Porro or Roof ? Your choice. (1 Viewer)

elkcub said:

Hi Brock,

I may have missed it, but I didn't read anyone on this thread saying one view is more "natural" than the other, ... and I thought Ronh summarized several notions rather well, although I might not subscribe to them all:



Judging by the fact that stereo binoculars were used during the European trench wars, presumably with good effect to improve distance estimation, I'm not persuaded that "insult is added to injury" by the larger stereo base afforded by Porros. Both Henry and Kimmo also appear to acknowledge the improvement to roof views with larger objective separations. So, ... no issue?

Frankly, I'm happily torn between my two favorites: (a) the 8.4x44 Swift 804ED, and (b) the Swaro 8x42 SLC HD. Vive la difference!

Ed

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"I'm not persuaded that "insult is added to injury" by the larger stereo base afforded by Porros."

Neither am I, but it sure seems like some were trying to prove that opinion objectively, and my point was, they can't.

Take Steve C., for example, who doesn't see the stereo effect of porros. Or those who don't see CA or RB or the "roof illusion". Or those who say the FL has a "blue bias" and those who don't. Or those who say the SE's color is neutral and those who say it has a "red bias".

Perceptions vary from person to person. They can even vary in the same person.

In these cases, "the numbers simply don't add up". :smoke:

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I have no opinion about which view anybody should favor. My remark about Porro fans being crazy was facetious (except for Brock). I even made an argument in favor of the Porro's strong 3-D enhancement, how's that for fairness? And I do believe that the Porro would help to pick a bird out of a dense background by accentuating distance differences. But I'm used to what I'm used to, can't help that.
Ron

ronh said:

I have no opinion about which view anybody should favor. My remark about Porro fans being crazy was facetious (except for Brock). I even made an argument in favor of the Porro's strong 3-D enhancement, how's that for fairness? And I do believe that the Porro would help to pick a bird out of a dense background by accentuating distance differences. But I'm used to what I'm used to, can't help that.
Ron

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You know it really depends on what you prefer. I compare my Swaro 8x32 EL and my Nikon 8x32 SE and they are both awesome views. It just depends on what you like better. I think it is personal preference. I like having one of each for a change. To my eyes the porro is a more realistic view than the roof but an alpha roof is still incredible. It just depends on what you like. Try them both. A porro is way less money though for the same quality of view. You can argue all you want but you can't go wrong with an alpha roof if you only have one binocular but if your budget is limited get a porro. If you got to have waterproof go with the roof or the Swaro Habicht.

Question – Roof prisms are now the norm in birding, hunting and travel binoculars for the reasons discussed. But are roof prisms used anywhere outside these applications?

Marine binoculars use porros. Astronomy binoculars use porros. Birding scopes use porros. Binocular microscopes use porros. The porro prism seems to be the image-inverting system of choice in all optical instruments apart from birding, hunting and travel binoculars.

Brigadier said:

Question – Roof prisms are now the norm in birding, hunting and travel binoculars for the reasons discussed. But are roof prisms used outside these areas?

Marine binoculars use porros. Astronomy binoculars use porros. Birding scopes use porros. Binocular microscopes use porros. The porro prism seems to be the image-inverting system of choice in all optical instruments apart from birding, hunting and travel binoculars.

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Just one small observation that doesn't detract from the point you are making: Zeiss's range of monoculars, including the close-focusing, ones all use S-P prisms.

Lee

brocknroller said:

"I'm not persuaded that "insult is added to injury" by the larger stereo base afforded by Porros."

Neither am I, but it sure seems like some were trying to prove that opinion objectively, and my point was, they can't.

Take Steve C., for example, who doesn't see the stereo effect of porros. Or those who don't see CA or RB or the "roof illusion". Or those who say the FL has a "blue bias" and those who don't. Or those who say the SE's color is neutral and those who say it has a "red bias".

Perceptions vary from person to person. They can even vary in the same person.

In these cases, "the numbers simply don't add up". :smoke:

<B>

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Brock,

You misunderstand. I see a 3-D effect in both roof and Porro prism binoculars. With a good Porro such as a Swift 804, the effect of the 3-D view will seem more pronounced than with some roofs.

