Talk:Stereoscopy/Archive 2

Article Structure
This article is about stereoscopy in general, as its title suggests, and it should not be structured so as to emphasize one particular aspect. Baseline selection is a very specific aspect of the subject, of one particular aspect of the article's subject, namely, stereophotography. stereophotography is just one aspect of stereoscopy.

John Elson (talk) 17:25, 24 August 2011 (UTC)

Most of the article is about stereo photography. It should be structured so most of the article can be understood. Stereo base is fundamental to many aspects of steroscopy so should be prominant in the article. While fixed base photographers dismiss stereo base geomnetry because they have no choice given the deficit in their cameras the geometry of stereo base is fundamental to understanding stereoscopy.

98.164.98.44 (talk) 20:30, 24 August 2011 (UTC)

This article is about stereoscopy in general, not just about stereo photography. The various viewing methods are far more appropriate than an in depth discussion of base selection. It could be successfully argued that it already takes up far too much of this article.

The key to continued and increased acceptance of stereo by the public at large is in finding easier and better ways to view stereo pictures. Most consumers of stereography don't care how it is produced. John Elson (talk) 03:58, 25 August 2011 (UTC)

''f you use that formula you would find that a picture of an object 20 feet away projected on a screen 20 feet away would require a stereo base of 2.5 inches. That's exactly the stereo base of a fixed base camera. You would also find from that formula that a picture of an object taken from 36 inches viewed on a monitor at 36 inches would require a stereo base of 2.5 inches. If you understand fixed base you at least recognize that.''

The advantage of understanding the formula is that it allows stereo pictures of objects farther than a fixed base camera can take for any given viewing distance. We don't have to fake it by including foreground objects or stereo window adjustments to conceal the fact that the distant object which may be the central subject of the picture isn't 3d. And we can recognize when it is being faked with foreground objects and window adjustments for the easy, consumer product fixed base.''

Nobody is disputing the fact that you can get more dramatic stereo with a wider base, and a variable base clearly better serves the goal of "geometric stereo." The point is that the purpose of wikipedia is to document a practice, not to advocate one view or another. Normal base stereography is the mainstream practice, currently and historically. It should, therefore, be featured prominently.

Your only justification for making "geometric stereo" more prominent is that it is your opinion that it is superior to orhto stereo. That is a serious violation of neutrality.

No matter what your reasons may be for thinking "geometric stereo" is superior to ortho stereo, it is not the mainstream practice, and that it the bottom line. The mainstream practice should be featured most prominently. John Elson (talk) 17:33, 25 August 2011 (UTC)

Moon Stereos
This technique can be applied to 3D imaging of the Moon: one picture is taken at moonrise, the other at moonset, as the face of the Moon is centered towards the center of the Earth and the diurnal rotation carries the photographer around the perimeter.

I put a tag on this because it seems very difficult to believe. The reason I say this is because there have been a number of stereo pictures of the moon and where the method is documented it has always been done using Libration, the slight wobbling of the moon on its axis relative to the earth. If it was as simple as taking pictures at moonrise and moonset then that would be the preferred method, rather than the far more difficult and involved method of using libration.

I suspect that the person who wrote that didn't know how moon stereos were taken and simply assumed that this is how it was done.

The first published stereo of the moon was in 1864, and it actually took 2 years to produce, one image was taken in 1862, the other in 1864. John Elson (talk) 07:55, 25 August 2011 (UTC)

Sorry but that is not true.Once again it stems from your ignorance of stereo base.

If the stereo image of the moon is viewed from 10 feet the geometry of stereo base calculates that the stereo base for the pictures is 4166 miles. Taking one picture at moon rise and one at moon set in most latitudes will work.

Just so any arbiter can see I'm using arithmatic not expressing an opinion or advocating a minority view. here is the formula and calculation,

Formula

(200,000 [miles to moon]/? [unknown miles stereo base]/(120 [inches distance to screen]/2.5 [inches seperation of eyes])

Carry out first order operations and form equation to solve for unknown stereo base;

200,000 [miles to moon]/48 = ? [unknown miles stereo base]

Carry out second order operation solving for stereo base.

