Stereo photography

[Xenedis]

Has anyone experimented with stereo photography?

Today I stumbled across the following image:

http://www.flickr.com/photos/ytf/5846267208

It's actually a pair of almost identical images, horizontally offset by a small amount.

The idea is to view the image from two or three feet away, and cross your eyes so that the two images appear as three. If you have the ability to throw your vision like this, within a few moments you'll see one image in 3D.

It's very cool -- to my eyes, at least.

I had heard of stereo photography, but never paid attention to it.

Now I am intrigued. I think I shall read up about it, and I might start experimenting with stereo photography if it's approachable.

[ricktas]

I have a 3D camera, and I can either do digital 3D or stereoscopic, must say I haven't tried the stereoscopic version, maybe I should.

[colinbm]

Hi Xenedis
Yes it is very addictive & simple if you have two identical Canon Point & Shoot cams.
Have a look here at SDM
http://stereo.jpn.org/eng/sdm/index.htm
This is an off-shoot of the CHDK group
http://chdk.wikia.com/wiki/CHDK

I have got two Canon A570IS cameras with identical firmware, & I have made them onto a frame to hold then together & the combined USB trigger etc
Unfortunately I am brain dead, & I haven't got around to getting them to working models :o
The SDM & CHDK groups are very interesting & is much, much more then it seems.
Cheers
Col

[Scotty72]

I saw a guy at the protest today with this sort of setup: two 5Ds set into a bracket and connected via a cable.

Very cool.

[Xenedis]

I'm curious as to what goes into producing the three-dimensional effect, and thought that maybe it could be achieved by juxtaposing slightly cropped versions of an existing image: one with a small amount cropped off the left side, and the other with the same small amount cropped off the right side.

While I was able to throw my vision, the true 3D effect wasn't apparent in the image.

There's obviously something more to it, and I clearly have some reading to do. :-)

[Scotty72]

Well, our eyes perceive depth by giving us slightly different versions of the same scene. Our brain then triangulates the image and then, depth.

Maybe it's the same principal..

Scotty

[Xenedis]

I gather stereo photography requires two cameras.

That might make it a bit difficult.

[Scotty72]

Expensive too :)

[colinbm]

It can be done with one cam. You will need to take one shot & very carefully move the cam by about 55-60mm sideways, but on the same plane & shoot again.
It is like closing one eye then, closing the other eye & you see two slightly different perspectives of the same view. One left, one right.
Col

[Scotty72]

But, u must be very precise: move it exactly sideways. Not a tiny bit up/down or forwards/backwards.

[colinbm]

I have heard of some guys doing a moon shoot with one on the east coast of America & one on the west coast & shooting the moon together at the same time, when the moon was half way across the American continent :th3:
Col

[mechawombat]

my original pentax optio 3.1mp P&S had this feature and I never used it

I feel the whole 3D thing gimmicky but great find Xenedis

[Xenedis]

It can be done with one cam. You will need to take one shot & very carefully move the cam by about 55-60mm sideways, but on the same plane & shoot again.
It is like closing one eye then, closing the other eye & you see two slightly different perspectives of the same view. One left, one right.

It sounds like the sort of technique that would require a dolly.

I wonder how the focal length (ie, ultra-wide vs. long telephoto) would affect the amount of parallel distance required between shots.

[colinbm]

If you look at the SDM site all will be revealed.
Close-up can be closer then the human eye space 55-60mm.
Further afield landscapes can be spaced wider.
Col

[ricktas]

The FUJI (http://www.fujifilm.com.au/products/digital.asp?id=77&sid=1&pid=1003) can take either HD 3D or stereoscopic photos if anyone is interested in getting into this. Or the older FUJI (http://www.fujifilm.com.au/products/digitalitem.asp?id=77&sid=1&pid=537) can take SD 3D. It is probably an easier way than buying two camera's and joining them together with tape etc.

