Detroit 2015 International Stereo Exhibition in our Ohio Stereo club. I saw a picture by Robert Bloomberg showing the Astronaut sculpture in Salt Lake City (see bottom for more details) and a small picture of the Earth was added in the upper right corner. I was there too (in SLC for the NSA 2015 convention) and took similar pictures. As a matter of fact, I entered a picture of the same sculpture in the same exhibition, but it was not accepted.
This gave me the idea so when I came home that night, I created this (click to enlarge if you need to):
Here is how I did it: First I found my Detroit entry. As I said, I took several pictures of this. I believe I took this particular one using my twin Panasonic LX5 cameras so it has quite a bit of depth. The sculpture is up high so it can be framed with the sky only in the background, or it can be framed with buildings. I tried to avoid the buildings to create the illusion of floating in space. I like this picture because it is “pure and simple”. Here it is:
I then found a picture (2d) of the moon that I took last month using my Questar 3.5 telescope and a Panasonic GX7 camera. The focal length of the Questar is 1350mm and my micro 4/3 camera has a half size sensor so the “full frame equivalent” focal length for this picture is a very long 2700mm, that’s why the moon spills a bit of out of the picture. This is fine because I wanted a big moon. Here it is:
Then I combined the two pictures using StereoPhoto Maker’s “add logo” function. This function is related to the “add text” function that allows you to add titles. The “add logo” function allows you to add a 3d logo to a stereo picture. However, it can be used to add a stereo picture into a stereo picture. Here are the steps involved:
1. Open the Astronaut stereo picture and save it in separate L and R images (“File”, “Save Left/Right images…”) This will be the logo.
2. Load the moon as a stereo pair (“File”, “Open Left/Right images” and then use the moon both times, so you end up with a flat stereo pair of the moon). This is the main picture that will serve as the background. Hit the Right arrow key to adjust the stereo window and push the moon a bit back (at what will be the infinity of the combined pair). I am aware that the moon could (maybe "should") be pushed even farther back but I am afraid the resulting image will have too much deviation. This issue would be alleviated if the astronaut pair had less deviation. Also, I could have used a 3d picture of the moon but this is not appropriate here when the moon is supposed to be far away.
3. Go to the “Edit”, “Add Logo” and work out the menu details to create the stereo pair you want. Here is how the menu that created my stereo image looks (hit enter to enlarge):
Regarding the details in this menu: I hit “Browse”, found my left Astronaut picture (from #1 above), the program loaded the stereo pair. I checked “Use Transparency” and with the color picker that came up I touched the blue background of this picture. I adjusted the sliding scale next to it (set to 6) and hit “Extract”. This eliminated the background from the “logo” picture. I adjusted the “size” of the logo so it fit well with the moon. I adjusted the “Depth” (set to 13) to make sure that the Astronaut is separated from the background and Image position (instead of typing numbers in these fields you can use the mouse cursor, hold the left button and move the image where you want to). And when I was done, I hit “OK”.
This involved a bit of trial and error. When you hit OK you go back to the program and can check your stereo pair (easy in my interlaced 3d monitor). If you do not like the results you can undo the Add Logo function (“Edit”, “Undo” or CTRL Z) and try again. The program remembers the last settings which is nice. Keep changing things until you get it just right.
I have used the “Add Logo” function before, so the entire process took less than 30 minutes. I think this is quite fast for a combined stereo image where a lot of variables (like sizes and relative depth of the two images might) need to be adjusted by trial and error.
One advantage of the Add Logo function: You can see any changes that you make while the Add Logo dialog is opened, in 3d. Click "Anaglyph" next to the Preview (right side). This includes things like changing size, changing image position, and (especially) changing depth.
Note: This was possible only because the background of my Astronaut picture (or whatever you select as “logo”) was uniform and could be extracted. If you have a more complicated picture then you have to use photoshop or perhaps Topaz Remask, a program that does exactly that, removes the background from an image. I have never used layers in photoshop and have not figured out how to use Remask, but I know how to use StereoPhoto Maker.
