• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Omid's Invention - Binoculars with Convergent or Divergent Field of View (1 Viewer)

Personally I found the much wider horizontal field than vertical field with the 6x18 binoculars not pleasant.
This may be because the eyepieces were basic and that special eyepieces need to be used.

I much prefer an EWA eyepiece binocular with normal circular images.

Because our eyes have much wider horizontal fields does not mean it is an easy job applying this to binoculars.
Our eyeballs are spherical yet we can precisely judge straight lines although they are curved on our retinas. It probably takes a long time as babies before our brains get images 'correct'.
This may also apply to the proposed wider horizontal field binoculars suggested.
 
Hi Lars,

Thank you very much for your exhaustive and detailed comments. I keep learning from your posts.

You're welcome!

Now, regarding the point that wedge prisms must be aligned so that they only induce horizontal change in the angle of view, I agree completely. The prisms must be connected to the binoculars (and potentially to each other via a rod) so that their orientation always remain base-in or base-out (whatever was designed originally) when the IPD distance of the binoculars are adjusted by the user. In most binoculars, the barrels rotate about the optical axis when IPD is adjusted. The prisms should be excluded from this rotation.

True, and I actually didn't think of the added complication of the resulting base up/down effect due to rotation when IPD is adjusted.


Nowhere in my design do I require the user to diverge his eyes. When I suggest that the real field of view of the binocular objectives are made slightly divergent, this still requires the user to converge his eyes to see an object located at a far -yet finite- distance. Consider a point object positioned in front of the binoculars and perfectly centered with respect to the two barrels. With normal binoculars (parallel fields of view), this point object will appear on the right side of the image in the left barrel and to the left side of the image in the right barrel. Now, if the field of view of the objectives are made slightly divergent using thin wedge prisms as I suggest, the same point object still appears on the right side of the center of image in the left barrel and on the left side of the image on the right barrel. What changes is that you need even more convergence to view it since the image moves farther from the centers and closer to the edges of the image shown in the eyepiece.
Excuse me, but I'm lost here. I understand that your main goal is to increase the resulting true field of view by reducing the common area seen with both eyes. Your analysis that the image of an object will be seen closer to the medial parts of the respective FOV's is correct. It is also correct that this requires added convergence, but I'm puzzled why you seem to consider this an advantage.
A traditional porro does almost exactly this when used at finite distance.
Once the right and left image of the object gets too close to the medial edge of the FOV, visual discomfort appears. This may be the result of either excessive convergence strain or difficulty to center the object in the narrow almond-shaped common area. That's why IPD adjustment helps. That's also why wide FOV's make traditional porros reasonably useful even at fairly close distance.
A traditional porro's best asset is the wide spacing between the objectives, where the added parallax will enhance the 3D perception.
It is not the convergence of the eyes that enhance the 3D perception.

The figures don't show the beams that are observable or usable to human eyes. The diagrams show, in very simplistic ways, how the prisms affect the direction of central light rays (the direction of view).

And you got the effect right - the light bends towards the prism base in your Fig. 2(a).
If you put base in prisms like in that figure, or for that matter one prism (makes no difference if you spread the prism power on one or two prisms), the eyes must diverge to not deliver a double-image.
Re the Fig. 3(b) regardless of whether it's central or peripheral light rays, when they converge like that, they don't come from the same object, i.e. diplopia will occur.

Regards,

Lars
 
The Minolta 6x18 UC and 8x18 binoculars have an oblong field.
This is, I think, achieved by having oblong field stops in the eyepieces.

The reason I don't like mine is mainly because the sliding case IPD adjustment catches my fingers. Someone else said his doesn't, so maybe only some do this.

The field stops could be any shape so long as the IPD adjustment was sliding not rotational.
 
Omid,

Would not the use of prisms in this manner result in severe chromatic dispersion?

Ed

Hi Ed,

Yes, there will be some dispersion and a small amount of astigmatism to deal with. But these have well-known solutions: For dispersion, the prisms can be made achromatic. Or one can use low-dispersion glass. Also, both dispersion and astigmatism can be corrected by having prisms in front of the objectives and after the eye pieces such that a) they produce deviations in opposite direction and b) the power of the prisms after the eyepieces are N-times larger than those in front of the objective. N here is the magnification of binoculars.

