3D in roof prism binoculars (1 Viewer)

[SuperDuty]

When someone describes a pronounced 3D view in a roof, the Zeiss HT and SF most recently, what combination of optical traits would be the reason for what they see. It's always been my understanding that 3D is exclusive to the Porro binocular due to the wider objective spacing.

Robert

 

[Binastro]

Hi Robert,
. The 3-D effect is also dependent on the magnification and the distance to what you are looking at.
If there are a lot of objects, near to each other, then the 3-D effect also depends on the relative distance to these different objects.

Persons with good eyesight can see 3-D effects without optical aid up to well over 100 yards, in some cases up to 600 yards.

Even with reverse Porro prism binoculars I clearly see 3-D effects despite the fact that the objectives are close to each other. This is mainly due to the magnification.

 

[henry link]

All binoculars have some stereopsis. Traditional Porros have more than roofs or reversed Porros because the baseline between objectives is wider.

I'm also curious about reports of more or less "3-D" in roofs with the same magnification and baseline. These can't reflect true differences in stereopsis unless the baselines are actually different, which they could be in some roofs. AK prisms, for instance, usually have a little wider baseline than the viewer's IPD and sometimes SP's have a little narrower baseline than IPD. If the baselines are identical I think any extra "3-D" is likely to be ersatz, perhaps generated by differences in the off-axiss aberrations or distortions seen by each eye. I have a very large magnifying glass that allows me to view flat pictures with both eyes. Sometimes I see spurious "3-D" effects when viewing pictures through the magnifier when each eye is looking through a different part of the lens. If I switch back and forth between eyes I notice objects in each eye have slightly different shapes, amounts of lateral color, etc.

 

[Binastro]

. When viewing a bright full moon in a clear sky and using a good example of the Russian 20×60 binocular, I get a very strong stereoscopic view of the Moon. The Moon looks really beautiful in 3-D.

The Moon is about 240,000 miles away, so this is some kind of illusion either from the binocular, my eyes or both.

Also, when viewing a flat image even on a computer screen of certain strong colours, like red green and blue with discreet sharp boundaries between them, I also see the image in 3-D. Sometimes this effect is stronger than at other times. I've been told that this is because of the chromatic aberration of the eye.

 

[henry link]

Right, Binastro. I notice that some astronomers also report a stereoscoptic effect on the moon and planets when viewing through a telescope equipped with a bino-viewer. Obviously no true stereopsis there.

 

[OPTIC_NUT]

Seeing a 3D effect on the Moon, 240,000 miles away is something other than
stereopsis. If the magnification is slightly different from side to side you would get a strong 3D effect.
If one side is a little de-focused, that might trick the cortex, too.

Maybe the eye....if the aberration or correction were different, eye to eye.
Could happen with astigmatism. 3D just happens when trying to match
'almost same' images.

 

[kkokkolis]

I percept the moon at 3D with Canon 18x50. I believe it's a combination of shadows and mental projection.
Any close object with Pentax Papilio and my roofs is strongly 3D. Here parallax plays the major role. By closing each eye in alternate manner you can see that the closer the object the most different the view of it by each eye. Items in the horizon or the celestial sphere have parallax close to zero.

 

[Theo98]

Stereoopsis & 3D

All binoculars have some stereopsis. Traditional Porros have more than roofs...I'm also curious about reports of more or less "3-D" in roofs with the same magnification and baseline.

Interesting Henry...I never though about baseline differences between like powers (except in the obvious poros). :h?:

Would roofs having larger objectives, but sharing equal powers (ex:10x30 vs 10x42 vs 10x50 vs 10x56mm, etc.) have inherently wider baselines that heighten\widen the stereoscopic effect, thus creating a more pleasing and natural visual space?

 

[OPTIC_NUT]

The baseline on a roof is always the same: your IPD.

 

[henry link]

Interesting Henry...I never though about baseline differences between like powers (except in the obvious poros). :h?:

Would roofs having larger objectives, but sharing equal powers (ex:10x30 vs 10x42 vs 10x50 vs 10x56mm, etc.) have inherently wider baselines that heighten\widen the stereoscopic effect, thus creating a more pleasing and natural visual space?