If you are interested in this sculpture, here is what I found in this source:
Michael Bingham returned to Flying Objects in 2014 with an equally ambitious creation entitled The Curious Voyager. Instead of an animal, Bingham chose an astronaut as the centerpiece for the sculpture—replete with a mirrored face mask—with the human space traveler floating upside down as he observes the streets of Salt Lake City below him.
“I’ll admit, I had just not too far back seen the movie Gravity and was really intrigued with that, with just the idea of weightlessness,” Bingham explained to the Herald Journal. “But that’s always been interesting to me. I’ve always been fascinated by astronauts.”
If you enlarge the picture you can see me and fellow 3d photographers reflected in the astronaut’s suit (helmet?). I was there with Ron Fross, John Bueche, Diego Ruiz (check the first picture below - this is what the dedicated photographer will do to get a different point of view), Peter, George Philosophos, Takashi Sekitani, and others. We were taking a tour of Salt Lake City on Wednesday of the convention week and the bus dropped us somewhere in the area. You could not miss this sculpture. I actually have a picture of all these guys photographing the same sculpture. By the way, Ron Fross won an award in the on-side stereo competition with one of his pictures of this sculpture. These are halves of stereo pairs:
Wednesday, October 7, 2015
Saturday, October 3, 2015
In the pantheon of stereoscopic viewers, I think this one deserves a special mention. This is a stereoscope that was created by John Dukes.
John writes (in the instructions): “This viewer grew out of my frustration with the disparity between what seemed to be magnificent photographs on some of my old viewcards, and the dismal system I had for viewing them. Having fought the battle to bring “ortho” viewing to View-Master slides, I wondered if it might be possible to view cards awe well.”
He continues: “Every cards I looked at seemed to be improved with lenses shorter than the roughly 200mm focal length system in most Holmes slide viewers. So I used 100mm (focal length) lenses and was astonished at the impact. And several of my cards seem to be so life-like that I wondered if maybe they were in fact photographed with 100mm lenses! But ALL of the cards were much more fun to view. I hope you will agree.”
John build his first Opticard around 2002. These were sold directly to stereo enthusiast by John and also through Jon Golden of 3D Concepts. I do not know how many viewers were made, probably around 50-100 (John told me around 50). They rarely show up for sale. In a photo-3d posting, Jon Golden mentioned that the last run of 20 viewers was ready for the 2004 NSA Convention.
What is so special about this stereoscope is that it does not use prismatic lenses. Now, prismatic lenses are required when you have stereoscopic images that are wider than the spacing of the eyes. John solved this problem by using achromatic lenses of very large diameter and short focal length. The large diameter takes care of the mismatch between eye separation and stereo pair separation. The short focal length produces large magnification to see all the details in the image. That's the summary.
Here are the specifications of the Dukes Opticard, from a posting from Jon Golden in photo-3d: The OPTICARD has high quality 50mm diameter, 100 mm focal length coated achromats. The optical stage has a 1.5cm interocular adjustment range, to accommodate even poorly mounted vintage view cards. A twin lead-screw mechanism, provides moderate individual focusing for each eye, and covers approximately + or - 1.5 diopters overall. A very bright, cool-running, built-in fluorescent diffuse light source, is carefully positioned to avoid distracting shiny reflections on the stereo viewcard surface. Estimated bulb lifetime: 6000 hours. Front-panel On/Off light switch. Machined aluminum components are anodized black, with a solid walnut front panel. 120V AC w/cord and two prong plug, Weight: 7lbs, Dimensions w/ handles: 12in. width x 10 in. height x 6in. depth.
And here is my personal experience (recorded through an ebay sales description – sorry if some points are repeated):
I bought this stereoscope around 2004. I know John Dukes personally and I admire his ingenuity and stereo skills. He has produced other amazing products too. I used the viewer for a couple of days, and then put it away. I did not touch it until a couple of years ago. I am not a big stereoview collector and do not make stereoviews of my own. So, back around 2008 I was going through the house, looking for things to sell. Since I have not used this viewer for 4 years, I pulled it out to sell it. I did a bit of research and found 2 units sold with the last year for about $800. I decided to test the viewer, and looked at some stereoviews that I was selling on ebay.