Other techniques can be used to correct for errors as well.
 
Last edited:
Omid,
Congratulations on your inventions.
I note that the query has been already made (by Looksharp65/Lars) whether there are functioning models. Sorry but I am not able to easily find the answer somewhere (hidden, to me!) in the posts above.
How well do these divergence and convergence designs work in practice in the instruments made until now? I know that for a patent a model has to work but not how well the invention has to be working already in typical use.
Have you watched birds or nature through them and if so what did you think? (I mean only the optical aspect, of course, not the ergonomics.) Thank you!
Adhoc
 
Last edited:
Hi Ed,

Yes, there will be some dispersion and a small amount of astigmatism to deal with. But these have well-known solutions: For dispersion, the prisms can be made achromatic. Or one can use low-dispersion glass. Also, both dispersion and astigmatism can be corrected by having prisms in front of the objectives and after the eye pieces such that a) they produce deviations in opposite direction and b) the power of the prisms after the eyepieces are N-times larger than those in front of the objective. N here is the magnification of binoculars.

Other techniques can be used to correct for errors as well.


It sounds pretty complicated ....

Ed
 
Hi Omid - one of your innovations in the other thread looks, to me anyway, more interesting than the thread subject. Could an eyepiece designed to achieve this be made to the dimensions of current binocular eyepieces and would it offer comparable resolution etc?

I have made some innovations myself:

a) Binoculars without a critical eye relief. The exit pupil is located at the eyepiece and is as large as the eyepiece. This way, the entire eyepiece shows an image when viewed from behind the binoculars. The image is visible even if you position your eyes on an off-axis position.
 
Hi Omid - one of your innovations in the other thread looks, to me anyway, more interesting than the thread subject. Could an eyepiece designed to achieve this be made to the dimensions of current binocular eyepieces and would it offer comparable resolution etc?


Hi. The invention you are referring to does not require a special eyepeice. The invention changes the numerical aperture of the beams delivered to the eyepeice. The result is an image that can be seen from a wide angle and from almost any distance from behind the eyepiece. (In the picture below, the left barrel of the binocular uses that invention. The right barrel is normal.)

Yes, very high resolution can be achieved. There will be some loss in brightness due to light from any image point now being distributed to wider angles behind the eyepeice.
 

Attachments

  • Expanded_EyeRelief.jpg
    Expanded_EyeRelief.jpg
    45.6 KB · Views: 142
Omid,
Congratulations on your inventions.
I note that the query has been already made (by Looksharp65/Lars) whether there are functioning models. Sorry but I am not able to easily find the answer somewhere (hidden, to me!) in the posts above.
Adhoc

Thank you! Yes, I think Lars had asked this question too and I did not answer it before. I did make some test prototypes using off-the shelf wedge prisms bought from Edmund Optics. I noticed that my ideas work in principle, just need refinements (e.g. using achromatic prisms instead of plain ones I had) so I went ahead with the patent application.

I also used indirect evidence (from other devices or fields of optics that I am familiar with) to check the validity of the concepts. Of course the final product needs to be fully tested and may need additional optical elements but that can be done by the brand or the manufacturer who licenses the design.

As an inventor, it is not my duty to make the best and final optical design of the invention. It is my duty to describe the key elements and their interrelation such that the resulting device is "novel". I also need to explain what this novel device does. US Patent and Trademark Office does not require a working prototype of an invention. (It did in very early years of its operation). It requires a detailed description of the invention accompanied by drawings such that "a person of ordinary skill in the art" can make and use the invention.
 

Attachments

  • Wedge_Prisms.jpg
    Wedge_Prisms.jpg
    201.9 KB · Views: 78
Last edited:
Omid, Thank you for that really useful explanation regarding a patent in the USA nowadays. (Also for the thumbnail. The view is already improved!)

