticsthoughts.com
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Those who are merciful to the cruel, are cruel to the merciful.


Posted By: m1911
Date Posted: June/04/2017 at 17:34
I "thought" the trend at Vortex was to keep/put their highest end models (AMG & Razors) in Japan or USA.
I totally understand the rest of their offerings being sourced elsewhere....just NOT the highest offerings.

Their Made-in-China 12x50 Binoculars would service me for 10 lifetimes I'm sure.....and I really love the fit-n-finish of the Razor Binoculars and Spotting Scopes.
But I would spend more for Made-in-USA, Japan, or Germany....






Posted By: JGRaider
Date Posted: June/05/2017 at 10:12
Originally posted by koshkin koshkin wrote:

You can make some exceptional binos and spotters in China these days. Did the 12x50 perform poorly in some way?

ILya


Exceptional in what way?  Optics....I agree.  Build quality...not so sure.  


Posted By: supertool73
Date Posted: June/05/2017 at 11:12
Yeah, I would be sending them back too.  I would not spend $1000+ for a pair of Chincom bino's. 


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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."


Posted By: koshkin
Date Posted: June/05/2017 at 12:42
Originally posted by JGRaider JGRaider wrote:

Originally posted by koshkin koshkin wrote:

You can make some exceptional binos and spotters in China these days. Did the 12x50 perform poorly in some way?

ILya


Exceptional in what way?  Optics....I agree.  Build quality...not so sure.  

It all depends on the price.  Some are pretty well built, but they cost accordingly.  Chinese OEMs are trying to move up market with varying degrees of success.

Then there are different ways to deal with the product when it gets here.

For example, Vortex' latest Razor spotter is technically built in China.  They make it there, bring it to the US, go over everything and do some final alignment here in Wisconsin.

I have been beating one up for a bit and it is a really well built spotter.  

A bunch of fairly expensive Zeiss stuff is, best I can tell, made in China (both binoculars and spotters).  They attach eyepieces to the bodies in Germany and avoid labeling them "Made in China" that way.  Honestly, these are really well built products.

In the modern economy, build quality can be achieved in a variety of locations.  In the end it really comes down to how QC is done.  

Now, if you do not want a Chinese product for political or ideological reasons, I am totally fine with that.  However, the build quality argument is not as clear cut as it used to be.

In the interest of full disclosure, my primary binocular is German built Leica Noctivid 8x42 with Japanese built Vortex Viper 6x32 as backup.  My primary rifle optics seem to be made in Canada, US and Japan. Reflex sights hail from England, Germany and China. The spotter I have been using the most lately is Austrian.  I am not trying to justify any of my purchases.  However, some stuff I have seen coming from China recently is legitimately good and, most importantly, there are some price ranges in different market segments that are not well addressed right now, leaving a gap for Chinese OEM to move a little upmarket.  

ILya 


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http://www.opticsthoughts.com - www.opticsthoughts.com
http://www.opticsthoughts.com - opticsthoughts.smugmug.com
Those who are merciful to the cruel, are cruel to the merciful.


Posted By: JGRaider
Date Posted: June/05/2017 at 14:45
Thanks, and you bring up some good points.  It's especially hard to determine where some of the Zeiss and Leica stuff is "made" nowadays.  I do know the Terra binocs are Chinese and you can tell pretty quickly, as with the Vortex Diamondbacks and several other Vortex binos.  


Posted By: koshkin
Date Posted: June/05/2017 at 18:40
European Leica stuff is made either in Germany or in Portugal and they are marked accordingly.  Where exactly their US stuff is made, I do not know, other than in the US somewhere.  I am looking at the 2-10x50 ER5 and it seems to be a pretty decent scope.

I am not aware of any Leica stuff outsourced to Asia in the current product line, but then again, they don't exactly give me a weekly update on that.

With Zeiss, I am pretty certain all the Conquest HD stuff is made in China with eyepieces slapped on in Germany (and those are pretty nice products).  Terra is supposedly made in Japan, but I have serious doubts about that.

With the higher end stuff, I can't tell for sure.  There are a rumors floating around, but enough that I have been able to substantiate, and, honestly, I havn't tried very hard to do that.

As long as they do the QC properly, I do not care where it is made.

ILya


-------------
http://www.opticsthoughts.com - www.opticsthoughts.com
http://www.opticsthoughts.com - opticsthoughts.smugmug.com
Those who are merciful to the cruel, are cruel to the merciful.


Posted By: JGRaider
Date Posted: June/05/2017 at 20:02
Zeiss guy told me the Conquest HD is a Kamakura, Japan made glass, the Terra binocs made in China.  For a while Meopta made their FL T spotters.  


Posted By: koshkin
Date Posted: June/06/2017 at 11:32
For all I know, they may very well be.  Like I said, that is not something I care about deeply, so I have not made a concerted effort to dig down into it.

I know HD5 scopes are made in China from first hand sources.  

ILya


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http://www.opticsthoughts.com - www.opticsthoughts.com
http://www.opticsthoughts.com - opticsthoughts.smugmug.com
Those who are merciful to the cruel, are cruel to the merciful.



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