Binocular Conundrum: Field of View? - Page 4 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related)
 Not a Member? 


Like Tree1Likes
Reply
 
LinkBack Thread Tools
  #31  
Old 07-03-2013
Cruisingdad's Avatar
Best Looking MALE Mod
 
Join Date: Jul 2006
Location: Washington State
Posts: 9,904
Thanks: 3
Thanked 107 Times in 53 Posts
Rep Power: 10
Cruisingdad is a jewel in the rough Cruisingdad is a jewel in the rough Cruisingdad is a jewel in the rough
Re: Binocular Conundrum: Field of View?

Quote:
Originally Posted by hellosailor View Post
Brian-
I don't mind the move at all, but "kids" has got nothing to do with anything. I posted the opening question in the General Interest / General Discussion area, unless the mouse slipped and dropped it elsewhere?
Although, it should show kids why they don't want to cut class when all those pointy geometry and trig things are being taught. (G) Personally I thought spherical trig was a special form of abuse, until years later when it made a whole lot of sense for celestial nav.
Yep. Somehow it got dropped in the Kids forum. I blame TDW. Not sure why, but he makes a nice target.

Carry on!

Brian
__________________
Sailnet Moderator



1987 Tayana Vancouver 42, Credendo Vides, (Mom and Pops boat, F/T Mobile Live Aboards in Puget Sound)

My Website:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


Follow My Blog at:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


Follow me on Facebook:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #32  
Old 07-03-2013
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,601
Thanks: 2
Thanked 87 Times in 85 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: Binocular Conundrum: Field of View?

Brian-
Well, considering the eight or ten seconds it took while my page moved around and reloaded THREE TIMES just now, thanks to all the crapware from advertisers who need to be housebroken (or horsewhipped, please?)...thanks for the cleanup.

And now back to our main program.

noelex, you totally misread me. I never mentioned the pupil, as in the pupil of the eye, as being a factor in this. What I said was the the EXIT PUPIL of the binocs is all the same, and THAT is stated to be a limiting factor by all the binoc makers. That is, the field of light coming out of the binocs is constrained to a circle 4.2mm in size at the point where is focuses on the retina. (At least, that's how some of them define it.)

Just got off the phone with perhaps the most highly respected brand name of German glass and their answer was "well we use extra-dispersion glass instead of...and..." in other words, they hadn't got a clue as to what FOV even was.

So I fired up the inverse tanget finagler, which says the difference between some of the FOV numbers (like 268/336/375 which seem to represent the spread for 10x42 glasses from multiple sources) correspond to a difference of 5.11d/6.21d/7.32d in terms of the degrees of the actual conve of vision in the binocs. A plus-or-minus one degree change would account for the different FOV, but that also would change the magnification from roughly 9x to 12x as well. Given, again, that the size of the image on the retina is a fixed and limiting factor for all of these.

Now, if they are full of FUD, it is also possible that the narrower FOV glasses will simply present a black ring around the image, rather than filling the retina. That would explain it very simply, allowing for the "exit pupil" to remain the size size, if they are defining "exit pupil" incorrectly and somewhat misleadingly.
Looking at my own 7x50's, which claim a 366 foot FOV, there's a black outer ring, so maybe the ones with the narrower FOV simply have bigger black rings? And the gentle manufacturers are trying to ignore mentioning their bonics often have tinier images?
Reply With Quote Share with Facebook
  #33  
Old 07-04-2013
Senior Member
 
Join Date: Jan 2008
Posts: 393
Thanks: 1
Thanked 4 Times in 4 Posts
Rep Power: 7
noelex77 is on a distinguished road
Re: Binocular Conundrum: Field of View?

Quote:
Originally Posted by hellosailor View Post

noelex, you totally misread me. I never mentioned the pupil, as in the pupil of the eye, as being a factor in this. What I said was the the EXIT PUPIL of the binocs is all the same, and THAT is stated to be a limiting factor by all the binoc makers. That is, the field of light coming out of the binocs is constrained to a circle 4.2mm in size at the point where is focuses on the retina. (At least, that's how some of them define it.)
?
The same comments apply to the exit pupil.( not surprisingly as this should coincide with the eyes pupil). All the image goes through all parts of the exit pupil. If we chop off part of the exit pupil we do not loose part of the image, the image just becomes less bright.

The exit pupil is not on the retina. It has nothing to do with the retina. It is is the same position as the eyes pupil (technically slightly incorect, but close enough without confusing the issue)

The exit pupil can be the same size with a very different FOV. We can reduce the exit pupil without effecting the FOV.

If we chop of some of the light in front or behind the exit pupil we will loose some image. This is why its important the position of the binoculars exit pupil ( the eye relief) at the the same position as eyes pupil, otherwise if the eyes pupil is smaller than the light circle parts of the view will be obscured so the FOV will be reduced.
This is why people using glasses need binoculars with a long eye relief. The glasses move the eyes pupil further back and the exit pupil of the binoculars must be also be moved back or portions of the image will be cut off.
The eye relief is the position of the exit pupil of the binoculars and this should match the position of the eyes pupil.