Yes, an inventor would not always him/herself optimize the invention. But as you write in Birdforum I assumed you are a bird watcher and thought you might like to a.s.a.p. experience the view being actually enhanced.

It seems there is a bit of a contradiction. For "a person of ordinary skill in the art" (Pat. Ofc's words) to "make and use the invention" (your words) the refinements need to be effected. Anyway, I hope that these ordinary people, or others more appropriate, will get on with it!
 
Excuse me, but I'm lost here. I understand that your main goal is to increase the resulting true field of view by reducing the common area seen with both eyes. Your analysis that the image of an object will be seen closer to the medial parts of the respective FOV's is correct. It is also correct that this requires added convergence, but I'm puzzled why you seem to consider this an advantage.
A traditional porro does almost exactly this when used at finite distance.
Hi Lars,

Sorry for my delayed response. Lets consider a test case: A typical 10X50 roof binocular has 6.6 degree real field of view. This corresponds to 110m at 1000m. If we use a Porro bincular of comparable optical design with inter-barrel distance of 1m, the binocular field of view increases to 110m + 1m at 1000m. This is negligible.

But if we use my invention and diverge the fields of views of the left and right barrels each by 1 degree, the binocular field of view at 1000m increases by 35m. This is 30% more real field of view. ;)
 

Attachments

  • Finch_Field_of_View.jpg
    Finch_Field_of_View.jpg
    24.8 KB · Views: 63
Last edited:
Hi Lars,

Sorry for my delayed response. Lets consider a test case: A typical 10X50 roof binocular has 6.6 degree real field of view. This corresponds to 110m at 1000m. If we use a Porro bincular of comparable optical design with inter-barrel distance of 1m, the binocular field of view increases to 110m + 1m at 1000m which is negligible.

But if we use my invention and diverge the fields of views of the left and right barrels each by 1 degree, the binocular field of view at 1000m increases by 35m at 1000m. This is 30% more real field of view. ;)

Hi Omid!
I haven't claimed that the porro's wider spaced objectives increases the binocular's FOV, but the parallax difference is significant at medium and close distance which enhances the 3D perception.

Your drawing of the increased FOV resulting from diverging optical axises looks correct.
In theory, the common, almond-shaped central part of the FOV could coincide fairly well with the human FOV.

However, the binocular part of the human FOV covers about 120 degrees horizontally.
If the binoculars in your examples have wide angle eyepieces, each of them would cover say 75 degrees (apparent field of view).
This means that the fieldstops by default limits the usable FOV by at least 20 degrees towards each side.

Any divergence of the tubes will further shrink the common (shared) area and expand the monocular area.
I assume your drawing is exaggerated to show the effect more clearly, but only a third of the FOV is shared there.

If we take into account that the eyes ideally scan a scene and prefer to roam freely, it's apparent that they will meet the fieldstops earlier than in an ordinary binocular.
The user would probably react with turning the binoculars further towards the point of interest, hence losing what's happening at the other end of the FOV and losing the very reason for using this invention.

This said, if the divergence is kept very low, and the optical challenges could be met, it might work as you described, with only minor inconvenience of the types in my objections. It would take eyepieces with huge AFsOV to compensate the loss of the common FOV as much as possible, and such binoculars already make a great job. I'm mostly thinking about the Nikon EII series, but wide angle constructions from the seventies with "up to and above" 80 degrees AFOV are also interesting in this context.

Regards,

//L

Edit: added a drawing that Ed originally provided me in another discussion.
 

Attachments

  • visual_fields.jpg
    visual_fields.jpg
    21.9 KB · Views: 69
Last edited:
I agree Lars.

In addition, although the vertical FOV of the eyes is limited, the view is still there, but blocked by our foreheads and eyebrows.
I realised this when wearing wrapround dark glasses and coming indoors saw a huge black area that was blocked.
It is our brains that deal with the areas blocked including the areas blocked by our nose. We should see these areas as black but don't.

With the 6x18 binocular the FOV is only 7.5 degrees, approx 45 degree AFOV. I did not like the view with vastly extended horizontal view even though centrally I got stereo vision.
I much prefer 75 to 80 degree AFOV older Porroprism binoculars and normal views.
 