Well, roofs with wider baselines will create a more Porro like presentation, if you consider that more pleasing and natural. Wider objective baselines are probably confined to roof prism binoculars with AK prisms and larger ones will probably have the widest baselines, but measuring is the only way to know for sure. My 8x42 FL with AK prisms has an objective baseline about 7mm wider than the IPD setting while my 8x56 FL has an objective baseline about 13mm more than IPD. It's surprising how noticeable those small differences are regarding stereopsis and apparent magnification at close focus compared to inline roofs. SP objective baselines will usually be the same as IPD, but may occasionally be a little wider or narrower. I recall that the 8x32 Nikon Premier XL has an objective baseline about 5mm narrower than IPD and that is also surprisingly noticeable compared to inline roofs.

Henry

 

[elkcub]

When someone describes a pronounced 3D view in a roof, the Zeiss HT and SF most recently, what combination of optical traits would be the reason for what they see. It's always been my understanding that 3D is exclusive to the Porro binocular due to the wider objective spacing.

Robert

Unfortunately, a number of terms are used in a rather loose way, resulting in a great deal of confusion. Stereopsis can be succinctly defined as [that aspect of] depth perception provided by fusion of binocular images." Depth perception, however, is a broader term referring to "...the visual ability to perceive the world in three dimensions (3D) and the [distance of objects]." As discussed in the second Wiki article, therefore, stereopsis is only one of several visual cues used by the brain for 3D depth perception, and although very important it can be done without, e.g., a person having only one eye. Even with both eyes working, however, all monocular cues are involved with 3D vision, in particular perspective cues that, using a binocular, are influenced by the size of the field of view. Although hardly ever discussed, one that is very much compromised by a narrow field binocular is curvilinear perspective.

In any event, 3D vision and depth perception is by no means confined to Porro binoculars, although they do provide a wider stereo base that will have the greatest stereopsis effect at intermediate working distances. However, at close working distances they progressively interfere more with convergence cues than do modern roofs that allow 1m± viewing. At far working distance they have virtually no effect at all. Of course, it could be argued that intermediate working distances are the most important for birders, and that may be true. (It may also be true that Porro owners like to look where there is the greatest stereopsis effect. I can't decide.

Ed

 

[elkcub]

Well, roofs with wider baselines will create a more Porro like presentation, if you consider that more pleasing and natural. Wider objective baselines are probably confined to roof prism binoculars with AK prisms and larger ones will probably have the widest baselines, but measuring is the only way to know for sure. My 8x42 FL with AK prisms has an objective baseline about 7mm wider than the IPD setting while my 8x56 FL has an objective baseline about 13mm more than IPD. It's surprising how noticeable those small differences are regarding stereopsis and apparent magnification at close focus compared to inline roofs. SP objective baselines will usually be the same as IPD, but may occasionally be a little wider or narrower. I recall that the 8x32 Nikon Premier XL has an objective baseline about 5mm narrower than IPD and that is also surprisingly noticeable compared to inline roofs.

Henry

Hi Henry,

My 8x42 SLC-HD has a 3.5 mm wider objective base than it's IPD. My 8x30 SLC has the same objective base as its IPD. They both use SP prisms, and have the same FOV. I can see no obvious difference in stereopsis (assuming I could separate it out from other depth effects). Maybe 3.5 mm is too small to discriminate (2.1%). I have a feeling that some of these reported effects may also result from FOV differences.

Ed

 

[OPTIC_NUT]

I was thinking in a very different ballpark...

I measure an IPD setting of 63mm and objectives 135mm apart on-center for
my favorite 10x50 Porros.

And... 63mm IPD with 116mm on-center axis difference for my favorite 8x40 Porros.

Now, that's what I call an objective base.
Rangemasters are a different story, but quite rare.
These are just run-of-the-mill Porros I measured.


The Meopta MeoPro 6.5x32s (roof) show an objective base of 63mm when set for IPD of 63mm.

 

[Theo98]

The baseline on a roof is always the same: your IPD.