For example my 7x36 Zen ED 2 appears to me to have as much stereo effect in its view as any porro.

Brigadier said:

Marine binoculars use porros. Astronomy binoculars use porros. Birding scopes use porros. Binocular microscopes use porros. The porro prism seems to be the image-inverting system of choice in all optical instruments apart from birding, hunting and travel binoculars.

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A tedious point, but not all birding scopes use porros.

Troubador said:

Just one small observation that doesn't detract from the point you are making: Zeiss's range of monoculars, including the close-focusing, ones all use S-P prisms. Lee

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Leif said:

A tedious point, but not all birding scopes use porros.

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Troubador, Leif,

Thanks for correcting me. I guess what I'm asking is:

• Are there any inherent performance advantages of roof prisms over porro prisms? (The ones we've discussed – compactness, ergonomics, ease of sealing and internal focusing – are all design/packaging advantages rather than performance advantages).
• Are roof prisms used in preference to porro prisms in any optical equipment other than consumer sports optics aimed at the nature watching, hunting and travel/leisure markets?

Brigadier said:

Question – Roof prisms are now the norm in birding, hunting and travel binoculars for the reasons discussed. But are roof prisms used anywhere outside these applications?

Marine binoculars use porros. Astronomy binoculars use porros. Birding scopes use porros. Binocular microscopes use porros. The porro prism seems to be the image-inverting system of choice in all optical instruments apart from birding, hunting and travel binoculars.

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Good question. Why?

Brigadier said:

Troubador, Leif,

Thanks for correcting me. I guess what I'm asking is:

• Are there any inherent performance advantages of roof prisms over porro prisms? (The ones we've discussed – compactness, ergonomics, ease of sealing and internal focusing – are all design/packaging advantages rather than performance advantages).
• Are roof prisms used in preference to porro prisms in any optical equipment other than consumer sports optics aimed at the nature watching, hunting and travel/leisure markets?

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Probably the stuff Henry has been saying with the roof having a better close focus and the image scale of a roof is larger.

To my eye, all optics that magnify have the effect of compressing space. If I look down the back side of a line of houses a quarter mile up the road, there is a basketball goal that looks to be behind a particular house, when in reality if you drive by the house, the goal is behind another house that is a good bit further up the road.

ronh said:

Henry's point about stereopsis is good, although it will hardly convince Porro fans that they are tolerating a bad situation. But while we're at it, let's examine how unnatural the magnified view is, at best.

Take his objects at 80' and 160' as the example again. We like to think that the binocular gives us a view that is just like we'd see if we walked over closer to the scene.

If we walk closer, so that we're now 1/10 as far from the closer object, that will be to a distance of 8", or 72' closer.

The more distant object will still be 88' away. But if it was viewed from the original location at 10x, its size would suggest that its distance had been shrunk from 160' to 16'.

88' and 16' are very different. Magnification alters perspective so that the separations between objects appears artificially compressed. Arguably, the unnatural 3-d enhancement could help restore some impression of depth to a scene that has had the depth sucked right out of it by magnification. Personally I feel that it only adds insult to injury.

Thank goodness, we get used to this stuff and worse, and smile thinking how natural the view in our own binocular looks, dealing also with eye positioning, field distortions, and focusing all in perfect stride, with a little practice. The brain is deadly efficient at ignoring stuff you don't want to see.

Yep, Porro fans must be crazy, what's wrong with them? The answer is, much worse things must be wrong with all of us!
Ron

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[email protected] said:

Probably the stuff Henry has been saying with the roof having a better close focus and the image scale of a roof is larger.

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I don't think close focus is an inherent advantage of roof prism systems.

In posts #37 and #38 of this thread, Henry reminds us that practical close focus is limited by parallax, so an inverse porro binocular, with its closely-spaced objective lenses, is better suited to close focus viewing (less than 2m/6ft, say) than any conventional roof or porro design.

So, what are the inherent advantages of roof prism systems – optical advantages, not design and packaging advantages?

PS. Moderator: As this thread isn't Nikon-specific, would it be better to move it to the general area?

Brigadier said:

I don't think close focus is an inherent advantage of roof prism systems.