Hi Omid!
However, the binocular part of the human FOV covers about 120 degrees horizontally... If the binoculars in your examples have wide angle eyepieces, each of them would cover say 75 degrees (apparent field of view).
This means that the fieldstops by default limits the usable FOV by at least 20 degrees towards each side.... Any divergence of the tubes will further shrink the common (shared) area and expand the monocular area.
I assume your drawing is exaggerated to show the effect more clearly, but only a third of the FOV is shared there.

Hi Lars,

Sorry again for late response. You points are all valid. We should also consider the field stop and its effect on limiting the apparent field of view. Yes, in my design there will be less overlap between the left real field of view and the right real field of view at far distances. But that's fine, it is not an issue. When you yourself talk about the nice 3-D effect of a porro prism binocular at short and median distances, that's exactly what happens in those situations too: the left barrel view and the right barrel view don't make a full overlap at short distance. The eye naturally focuses on ONE OBJECT at the center and the rest is peripheral vision. (Try it yourself, look at a flower 2m away using your 10X binoculars)

There is also another degree of freedom in my design: You can create the effect of diverging/converging objective lenses and diverging/converging eyepiece lenses in any desired combination! So, many interesting - and some potentially usefull- effects can be created by this design. We have discussed two potential use cases so far:

  1. providing more real fielf of view when viewing far objects
  2. decreasing apparent convergence when viewing close objects

Let's think about it and figure out what else can be done? ;)

Thanks,
-Omid
 
When you yourself talk about the nice 3-D effect of a porro prism binocular at short and median distances, that's exactly what happens in those situations too: the left barrel view and the right barrel view don't make a full overlap at short distance. The eye naturally focuses on ONE OBJECT at the center and the rest is peripheral vision. (Try it yourself, look at a flower 2m away using your 10X binoculars)

Again, it is not the horizontal-medial displacement of the image per se that creates a better 3D perception, it is the real parallax that's greater when the objective lenses are further apart. The medial image displacement is a side effect of the parallax. So while a slightly larger total (while not binocular) FOV could be obtained, the benefits of a better 3D view of a porro design will not be gained.

There is also another degree of freedom in my design: You can create the effect of diverging/converging objective lenses and diverging/converging eyepiece lenses in any desired combination! So, many interesting - and some potentially usefull- effects can be created by this design. We have discussed two potential use cases so far:

  1. providing more real fielf of view when viewing far objects
  2. decreasing apparent convergence when viewing close objects

Let's think about it and figure out what else can be done? ;)

Thanks,
-Omid

The benefits of a decreased parallax for close viewing are clear and apparent when using reverse-porro design binoculars. The Papilio takes it a step further with its physically converging tubes coupled to the focus setting.

When you mention "your design" I take it you plan to combine these two advantages by utilising a design with flipping prisms.
I think it's time to produce a simple model to back your claims.

The technical challenges aside (they have been mentioned earlier in the thread) but the simplest of models, using trial lenses in front of the objective lenses and behind the ocular lenses, would be enough to assess whether or not your ideas rest on firm ground and whether or not they they can produce real and unrestricted advantages for each of these two situations.

The requirements to back your claims would be:
A visibly larger FOV beyond what's obtainable with super wide angle eyepieces, coupled with binocular near vision at about 40 cm with a minimum real eye convergence like the Papilio design.
When assessing the general effect of prisms, single-side mounting is sufficient. I'm interested to learn about the progress.

//L
 
Last edited:
Hi Lars,

This discussion and the diagram on post #33, prompted me to reexamine my superb Linet Imperial 8x40 Fieldmaster. It was made by Hiyoshi Kogaku in the early 1980s and has a real field of 12 deg., or an apparent field of 96 deg. That's 96 deg. for each eye!! I mention this because when the instrument is set to my IPD (165 mm.) there is no way that the two fields can overlap completely. This is evident by the oval shape of the combined field-stops, and that the horizontal edges provide only monocular images. I would estimate that the combined, binocular, field-of-view is approximately 96+25 = 121 deg., with a central overlap area of 70 deg. (Unfortunately, the eye relief is very short (~10-12 mm) so viewing with spectacles is out of the question.)