4166 miles = stereo base.

98.164.98.44 (talk) 10:29, 25 August 2011 (UTC)

If that actually works, why would anyone bother with libration? What makes you think that there really is parallax between moonrise and moonset?John Elson (talk) 15:14, 25 August 2011 (UTC)

If that actually works? It's geometry. Basic Trig. Maybe your problem is that you don't understand the math.

A/(b/c)=D where A=distance to object, b=distance to viewing plane or screen, c=distance between eyes (2.5 inches) and D=stereo base.

A/(b/c)=D is 6th grade or high school trig. It's a simple ratio formula. If you knew trig or stereo base you would recognize this formula. You understand stereo base from the perspective of one who doesn't use it. You use fixed base.

If you use that formula you would find that a picture of an object 20 feet away projected on a screen 20 feet away would require a stereo base of 2.5 inches. That's exactly the stereo base of a fixed base camera. You would also find from that formula that a picture of an object taken from 36 inches viewed on a monitor at 36 inches would require a stereo base of 2.5 inches. If you understand fixed base you at least recognize that.

The advantage of understanding the formula is that it allows stereo pictures of objects farther than a fixed base camera can take for any given viewing distance. We don't have to fake it by including foreground objects or stereo window adjustments to conceal the fact that the distant object which may be the central subject of the picture isn't 3d. And we can recognize when it is being faked with foreground objects and window adjustments for the easy, consumer product fixed base. 98.164.98.44 (talk) 15:57, 25 August 2011 (UTC)

"difficult or uncomfortable to view without optical aids."
I'm talking about - "The side-by-side method is extremely simple to create, but it can be difficult or uncomfortable to view without optical aids."

Till date I've not seen any side by side image on a regular monitor which gives me a 3d feeling WITHOUT any kind of optical aid. But according to this line, it is possible but difficult. — Preceding unsigned comment added by 117.201.84.125 (talk) 11:10, 24 November 2011 (UTC)

It's possible, and not really difficult if you know how, but not everybody can do it. I have no problem viewing reasonably spaced normal pairs. But viewing reversed pairs where the right and left image are backwards is impossible for me. It requires looking crosseyed and I can't do that. Many people can do normal viewing but not reversed and vice-verse. Some can do both, some simply can't do either.

It did take me a while to learn and the learning method was somewhat novel. I found a book in the college library called "the Stereo Realist Manual" which had many printed pairs, sized for easy freevision. It also gave instructions on how to freeview. There was a small envelope in the back of the book that was supposed to contain a "lorgnette" viewer, but, of course, the viewer was long gone.

In the college bookstore I found something called a "stereoscope" which came with instructions. It was a folding metal stereoscope that turned out to be designed for stereo pairs much smaller than the ones in  the Stereo Realist Manual, such as those in a textbook used in a mineralogy class that was being taught at the time, and didn't have enough "prism" to fuse the images. Try as I might, I could not see the pictures in 3D. Then, after a little more effort I noticed that I was getting closer to fusing them and then, viola, I could see them in 3D! This led to endless hours going through the pairs in the book and reading the explanatory text. After a while, I found that, with a little effort, I could dispense with this device which was so illsuited to the task anyway.

In case you're wondering, this all happened in 1982. John Elson ★ 3Dham ★  WF6I A.P.O.I. 05:16, 26 November 2011 (UTC)

Edit war about Cross Eye Image
There is an edit war going on about a Cross Eye Image. Summary:
 * 09:58, 8 December 2011 - "Images are wrong way round - and I don't know how to reverse them." by
 * 08:13, 9 December 2011‎ - "Undid revision 464802768 by 109.153.242.10 (talk) Nope, if you show parallel it is normal and cross is backwards, just a s it would be" by
 * 08:33, 9 December 2011‎ - "Undid revision 464968382 by John Elson (talk)Rubbish: cross eye image should be right way round when viewed cross eyed - it isn't." by

Maybe some people here can help resolve this. D O N D E groovily  Talk to me  23:39, 9 December 2011 (UTC)

Perhaps an example should have been chosen which makes it easier for the less adept to tell which view view is correct and which is psuedo. When parallel viewed the parallel view looks normal and the crosseyed view looks inside out, just as it should!