Thanks gentleman...Got It! :t:

 

[Pinewood]

Hello,

The Zeiss binoculars with Abbe-König do provide stereopsis as those prisms provide a slightly larger distance between the objectives than between the eyepieces. Therefore I would expect the HT's to show some stereopsis, as does my 7x42 Dialyt.

Happy bird watching,
Arthur Pinewood :hi:

 

[OPTIC_NUT]

They all show some stereopsis.
Porros a bit more, if artificially (your brain thinks you are a moose, or that things are all farther away).

Things to bear in mind:

----Past a hundred yards or so, there is no real 3D effect either way.
----If you are focusing close-up, the Porro axes get noticeably out of alignment much farther out
than the roof. For 10 to 100 feet, for example, a roof set will be more aligned view-to-view, and
more comfortable. Not such thing as a free lunch with 3D.

 

[Tobias Mennle]

Beyond true 3d effect/stereopsis, as with contrast, there is our perception of it, and I think there is much more to it than just baselines. Probably field curvature and distortion is very important, my favorite example would be Swarovision vs Zeiss SF, with the Zeiss looking more 3D and having much more of a curved field.

Here is one of my favourite pieces that fits well with my binocular testing. The guy is a Hollywood director of photography and does a lens test in 2D. Important part is in-between 2:20 and 5:00, it´s really nice to hear this passionate argument against flat field and pro curved field, although the images may look more convincing on a 40 foot seen.

https://vimeo.com/90168989So he compares the latest state-of-the-art Leica flat field lenses to the classic Cooke S4 primes with curved field. His verdict: The Leicas are only good for shooting sheet metal. For faces he wants Cookes, because they render way more three-dimensional. Again, we are talking about 2D films, so true stereopsis is not the subject.

Indeed, the Cookes are legendary and I did notice how great they render when watching Blurays, the Cookes are easy to track because of their special aperture shape that turns up in the bokeh highlights.

 

[OPTIC_NUT]

Sounds like the Cookes may generate artifacts that provide edge clues,
or maybe increase other atmospheric distance effects.

 

[elkcub]

Beyond true 3d effect/stereopsis, as with contrast, there is our perception of it, and I think there is much more to it than just baselines. Probably field curvature and distortion is very important, my favorite example would be Swarovision vs Zeiss SF, with the Zeiss looking more 3D and having much more of a curved field.

Here is one of my favourite pieces that fits well with my binocular testing. The guy is a Hollywood director of photography and does a lens test in 2D. Important part is in-between 2:20 and 5:00, it´s really nice to hear this passionate argument against flat field and pro curved field, although the images may look more convincing on a 40 foot seen.

https://vimeo.com/90168989So he compares the latest state-of-the-art Leica flat field lenses to the classic Cooke S4 primes with curved field. His verdict: The Leicas are only good for shooting sheet metal. For faces he wants Cookes, because they render way more three-dimensional. Again, we are talking about 2D films, so true stereopsis is not the subject.

Indeed, the Cookes are legendary and I did notice how great they render when watching Blurays, the Cookes are easy to track because of their special aperture shape that turns up in the bokeh highlights.

Tobias,

Thank you so much for the remarkable video! It demonstrates what I have simply been unable to put into words about how field flatteners compromise the view. What I didn't realize, and should have, is that they mess up the monocular cues.

Once seen, never forgotten. :t::t:

Ed

 

[Pileatus]

I'm a die-hard fan of "flat-field" views and I don't see any problems with 3D perception. My primary bin for many years was an 8X32 SE and I also use 8.5X42 and 10X50 Swarovisions. My wife owns an 8X32 SV which I use for comparisons. I used a 7X42 Ultravid for many years but those edges finally got to me as the years passed. The Ultravid, by the way, was quickly relegated to long distance viewing solely because of the distracting edges. When I first examined the 8.5X42 SV I knew immediately the Leica would find another home. For the record, the Leica is a superb instrument and my choice is solely a matter of personal likes and dislikes. I don't care if they use jello for lenses...if my eyes are happy, I'm happy.

PS
In the vimeo video the Leica always seemed to be a tad less sharp than the Cooke.

PPS
My wife says she doesn't care what happens to her once-beloved SE. Oh, the fickle nature of love!