I'd have to ask Omar if this can be equalled or exceeded with his innovation. A related question is whether or not this extreme FOV is even beneficial for birding or astronomy? I guess there might be an advantage for detecting peripheral motion.

As you say, without a working specimen this involves a bit more imagination than I can rely on.

Ed
 
Last edited:
Hi Ed,
I don't know how serious you are here.
With a 165mm IPD I suppose you are about 14ft tall.
This must be useful for viewing in crowds.

Have you actually measured the field? Maybe someone who doesn't use glasses could measure it.
Do the 4 stars of the Ursa Major bowl fit in the field at the same time.
Have you measured the magnification and how it varies across the field?

EWA or SWA binoculars are useful. They allow meteors to be seen that would be missed and peripheral movement to be seen.
 
Hi Ed and Lars,

Thank you very much for your recent notes and comments.

@Ed: Please note that I don't intent my concept to "replace" wide-field binoculars, my idea can be combined with a wide field eyepiece. You are right in that additional peripheral visions may not be useful in birding but there are many applications that do benefit from enhanced peripheral vision (hunting, military, general field observations). You focus on your target at the center and at the same time remain aware of movements or other activity in a wide field of view.


In response to Lars comment I have to clarify that the two advantages I mentioned, would be best provided in separate products. I don't intend to combine reduced convergence and increased field of view in a single design (although it is possible to do so by making the invention in the form of an attachment that you connect to existing binoculars).

A main reason I posted about my invention here is to do exactly what we are doing: making mental experiments and extrapolating from known concepts using our imagination. We have not fully explored the concept of "capturing an stereoscopic view" using divergent or convergent objective lenses and then "presenting said captured views" to the human eyes using convergent or divergent eyepieces. Note that these are two separate concepts. We can use similarities to 3D photography to predict what will happen in each case.


Another comment in response to Lars: You call increasing the distance between objective lenses "true parallax" and tilting the view angle of the object lenses, "fake parallax". I would agree to some degree with this designation but we have not proven yet that the latter method would not produce enhanced 3D view. This method has actually been used for making 3D pictures using a single camera and it works (you can simply rotate the whole scene by a small angle and take a second picture with same camera position). Some amount of keystoning error results from doing this but this is minimal at far distances (application 1) and can be corrected in application 2.

Also see the great article here which articulates the effects of having a convergent direction of view. So, lets continue the mind experiments and extrapolations a bit more. I am sure we might discover some interesting things...

Regards,
-Omid
 
Last edited:
Hi Ed,
I don't know how serious you are here.
With a 165mm IPD I suppose you are about 14ft tall.
This must be useful for viewing in crowds.

Have you actually measured the field? Maybe someone who doesn't use glasses could measure it.
Do the 4 stars of the Ursa Major bowl fit in the field at the same time.
Have you measured the magnification and how it varies across the field?

EWA or SWA binoculars are useful. They allow meteors to be seen that would be missed and peripheral movement to be seen.

Now, now my friend it was only a slip in my keypad. My IPD is a mere 65 mm, and my height has now shrunk to only 6 ft. ;)

I never got into astronomical viewing, and now my eyes are growing dim. So next time around I'll put it at the top of my bucket list.

No, I've trusted the manufacturer to the 12 deg. designation. Hiyoshi is pretty good with that sort of thing, and this instrument is every bit as fine as any Audubon I've handled. ($10 at the Thrift Shop, with leather case. :king:) At first use I came away disoriented and headachy, and thought it needed alignment; but then realized that I was setting the IPD by making the field stops overlay in a circle. Bad, bad. Setting the IPD by ruler was the answer, or the calibrated scale. Unfortunate that the ER is so short.

But you agree with me that the extra field width basically helps with peripheral movement detection.

Regards,
Ed
 
Warning! This thread is more than 6 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Users who are viewing this thread

Back
Top