[Mick B]

Here's one I did about 5 or 6 years ago.
With your eyes approx 12 inches from the screen, stare cross eyed at the black strip between the two photos. You might have to experiment with the distance until you can see a 3 dimensional picture which will appear in between the two
http://www.pbase.com/guzziev/image/50250904/original.jpg

[Scotty72]

Hmmm.

I kinda don't see the point of an image if you've got to stare cross-eyed at it. :rolleyes:

[Mick B]

Don't worry Scotty, I can't see the point either. That's why I only ever made 2 of these photos ! It's just interesting to see what can be made from a one dimensional image.

[ameerat42]

Yes. Posted a 2ple in an early thread or 2.

[mickyj]

I have personally played with Anaglyph images (Red/Blue Glasses required) and had not thought of this method.

The Anaglyph method has produced some very cool results for me.
http://www.flickr.com/photos/mickyj_photos/5657369562/

[ytf]

Such an interesting discussion: so interesting, in fact, that I have joined your forum in order to participate and perhaps answer some of your questions.
Thank you Xenedis for bringing my work to the attention of the forum.

As has been pointed out, the stereo photo is two separate photos taken several inches apart.(Yes, I'm American: I live in a world of inches, quarts, miles, etc.) I use a single Nikon D700 with older manual lenses. Since each photo needs to be as similar to it's mate as possible, auto-exposure and auto-focus can actually be a detriment. The benefit of a single camera is that the stereo base (distance between shots) can be easily varied depending on the subject matter. A general rule of thumb is a base 1/30th of the distance from the camera to the nearest foreground object. I don't actually measure, I just wing it. Some of the macro and pin-hole shots are only fractions of an inch apart. Others are as much as 40 or 50 feet. The result is a feeling of seeing the world as a Lilliputian in the former and as a Brobdingnagian in the latter. One also needs to take into account the focal length of the lens being used. I like a wide angle (my most used lens is a 20mm but I sometimes use a 200mm as well) which tends to require a wider base relative to distance than the longer lens. For instance, when shooting a cityscape from across the East River, my base is ideally about 35 feet. With the 200mm, however, I would shorten that to about 8 feet.

There are several cameras available which use 2 lenses and capture 2 images with a single snap. The greatest benefit to these cameras is that they can capture action. Me, I'm more of a still life kind of guy, so I have no real need for such a camera. A third option is a dual-camera rig. The most popular is made from a pair of Canon Point and Shoots using the CHDK hack to synchronize them. On could also use a pair of more advanced cameras, but the complexity rises exponentially when you consider that focal lengths of zoom lenses and focal planes need to match for each frame. The more complicated the rig, the more that can go wrong and fancy dual-camera rigs can get very pricey. I subscribe to the KISS principle (Keep It Simple, Stupid.) Since I shoot in a very crowded, fast moving environment, (New York City) I need to be able to shoot quickly and move on. Fiddling with gadgets is not an option.

There are a variety of viewing methods for stereo photography. The most traditional is parallel, in which the left-eye image is on the left and the right-eye image is on the right. I find this somewhat limiting in that most people (myself included) cannot freeview such an arrangement. A special viewer is needed and there is generally a limit to what sizes can be presented. An alternate and also rather traditional method is the red/cyan (anaglyph) method, long the staple of early "3D" movies. It is reasonably effective, but it tends to screw up the colours quite a bit. The third popular method is crossview. The left-eye image is placed on the right and the right-eye image on the left. The viewer crosses their eyes slightly until a single image with depth forms in the middle. This tends to be the most popular these days. It is rather simple to do, requires no special gadgets, larger sizes can be seen easily and the colours remain true. Note that no matter which viewing method is used, the photo can easily be changed to other styles. Most exhibitions are done using dual projection systems in which the images are mounted parallel.
Crossview is not nearly as difficult as it seems. Most people are quite capable of it and in fact do it constantly in their daily life without even realizing it. Try this: hold one finger up in front of your face. Without diverting your gaze from the finger, take not of things that are farther away. They will be double. Crossview is the same principle. With a bit of practice you can train your eyes to converge at a point closer to your face but focus on a point more distant. It is no more uncomfortable than if you were reading a book. If it feels uncomfortable, you're probably trying too hard.