I WAS IMMEDIATELY BLOWN OUT OF THE WATER!!!
The amount of detail I could see was just astonishing! I have a couple of stereoviews showing stereo cameras or stereoscopic equipment, but I could not see much detail, even though I was using a top-of-the-line stereoscope with achromatic lenses. Everything was clear and right there with this viewer. I could see the MAXIMUM AMOUNT OF DETAILS! It was a pure joy!
My immediate thought was "I am not selling this treasure". There is no other stereoscope in the world that shows this amount of detail. Not only that, but the lenses' spacing is adjustable, so I can fuse all stereoviews (except for the totally-mismounted ones). Despite the very high magnification, this viewer is the most comfortable to use.
Why is this stereoscopic viewer so good?
The power of this viewer comes from the 100mm FL lenses which is about half the FL of standard stereoview lenses. Magnification ~ 1/FL, so the shorter the FL, the higher the magnification. I don't know of any other stereoscope with higher magnification (correct me if I am wrong).
The lenses are achromats. But, there is the trick: They are not prismatic. But how it is possible to view 3" (80mm) separated stereoviews with our only 65mm separated eyes, without using prismatic lenses? The answer is to have large enough lenses with adjustable interocular (distance). And this is exactly what we have here.
Look at the pictures. The lenses are held in a way that can be shifted, independently and by hand. Very primitive, but you know what, IT WORKS!
The two knobs that you see on each side of the lens board adjust the distance of the lens board to the stereoview, so they are used for focusing. Independent focusing at each side... that's new!
The light is provided by a fluorescent bulb. It is bright and diffused. The stereoview is inserted as seen and it just sits in place. The viewer is rather heavy, thanks to anodized (black) machined metal. The two handles are just great! They allow you to hold the viewer comfortably in your lap.
I was wondering... Since this is basically a simple viewer, does it have to be so large and so heavy? But it works surprisingly well. John Dukes has designed a no-nonsense devices, simple, yet solid and very effective. It does the job with flying colors.
How many of these were made?
I believe around 100. The serial number in the one pictured here is 145 (the numbering started at 100, not 1)... That's all for now. If I learn something new about this viewer, I will update the information here.
From all possible optical aberrations, chromatic aberration is perhaps the one that bothers me the most! Thankfully, a good stereo Realist format viewer (like my favorite, the Realist red button viewer) with achromatic lenses shows no chromatic aberration (except for the Kodaslide II, see my blog here). To check for chromatic aberration, just look through the viewer with no slide and pay attention to the edges. Do you see orange and blue colors? This is chromatic aberration.
Stereoscopes (for vintage 7 inch wide stereoviews) show chromatic aberration because they use prismatic lenses. Prisms (essentially asymmetric lenses) bend the light more than symmetric lenses and different colors tend to be separated more, hence the aberration shows up more easily. But still, not many people notice this, maybe because they do not know what to look for. But you should be able to tell when you use a stereoscope with achromatic lenses. One of them is the Keystone Visual Survey Telebinocular, used for eye testing in the early 1900s (maybe up to the 1960s or 70s?). These have different model numbers like this one, labeled 46C Ophthalmic Telebinocular:
I remember how I got my first Keystone Visual Survey stereoscope (pictured above). I recorded the story in a photo-3d posting: A friend from photo-3d offered to sell me this stereoscope for a little over $100, back in 2000 or earlier. I accepted but felt that I was doing him a favor and wasting my money because I already had some very nice stereoscopes at home. Perhaps I could sell it and break even, I thought. The stereoscope arrived; I opened the box and took a look. "Ugly duck" was my first thought. I decided to give it a try. Grabbed a few stereo views and took a look.