John Elson ★ 3Dham ★  WF6I A.P.O.I. 04:52, 10 December 2011 (UTC)

The image was posted using Wikipedia's built in Stereo support, which I didn't know existed until today! The original image has normal orientation. Wikipedia shows the image as is when you select parallel and reverses right and left when you select crosseyed.

HOWEVER If you save the image to your computer you will get the original image only, not the reversed image, which is visible on the webpage! John Elson ★ 3Dham ★  WF6I A.P.O.I. 05:54, 13 December 2011 (UTC)


 * Ah! That would explain it.  I was trying to view the image on the image page itself, which (as now explained) didn't work.  The image in the article itself is too small to resolve cross eyed, so rather defeats the object of including it.  I didn't know about the built in stereo support either. 109.153.242.10 (talk) 14:54, 16 December 2011 (UTC)


 * I don't now what you mean at all by "too small". The images on the article page render roughly 4" wide on my laptop which is perfectly large enough for me to snap between parallel and crosseyed and back again at will.Tgm1024 (talk) 03:26, 17 January 2012 (UTC)

Digital stereo bases (baselines)
This information seems too specific for the general theme of this article, I believe it fits much better in the article about stereo cameras or in individual articles for the cameras listed. John Elson ★ 3Dham ★  WF6I A.P.O.I. 01:04, 6 March 2013 (UTC)

Wiggle Stereography
Searched for "wiggle" in the article, didn't find it. the reference should be there. And we could display a GIF image. 46.14.232.179 (talk) 10:46, 29 February 2012 (UTC)

Perscription glasses
Is there any kind of option for those of us with prescription glasses. Currently I have to wear the 3D glasses OVER my normal glasses. I like to watch 3D movies, and would be interested in "custom" glasses that allow me to watch, compensating for my prescription. Are there sources for this, and should there be a separate section?
 * See: http://www.avsforum.com/t/1367348/prescription-3d-glasses --Fluffystar (talk) 11:29, 4 July 2012 (UTC)

Those aren't really prescription 3D glasses, they are prescription glasses with a clip on for 3D, why not just buy a 3d clip on for $3 and use your existing glasses? John Elson ★ 3Dham ★  WF6I A.P.O.I. 01:15, 6 March 2013 (UTC)

Stereo Window
The explanation for window adjustment should not be written in a way that depends on the viewing method being used. Saying "move the right eye image to the right to move everything back " would be wrong for crosseyed mounting and saying "move the right eye image to the left to move everything back" would be correct for crosseyed viewing but wrong for every other viewing method, and would be confusing for the vast majority of readers.

An explanation that speaks of moving toward the center (or "together") to move forward or moving away from the center ("apart") to move backward works for all viewing methods and is less confusing to the vast majority of readers. John Alan Elson ★  WF6I A.P.O.I. 17:02, 3 November 2013 (UTC)

1950s 3-D chronology
I have just reverted a recent edit that generalized two mentions of the specific year 1953 to "the 1950s" and claimed in the edit summary that "there was nothing special about 1953".

As the 1950s recede ever farther into the fog of time, recent histories of 3-D (with the notable exception of works by a few dedicated scholarly researchers, e.g. Zone, Symmes and Furmanek) have been getting increasingly fuzzy about the decade's chronology. Sometimes they settle on 1952 and 1955 as preeminent red-letter dates because of the noteworthy but anomalous lone 3-D feature films released in the U.S. in those years. In fact those film releases are simply brackets around a 3-D fad that was largely confined to a single year.