In posts #37 and #38 of this thread, Henry reminds us that practical close focus is limited by parallax, so an inverse porro binocular, with its closely-spaced objective lenses, is better suited to close focus viewing (less than 2m/6ft, say) than any conventional roof or porro design.

So, what are the inherent advantages of roof prism systems – optical advantages, not design and packaging advantages?

PS. Moderator: As this thread isn't Nikon-specific, would it be better to move it to the general area?

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Regarding close focus, inverted porros are really only practical with small objectives. The parallel dog leg form is still rather clumsy for holding.

But do there have to be optical advantages to the roof prism? They are used for sound ergonomic and design reasons, as discussed earlier.

They sometimes require mirror coatings, always require phase correction coatings, and are harder to make due to higher tolerances on the angles. Modern mirror coatings can be near perfect, it would seem, and I can only assume the phase correction coatings are near enough to perfect to correct the phase shift introduced by the roof. I cannot think of an advantage (perhaps less dispersion?).

The new Perger roof prism clearly does have advantages when building a rangefinder instrument.

bh46118 said:

To my eye, all optics that magnify have the effect of compressing space.

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I agree. My binoculars flatten objects such as tree trunks and house roofs, so they almost look like cardboard cutouts.

For astronomy I use roof prisms as much as porros, it really makes little difference as long as the images are good quality.
It probably is easier to find things in roofs as you can sight along the barrels.
It is certainly easier to sight along a straight telescope rather than an elbow one.

Troubador said:

Just one small observation that doesn't detract from the point you are making: Zeiss's range of monoculars, including the close-focusing, ones all use S-P prisms.
Lee

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Lee,

that's a good and interesting point. The question is why do Zeiss (and most other manufactorers) only use S-P prisms with their range of monoculars? With monoculars the ascendancy of the S-P prism over the porro is still even greater than with binoculars.

Steve

Steve C said:

Brock,

You misunderstand. I see a 3-D effect in both roof and Porro prism binoculars. With a good Porro such as a Swift 804, the effect of the 3-D view will seem more pronounced than with some roofs.

For example my 7x36 Zen ED 2 appears to me to have as much stereo effect in its view as any porro.

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Sorry, it sounded that way to me when I read this comment:

"I don't get enough of a performance wow over the extra bit of 3-D from the porro. I realize others literally see things differently. This is an interesting question and I'm curious to see how the responses shake out."

To me, there's way more than an "extra bit of 3-D" when I compared the 8x32 SE and 8x32 HG. Night and day. Viewmaster vs. Flatland. Same with every other 8x30/32 roof I've compared to my SE or EII except the 8x32 EL, which had more 3-D effect than I've seen in any other midsized roof.

Full sized roofs are somewhat better, the 8x42 HG, for example, shows more 3-D effect than it's baby brother, but still not as much as my 8x32 SE, let alone the even wider spaced 8x50 Octarem.

I agree about the 7x36 ED2, but that's the exception not the rule, and you have to go down in magnification to get that extra depth. Most roofs I've tried in 8x and 10x show significantly less 3-D effect than comparable configuration porros. I assumed that if you couldn't see that, you were somewhat immune to the 3-D effect of porros. Wouldn't surprise me, some people can't see CA or RB or excessive pincushion or the "roof illusion" or field curvature or even astigmatism at the edges of the FL. As you said yourself, people see things differently.

But if I assumed wrong about the 3-D effect and made and "ass out of u and me," I apologize. (Got that one from the "Odd Couple"

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brocknroller said:

Sorry, it sounded that way to me when I read this comment:

"I don't get enough of a performance wow over the extra bit of 3-D from the porro. I realize others literally see things differently. This is an interesting question and I'm curious to see how the responses shake out."

To me, there's way more than an "extra bit of 3-D" when I compared the 8x32 SE and 8x32 HG. Night and day. Viewmaster vs. Flatland. Same with every other 8x30/32 roof I've compared to my SE or EII except the 8x32 EL, which had more 3-D effect than I've seen in any other midsized roof.

Full sized roofs are somewhat better, the 8x42 HG, for example, shows more 3-D effect than it's baby brother, but still not as much as my 8x32 SE, let alone the even wider spaced 8x50 Octarem.