Wait!!! Just a minute!!! What is going on here??? There is something in the quality of the image that I have not seen before. Are my eyes being fooled? I ran to the basement and pulled out all my stereoscopes. I checked the same view with every stereoscope I owned, plus the Visual Survey. No, my eyes were not being fooled. The image through the VS looked better than anything else!!! No sign of chromatic aberration (I could see false colors in every other scope I tried). Sharper images. More details, especially at infinity. Easier for my eyes. I could be viewing for hours with no fatigue.
WOW! This baby is here to stay! I gave it a good TLC cleaning and have it in my basement ever since. Whenever I want to enjoy stereo views, this is the scope I use. Later, from discussions in photo-3d and input from Alan Lewis, I realized the secret behind the optical quality of this instrument: It has achromatic lenses! While every other scope has simple wedge lenses, this baby has achromatic lenses. I know from my slide viewer experience what difference achromatic lenses can make. The large size of the lenses and large FL makes this difference lens significant, but it is still there. And a trained eye can pick it up very easily.
Here is a comparison between the lenses of the Keystone VS Telebinocular, vs. a standard stereoscope:
The VS Telebinocular lenses are thicker (21mm vs. 7mm). If you take them out, it appears that these are halves of achromatic lenses. So, a standard stereoscope uses half of a standard one element lens, while an achromatic stereoscope uses half of an achromatic (two element) lens.
The bottom line: I sold all my other stereoscopes and kept this one.
But, it gets even better: Eventually, I bought a smaller stereoscope with achromatic lenses from Alan Lewis. It is called the “Achromat Lorgnette II”. It folds and can fit in my pocket. This is my preferred stereoscope, only because it is portable and I do not view stereoviews very often. Here it is:
A beautiful (made out of wood) portable achromatic stereoscope. I believe I paid around $300 for it in the early 2000s. Too bad it is not made any more.
There are many stereo Realist format slide viewers from the 1950s. The best ones have achromatic lenses. Some names: Stereo Realist, Kodaslide, Revere, Wollensak, TDC. Realist and Kodak made more that one model. For example, the Realist red button has achromatic lenses while the Realist white button has single element (glass lenses). The Kodaslide I has plastic lenses, the Kodaslide II has coated glass achromatic lenses (day and night difference).
Among these viewers, the question usually boils down this: Which viewer is better, the Realist red button viewer or the Kodaslide II viewer? This question would have raised a war in the 1990s (same as the question "which stereo camera is better, the Kodak or the Realist?") but I don't think anyone cares as much any more. But, in any case, I feel obligated to state my opinion.
I have seen, tested, repaired, all kinds of vintage viewers. The quality of the lenses is one factor, how well the viewer handles or works is another, when it comes to finding a personal favorite.
I have been very happy with Realist red button viewers. They have excellent lenses, metal rack and pinion and focusing. But they are fragile and they tend to break if your drop them. There is some variation in the optics. Some viewers show haze (loss of contrast) in various degrees, due to deterioration of the glue that holds the two elements together. If you find one with crystal clear lenses, then it is a joy to use and, in my opinion, the best vintage viewer ever made. This viewer can also be widened for 8p so you can view any image size you like. I offer this service, see: http://www.realistrepair.com/RBRepair.htm
[By the way, I repair all kinds of viewers so I am not trying to promote this viewer for this reason]
The Kodaslide II viewer has larger and coated "achromatic" lenses, which are, I am sorry to say this, some of the worse achromatic lenses ever put into a viewer. Just look through this viewer with a black and white slide or no slide just an empty mount, or nothing. You will notice: 1) Distortion (straight lines are bending, this is seen in all viewers but to a larger degree in this viewer), 2) Chromatic aberration (you will see colors at the edges, something that you normally do not see in achromatic lenses). Center sharpness is very good. The problems show at the edges and you can see them if you look at an empty slide mount (the image just confuses things so just look at an empty mount).
Now, I know that many people love this viewer and are not bothered (or cannot even see them) by these issues. Some claim that they do not exist. The fact is, these problems exist in every Kodaslide II viewer. I have tested hundreds of viewers and I can assure you that they are all the same, there is no individual variation. That's fine. The viewer has a nice friendly shape, the nose fits well, the larger size of the lenses is a plus, and used in AC it has a wonderful warm light. But the focusing sucks and the interocular adjustment and lens holders are all plastic and tend to break. Also, it cannot be widened as easily as the Realist viewer and certainly no wider than 7p (without a lot of difficulties).