Ignoring any activities behind the Iron Curtain, the only 1950s 3-D films screened for the public before 1953 were short films shown only at special events, such as the 1951 Festival of Britain, and the feature-length Bwana Devil, which premiered less than 40 days before 1952 passed into history and did not reach New York City and most other locales until early in 1953. In 1952 there were no anaglyph 3-D comic books, magazines, trading cards or jigsaw puzzles. In 1953 there were, along with dozens of 3-D feature films.

By early 1954 the initial broad public interest and enthusiasm had evaporated and most of the 3-D films released in that year were commonly if not exclusively shown "flat" in 2-D. By mid-1954 the last of the 3-D comic books and other anaglyphic stragglers still in the product pipeline had been disgorged, and to most people, in the U.S. at least, 3-D was already becoming a corny memory, last year's Big Thing, a fad that fizzled out. Although the newly-swollen ranks of amateur stereo photographers were generally not so fickle, they were still a very small minority of the population. I have no sales figures for the Stereo Realist camera, a durable good unlikely to need replacement, but I would gladly bet any number of dollars to dimes that a graph would show a spectacular rise and peak during 1953 followed by an obvious and perhaps nearly as precipitous decline.

In short, there was something special about 1953: it was the year of the big 3-D boom. AVarchaeologist (talk) 05:19, 16 November 2013 (UTC)

You could certainly argue that the 3D movie boom peaked in 1953 so that would make that year special in that sense, but it clearly began before 1953 and the way it is worded makes it sound like it was confined to a single year, which is utter nonsense! Bwana Devil came out in 1952 and the last Hollywood 3D movies of the 1950s came out in 1955.

It should also be noted that 5P "realist format" cameras were already available prior to 1953, most notably the Videon II in 1951 and the Revere in 1952. Also, the Kodak stereo camera didn't come out until the end of 1954 but during the 5 years it was on the market it outsold the Realist by substantial amount. In fact, during it's 5 year history there were 100,000 units of the Kodak Stereo camera aold vs 130,000 Stereo Realists sold in the 24 years between 1947 and 1971.

So you see, all 100,000 sales of the Kodak Stereo camera occurred more than a year after 3d movies peaked, and most were long after The last of the Hollywood 3D movies came out. The Stereo Realist Manual, often regarded as one of the best Stereo photography books ever published, didn't come out until 1955.

There were also a number of 5P and 7P cameras available in Europe before and after 1953. So it wasn't just A US phenomenon.

As the owner of thousands of stereo slides, I can assure you that many of them were taken before 1953, and a lot were take after that, so there doesn't seem to be any peak in the usage of stereo cameras in 1953. Indeed, it seems like more than just a stretch to suggest that the popularity of stereo cameras was part of something that happened in 1953. The popularity of 3D movies didn't seem to have anything to do with the 3D movie fad that peaked in 1953

You said yourself that stereo photographers were a very small minority of the population, so why would you think this had anything to do with a popular trend that peaked in 1953? John Alan Elson ★  WF6I A.P.O.I. 17:01, 16 November 2013 (UTC)

Since that statement is in a section about amateur stereo photography, statements about when the 1950s 3D movie boom began or peaked are of questionable relevance anyway. John Alan Elson ★  WF6I A.P.O.I. 18:07, 16 November 2013 (UTC)

" I would gladly bet any number of dollars to dimes that a graph would show a spectacular rise and peak during 1953 followed by an obvious and perhaps nearly as precipitous decline.

You would lose that bet. According to Realist insider Ron Zakowski, the peak year of production was 1954. Sales started to slip in 1955, due largely to the introduction of the Kodak stereo camera. John Alan Elson ★  WF6I A.P.O.I. 20:33, 16 November 2013 (UTC)


 * Was it the peak year of sales, too, or did it result in a glut of inventory that took a while to clear out?


 * To repeat: the 1950s 3-D film fad WAS largely confined to 1953. The lone 1952 and 1955 features and the mostly flat-shown 1954 releases (Creature from the Black Lagoon being the only important 1954 release widely shown in 3-D) are the exceptions that prove the rule. If you doubt, please contemplate some of the excellent research by Bob Furmanek now available online at 3Dfilmarchive.com, which IMO is of more value than all of the recent hastily cobbled together online and print histories on that topic combined. Refer also to the good books by Ray Zone and Daniel Symmes, both alas recently belated.