Last edited by noelex77; 07-04-2013 at 05:43 AM.
Reply With Quote Share with Facebook
  #34  
Old 07-04-2013
capta's Avatar
Master Mariner
 
Join Date: Jun 2011
Location: somewhere in the Windward or Leeward Islands
Posts: 1,433
Thanks: 13
Thanked 68 Times in 63 Posts
Rep Power: 4
capta is on a distinguished road
Re: Binocular Conundrum: Field of View?

I'm a bit late on this thread, perhaps you haven't purchased a pair yet?
I broke down and paid the "big" bucks on the stabilized binos and am very happy I did. You can get more powerful ones (10 or 12 X magnification verses 8, the standard for small craft) as the stabilizing really does work and field of vision is not a factor when you can stay on target.
Again, this is another (of few) new items that greatly exceeds the hype, in performance.
My $650.00 8X50 rubber coated "marine" binos w/ compass never get used any more.
__________________
"Any idiot can make a boat go; it takes a sailor to stop one." Spike Africa aboard the schooner Wanderer in Sausalito, Ca. 1964.
Reply With Quote Share with Facebook
  #35  
Old 07-04-2013
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,601
Thanks: 2
Thanked 87 Times in 85 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: Binocular Conundrum: Field of View?

"The exit pupil is not on the retina. It has nothing to do with the retina. It is is the same position as the eyes pupil (technically slightly incorect, but close enough without confusing the issue)"
I understand that. But in this context, all eyeballs are the same size and all retinas are the same size, and that puts them all in the same position/geometry in relation to the exit pupil of the binocs. If the binocs had a 50mm wide exit pupil--it wouldn't matter because the iris would cut off the image at ~6mm and the retina can only accomodate a certain image size, no matter what angle the image entering the eye is "expanding" to.
The size of the retina is a limiting factor. The length of the eyeball is a limiting factor. The size of the iris is a limiting factor. The exit pupil size is another limiting factor--and the only relevant one that can be changed by the binoc maker, within limits.

Capta, I have purchased bincos. Many years ago. I'm looking for something a little different now, and I don't want image stabilized. There's moving parts and electronics and stuff to break in there. I was po'd when an internal lens (prism?) shattered in my binocs one winter, while they were stored in the closet. Apparently it was mounted ever so slightly too tightly and after enough years--the tension shattered it. Nice suprise, huh? So, I'll stick to the ones with no moving parts and just borrow or oggle yours.(G)
Reply With Quote Share with Facebook
  #36  
Old 07-04-2013
tdw's Avatar
tdw tdw is online now
Super Fuzzy Moderator
 
Join Date: Oct 2006
Location: Sydney Australia
Posts: 14,394
Thanks: 5
Thanked 67 Times in 62 Posts
Rep Power: 10
tdw is a jewel in the rough tdw is a jewel in the rough tdw is a jewel in the rough
Re: Binocular Conundrum: Field of View?

Quote:
Originally Posted by Cruisingdad View Post
Yep. Somehow it got dropped in the Kids forum. I blame TDW. Not sure why, but he makes a nice target.

Carry on!

Brian
Carefull CD or we'll bring speedo encased ape genitalia out into the open .... and you wouldn't want that now would you ?
__________________
Andrew B

"Do you think God gets stoned? I think so... Look at the platypus." Robin Williams.
Reply With Quote Share with Facebook
  #37  
Old 07-04-2013
Senior Member
 
Join Date: Jan 2008
Posts: 393
Thanks: 1
Thanked 4 Times in 4 Posts
Rep Power: 7
noelex77 is on a distinguished road
Re: Binocular Conundrum: Field of View?

Quote:
Originally Posted by hellosailor View Post
"The exit pupil is not on the retina. It has nothing to do with the retina. It is is the same position as the eyes pupil (technically slightly incorect, but close enough without confusing the issue)"
I understand that. But in this context, all eyeballs are the same size and all retinas are the same size, and that puts them all in the same position/geometry in relation to the exit pupil of the binocs. If the binocs had a 50mm wide exit pupil--it wouldn't matter because the iris would cut off the image at ~6mm and the retina can only accomodate a certain image size, no matter what angle the image entering the eye is "expanding" to.
The size of the retina is a limiting factor. The length of the eyeball is a limiting factor. The size of the iris is a limiting factor. The exit pupil size is another limiting factor--and the only relevant one that can be changed by the binoc maker, within limits.
)
The exit pupil does not limit the field of view.

Nor does the size of the retina, or the size of the iris.

The whole of the FOV passes through each point in the exit pupil. The exit pupil and/or the iris could be made minutely small and the FOV would be unchanged (but the image would be very dull)

The binocular manufacturer can modify the FOV without altering the exit pupil size.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Solar Conundrum GilStump Gear & Maintenance 13 07-28-2012 02:34 AM
Binocular Suggestions Vitesse473 Gear & Maintenance 53 03-20-2009 06:12 AM
binocular reticle sailorman_10 General Discussion (sailing related) 2 01-05-2004 05:06 AM
binocular rangefinder sailorman_10 Gear & Maintenance 0 12-24-2003 04:49 AM
Fugi Binocular Question vikinglady Gear & Maintenance 1 03-29-2002 07:11 AM


All times are GMT -4. The time now is 09:23 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.