In the end, it is all subjective. I had a good friend who loved the Brumberger viewer because it is simple to use, despite the fact that it has single element lenses. Another friend cannot tell the difference in quality between a Kodaslide I and II (to put it mildly, you have to be blind not to see the difference between these two viewers - the Kodaslide II has much better lenses, or, another way to put it, the Kodaslide I must have the worse lenses ever put into a stereo viewer).
The bottom line is that the best viewer is the one that you like the best. For me, this is the Realist red button viewer widened for 8p. Here is my favorite viewer:
Apertures widened to 8p, interior painted white, fitted with a halogen bulb. Through the years I acquired almost every stereo slide viewer ever made, including some very expensive custom-made viewers (by Ekeren and deWijs) but, in the end, this is the only viewer I kept.
For a different take on this, read this “Classic Stereo Viewer Shoot-out Results”: https://groups.yahoo.com/neo/groups/photo-3d/conversations/messages/103374 and feel free to form your own opinion.
I stand by my opinion:
The Realist red button viewer rules :)
The Realist red button viewer rules :)
In this blog I will describe three ways to measure the stereoscopic deviation in a stereo pair, using the free software StereoPhoto Maker. This is based on a Tutorial published in the Stereogram 20.2 (October 2015). Stereogram is the newsletter of the Ohio Stereo Photographic Society (OSPS) and it has been published since 1997. For subscription information, see www.ohio3d.com
What is Stereoscopic Deviation and Why Should I Care?
If you look at a stereo pair it consists of two seemingly identical pictures. However, the pictures are not identical, but have small differences in the form of displacements in the horizontal direction. It is these displacements (stereoscopic deviations) that are responsible for the sense of depth when the pictures are seen in stereo. So, yes, you should care :)
Here is a stereo pair. Notice that the house is displaced with respect to the tree. This is easier to see if the two images are superimposed:
Back in the good old slide film days, the only practical way to superimpose images was in stereo projection. Today, this is easy to do with digital images and programs like StereoPhoto Maker.
The deviations vary across the image (see the road in this picture), being zero at the “window” (tree in the figure above) and maximum at the furthest object (house). We are usually interested in the maximum stereoscopic deviation (P, I have used the letter P from "parallax" another term for this displacement). For an image to be viewed comfortably, this maximum stereoscopic deviation must be less than a certain amount, which depends on the viewing method. One popular recommendation for projection is to keep the maximum stereoscopic deviation under 3.3% or 1/30. Note that P has a value of length and it can be measured on film or a camera sensor or a display, so it depends on the image size, but it is more meaningful to divide this deviation by the image width to produce a ratio or %, which does not depend on image size.
So, now that we know what the stereoscopic deviation is, let's address the question, how can we measure it? But, first, let's load up an image to work with. I selected this stereo pair, a close-up of a butterfly. I took this picture during the 2010 NSA Convention. I would like to measure the maximum stereoscopic deviation and answer the question if this image will project well or cause problems. Here it is (in LRL format, click to enlarge and freeview):
But where is the far point in this image (which is responsible for the maximum stereoscopic deviation)? It seems to be in the lower part of the purse. There is black spot there which is easy to see (and measure). I will consider that to be the far point whose deviation I would like to measure.
1. Using SPM’s Auto Alignment report
After auto alignment with SPM, a window pops up with “Auto alignment values.” Look for the value reported as “disparity of the infinity points” near the bottom. This is reported as a ratio and in this case it is 1/18. This is about twice as large as the recommended 1/30 value. This serves as a warning that there will be excessive deviation in stereo projection. Here is how the report looks. I have circled the disparity value:
2. Using a grid in SPM
Dennis Green (of the Detroit Stereo Club) made me aware of this method. First, go to anaglyph (or interlaced) mode to overlap the two images. Then go to View -> Grid Setting (bottom of the menu, see the figure below). Set the V Line to 29 (this will divide the image to 30 segments). With just one look you can see which points are within one segment so have the maximum recommended deviation (1/30) or less. For the maximum deviation (shown below) this method gives a value of 2.5 times the recommended value (2.5/30 = 1/12).