 * The movie fad is very relevant to stereo photography in general because it had a major impact on the extent of public interest in 3-D generally, just as the introduction of a number of digital 3-D still cameras in recent years is by no means unconnected with the leading phenomenon of a new wave of 3-D movies.


 * It is no news to me that stereo slides were being made long before and after 1953. I have a modest collection of stereo Autochrome color slides, some dating to circa 1910, as well as a sampling of 1950s and later Realist slides including a group that I shot myself in 1971.


 * How reliable are your sources for those sales figures on the Realist and Kodak cameras? As admitted above, I am no expert on that aspect of the subject and would be happy to cure my ignorance, but the numbers you quote above give rise to more than a little "cognitive dissonance": during several decades of contemplating the used equipment on offer at numerous camera stores and flea markets, I have seen many Realists but relatively few Kodaks. AVarchaeologist (talk) 21:13, 16 November 2013 (UTC)

You obviously haven't looked on eBay, look up "kodak stereo camera" and you'll get quite an education! As for production of Stereo Realist cameras, exact figures are not available but the approximate figures are as follows:

Before 1950  10,000 1950-1951    35,000 1952-1953     35,000 1854-1956     40,000 1957-1971      5,000

Note that there is no obvious peak in 1953 and the combined production for 1952-1953 was about the same as 1950-1951. The figures for 1954-1956 are lumped together, but according to Ron Zakowski most of these were made in 1954.

Note also that eight Stereo cameras hit the market in 1954 and about a dozen or so between 1955 and 1960. The amateur stereo photography market definitely didn't peak in 1953, the peak was in 1954 and the decline was much slower than for mass market 3D. Keep in mind the stereo cameras were expensive, even the Kodak sold for $84.50, that's $711.74 in 2012 dollars. The Realist cost almost twice as much and deluxe cameras such as the Realist Custom sold for over $200 ($1684.60 in 2012 dollars). So it isn't really surprising that the 1950s stereo camera boom did not closely track the mass market 3D boom which peaked in 1953.

In fact, considering that the stereo camera boom was already going full steam in 1952 and continued well past 1953, it seems that the two were not really that closely connected.

Your point about 1953 being the banner year for 3D movies and other mass market 3D is well taken, but the stereo camera boom did not peak in 1953, and there is really no reason why it should have. John Alan Elson ★  WF6I A.P.O.I. 22:59, 16 November 2013 (UTC)


 * Very interesting production statistics, for which thanks. They at least begin to give some definite form to the matter. But absent a year-by-year breakdown, and of sales rather than production, I am not paying off on any bets just yet. Scenarios can be hypothesized which would mesh with those stats (e.g., overproduction and warehousing in 1952, followed by underproduction, stock depletion and missed opportunity in 1953, leading to major overproduction and warehousing in 1954, creating a stockpile not depleted for years) yet allow for a significant sales boom, although not a "spectacular" one, during 1953. High cost of gear notwithstanding, it defies common sense that the introduction of tens of millions of people to 3-D as the fad blossomed in the spring would not have inevitably and promptly boosted sales of stereo cameras. But sometimes reality does defy common sense.


 * The post-1956 numbers are indeed shocking. Perhaps the more significant impact of the broader 3-D fad on amateur stereo photography is that when the fad crashed and burned 3-D was left branded as passé and rather silly: whipping out your Realist in public might attract intelligent questions in 1952, but it was more apt to elicit a condescending smile or open derision in 1957; not a healthy environment for the sale of either Realists or stereo Kodaks. AVarchaeologist (talk) 06:20, 17 November 2013 (UTC)

The point is that the Stereo camera boom was well underway by the end of 1952 and was not part of something that happened or peaked in 1953. This makes perfect sense if you think about it. People went to 3D movies and a smaller number read 3D comic books. They weren't looking at 3D slides. Most people who went to 3D movies had no idea that stereo slides even existed and you can't make 3D movies or comic books with a Realist.