I agree about the 7x36 ED2, but that's the exception not the rule, and you have to go down in magnification to get that extra depth. Most roofs I've tried in 8x and 10x show significantly less 3-D effect than comparable configuration porros. I assumed that if you couldn't see that, you were somewhat immune to the 3-D effect of porros. Wouldn't surprise me, some people can't see CA or RB or excessive pincushion or the "roof illusion" or field curvature or even astigmatism at the edges of the FL. As you said yourself, people see things differently.

But if I assumed wrong about the 3-D effect and made and "ass out of u and me," I apologize. (Got that one from the "Odd Couple"

<B>

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I think there is a difficulty many people have in realizing what they see through a binocular is (or may not be) typical. Not a complaint or a criticism, just an observation.

It is one of those "givens" or "things everybody knows" that porros have a better 3-D effect than a roof. After it gets written about enough, people to some extent see it, maybe even to a greater degree than it may actually exist, just because it's supposed to be there. But at the end of the day, it matters not. The eyes at the end of the oculars are the only ones that need to be impressed. Those eyes are different enough that almost any given set of eye balls can be an exception to any given "rule". I have always been agnostic about the wisdom of "conventional wisdom".

If you take the step down in magnification in a porro from 8x to 7x, the depth perception changes are far greater than what differences there are in the same step down in roofs. Get hold of a good pre action series Nikon 7x35 and you guys who like the E II so much might stand up and take notice. Many 7x35's will clean an 8x30's clock in the porro world. The depth of field and depth perception will go a long way in enhancement of the view.

Now, I agree that increases in magnification (at any level above our naturally occurring DNA 1X level) will compress the view, and that in certain circumstances and angles, magnification's tendency to compress thing can confuse some issues. Still, I see enough depth perception (3-D) with roofs, so maybe I am the exception to any given rule. As for the 7x36 ED2 being the exception, I think the exception is happening at the magnification level.

Assumptions are the bane of human nature (one of them anyway) so no apologies are necessary for any assumption.

I'd still like to know how focused, in phase, light beams that leave the last prism interface and pass in a straight line through the eyepiece to the eye, one from a porro, and one from a roof can contain different perception information. The only thing that comes to mind is that the final passage from the prism to the eye might be longer in the porro.

Steve C said:

I'd still like to know how focused, in phase, light beams that leave the last prism interface and pass in a straight line through the eyepiece to the eye, one from a porro, and one from a roof can contain different perception information. The only thing that comes to mind is that the final passage from the prism to the eye might be longer in the porro.

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The brain creates a 3D view from the information received from both eyes. Due to the separation between the eyes, the views are not quite the same i.e. there is parallax as mentioned by others earlier in the thread. So for example a near and a distant object might be inline when viewed from one eye, but not quite inline when viewed with the other eye. When using a binocular, the greater the separation between the objective, the greater the parallax.

A curious aside is that the brain uses the parallax to estimate how far away objects are, and hence how large they are. So the apparent size of an object viewed through a binocular changes according to the objective spacing. Interestingly a larger apparent size does not equate to better resolution. Apparently this has been known for a long time, but is rarely mentioned.

... I'd still like to know how focused, in phase, light beams that leave the last prism interface and pass in a straight line through the eyepiece to the eye, one from a porro, and one from a roof can contain different perception information. The only thing that comes to mind is that the final passage from the prism to the eye might be longer in the porro.

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Each barrel of the binoculars presents a slightly different view of the scene to its respective retina. Just as in normal vision, the brain fuses these images to create a 3-dimensional 'visual space.' The process is called stereopsis. With unaided vision we have learned to judge distances within this visual space, but those relationships change when binoculars are used, to a large extent because of visual compression (which is a monocular phenomenon). Note, that the use of binoculars largely eliminates peripheral vision (we only see what is contained in an approx. 8 deg. field.), and walking about with them isn't feasible. Greater retinal disparity (as with a Porro) might be of some assistance in relearning distance relationships with enough use, but switching between binoculars with different retinal disparities would almost certainly prevent it.

Ed

PS. Sorry Leif, I just saw your post. I agree with it all.