3. Using SPM’s Position Alignment X value
At the bottom center of the SPM screen you see this: Position Alignment (x=0, y=0). If you press the R or L arrow keys, the x value changes (pressing the top and bottom arrows changes the y value). So my procedure for measuring deviation is this: Overlap the images (I like to use interlaced because I have an interlaced 3d monitor). Here is what I see. I have highlighted the far points that I will overlap to measure their deviation:
Use the R/L arrow keys to overlap two objects. Read the x displacement. This is the stereoscopic deviation in pixels. Here is what I get:
Divide this by the width of the image to get the % deviation. Using this method I measured 84 pixels for the far points. 84/936 (image width) = 9% or 1/11, which is close to Dennis’ grid method.
Note: the default displacement is 4 pixels every time you press the arrow keys, but this can be changed to a different value through the “Preference” menu shown here (to get to this menu go: Edit, Preferences, Adjustment).
Changing it to 1 pixel will give you the best possible accuracy. This value will also affect how fast the stereo window changes every time you press the arrows, so you might want to bring it back to the default 4 if you have changed it to 1 (4 works well, 1 is a bit too slow).
Note added later: Pierre Meindre mentioned in photo-3d that if you hold the shift key while pressing the arrows, the adjustment is made in 1 pixels increments, no matter what the default is. In this case, there is really little need to lower the default. As a matter of fact, Pierre increased the default to 10 for fast adjustments and then presses the shift key for fine adjustments. The default value of 4 works for me so it is good to know that I do not have to change this, just remember to hold the shift key when I want fine adjustments. (PS. I have now increased the default, like Pierre has done. This works the best for me. The window moves quickly and when I want to slow it down, I press the shift key.)
One last "trick" when using the Position Alignment method: If you press the Home key, the X and Y values are initialized (set to zero). You can also use this method to measure Y displacements (there should not be any Y displacements in a perfectly aligned image, but they often are because alignment is not or cannot be perfect).
Comparing the Three Methods
Notice that the SPM alignment report gives a smaller deviation than the other two methods. Using the grid or displacement method is more accurate because it is targeted to specific points. The report is based on image alignment which selects a certain number of points used in the alignment. The far point might have been missed (better: "not included") in the alignment. So the alignment report is good for giving you one quick value for the maximum deviation. If you are using auto alignment, you get this value with no extra effort.
The grid allows you to estimate the stereoscopic deviation in the entire image with one glance.
The Position Alignment method allows you to accurately measure the stereoscopic deviation for specific pairs in the image. It is the most accurate but also most time consuming.
Does the Excessive Deviation Matter?
This is a very good question. The fact that the maximum deviation is excessive does not mean that the image will have a problem in projection. It depends on how prominent the “offending” (showing excessive deviation) part of the images is.
In this particular image it is just a spot on the purse. One could use photo editing to remove this spot. The attention of the viewer is focused on the butterfly and the hand. The purse is mostly irrelevant and does not draw much attention. In that respect, this image works, even though it has about 3x the recommended maximum deviation. But if the background is prominent and cannot be ignored, then excessive deviation will be a problem. Knowing the maximum stereoscopic deviation is not enough to decide if an image will work or not. You need to see the entire image and make a subjective call. No matter if the deviation is a problem or not, knowing how to measure it can be useful.
One last comment: I think this image demonstrates the difficulty in taking a close-up of a small object with the Fuji with B = 75mm. A different camera (Panasonic 3D1 with B = 30mm) or a Cyclopital close-up attachment with the Fuji (B = 30mm) would have been a better tool for this particular picture.
Let me know if you have any comments and make sure that you check my other blogs for 3d stereoscopic information.