You also need to keep in mind that most people didn't know how 3D movies worked, so the connection between 3D movies and amateur stereo slides wasn't nearly as obvious to them as it it to you and I today. In any case, the sharp decline in sales of Realists in 1955 was due largely to the introdcution of the Kodak Stereo camera at the end of 1954, which is why the Realist 45 was introduced in 1955 as a lower cost, easier to use alternative to the model 1041.

I guess the real point here is that the stereo camera "boom" is not part of something that peaked in 1953. It was going full steam by the beginning of 1952 and was still going strong well into 1955. John Alan Elson ★  WF6I A.P.O.I. 01:42, 18 November 2013 (UTC)

PEPAX/Telephoto distortion
My explanation for why this happens is at follows: If you take  a picture of same sized objects A and B  with A at 10 feet and B at 15 feet, the image of B will be  about 33% shorter (and 33% narrower). Usually depth clues and the stereo effect will tell you that one object is further away so they will both be perceived as being the same size. If you move so that A is at 40 feet and B is 45 feet, B will now be about 11% shorter. Again, this is what we are used to seeing so with no zoom or stereo base adjustment they still appear to be the same size.

If, however, we use a 4X zoom and multiply the base by 4, the relative depth of the scene is restored and A takes up about the same portion of the picture, but instead of being 33% shorter, B is only 11% shorter. This happens because everything is multiplied by 4 so the relative size of distant objects remains the same as it would be for the actual distance from which the picture is taken. Since the relative depth is restored, but the relative size isn't, B is now perceived as being larger than A even though they are actually the same size. This distortion becomes more apparent when zoom is increased and when the relative distance between objects is greater. In most cases, however, the effect will not be this extreme.

So, although this technique can be very useful, it does have limitations that require careful framing of pictures and selection of subjects.

Note that the same thing happens in flat pictures, but the depth achieved through pepax shows how far away the objects are relative to each other and so the distortion is more apparent.

I'm not sure we really need this explanation in the article, but perhaps a link to the article that discusses telephoto distortion will suffice. John Alan Elson ★  WF6I A.P.O.I. 01:54, 14 January 2014 (UTC)

Split
I also suggest to split Stereo photography techniques into a new article. The section is quite long and too detailed for a general article about stereoscopy. A new article would be easier to read, edit and maintain. --Fluffystar (talk) 19:25, 11 April 2014 (UTC)
 * Done. If there are any objections you could undo my edits. --Fluffystar (talk) 17:36, 12 April 2014 (UTC)

Merge with stereogram
I suggest to merge stereogram into this article. Stereograms are just all images of stereoscopy and everything is already or should be mentioned here. --Fluffystar (talk) 18:27, 11 April 2014 (UTC)
 * Done. I see no reason that suggest otherwise. --Fluffystar (talk) 17:57, 12 April 2014 (UTC)

Dichroic filters for projecting and viewing 3D
These have got good reviews in the UK Stereoscopic Society Journal ; The use of a plain white screen/surface is especially interesting. Time to include in this article? quota (talk) 14:26, 4 May 2016 (UTC)

Active Shutters "time parallax"
This is not true. "The main drawback of active shutters is that most 3D videos and movies were shot with simultaneous left and right views, so that it introduces a "time parallax" for anything side-moving: for instance, someone walking at 3.4 mph will be seen 20% too close or 25% too remote in the most current case of a 2x60 Hz projection." If the left and right images were taken sequentially then there would be a time parallax. The object will be in a different place when left image is taken that it is when the right image is taken so the eye sees this left right difference as further or closer than it should be. But when the images are taken simultaneously there is no "time parallax". The images are of the same moment. Even though the eyes see them alternately persistence of vision makes them appear simultaneous. If the cameras are not synchronized to be simultaneous and the object is moving fast enough there will be time parallax regardless of the presentation method, active shutter glass or passive anaglyph. 98.164.64.98 (talk) 10:52, 22 February 2019 (UTC)