One comment I read is that it seems like a gimmick. This is said about many things we accept in life. Painters have said that photography itself is a gimmick. Stereophotography is actually nearly as old as photography itself. In fact, Sir Charles Wheatstone presented the first treatise on binocular vision, describing the process of dual imagery, to the Royal Society in 1832. For those who know their photographic history, you will know that this was several years before the first photograph. The most widely accepted date for the first stereo photograph is about 1852. The first camera to use 35mm celluloid film was a stereo camera. In fact, stereophotography was widely used and accepted until the advent of Kodak's simple cameras made for use by the general public in the early decades of the last century. In order to reach the largest market, they kept it simple. (So much for KISS) Rather than partaking in a new gimmick, I consider myself upholding an old tradition. For the record, I'm not into 3D movies. I think I've only seen two in the last 30 years, and neither one was Avatar.

Feel free to browse my Flickr stream, www.flickr.com/photos/ytf. If you have any questions or comments, I would enjoy hearing them.

ytf

[ameerat42]

Xenidis. U don't need two cameras. For fairly static subjects just one will do. You shift it slightly between exposures. Keep the optical axes parallel between shots.
Am.

[Xenedis]

ytf,

Thanks for joining AP and offering your insight on stereo photography. I also enjoyed looking through your HDR stereo images last night.

I am keen to give it a try, but I have a single DSLR and no desire to purchase another camera.

I still have plenty of reading to do so I can determine the amount of distance I would need between frames.

I predominantly shoot seascapes, cityscapes and landscapes, and tend to rarely deviate from the 16mm focal length (full-frame).

What approach(es) do you use to keep the focal plane identical between shots?

[Scotty72]

I predominantly shoot seascapes...

Huh? Not for ages and ages... :p

[Xenedis]

]Keep the optical axes parallel between shots.

That may be the most challenging part.

[Xenedis]

Huh? Not for ages and ages... :p

Within the context of what's remotely relevant to the subject of this thread, what is your point?

[Scotty72]

Within the context of what's remotely relevant to the subject of this thread, what is your point?

We miss you :(

[ameerat42]

That may be the most challenging part.

Approximation will mostly do. Rule of thumb: the greater the subject distance the greater the separation between camera positions. Eg: if shooting a flower within about 1 metre, shift the camera no more than about 10cm. Make the centre of the 2nd image about 10cm away from that of the 1st.

Note though, that this advice is given with the "parallel viewing" method in mind. I' not sure what to say about the "cross-eyed" method.
Am.

[Xenedis]

Approximation will mostly do. Rule of thumb: the greater the subject distance the greater the separation between camera positions.

With a 16mm lens, it seems I'd need considerable distance between frames.

I'm more concerned about how to keep the focal plane consistent between frames, though. It's entirely conceivable that for the second shot, the tripod could end up 5-10cm further forward or backward than it was when the first shot was taken.


Note though, that this advice is given with the "parallel viewing" method in mind. I' not sure what to say about the "cross-eyed" method.


I used the "cross-eyed" method to view ytf's images, and it works quite well.

[ameerat42]

Xenidis. I have found that it does not matter about the focal length. Whether you had f=16 mm or f=160 mm, you'd still need to shift the camera about the same distance sideways, depending on your subject distance. Here's the rub, though: in wider-angle views you have lots more foreground to contend with. Sometimes you cannot match up both foreground and main subject in the same "3-d" view.

Now that I (vaguely) recall, the same "rule" holds for either method. (Just goes to show that it's not only hitch-hiking that gives the thumb a workout!)
Am.
Just thought about this PS: The Minimum camera separation you would tend to have is approx the distance between your eyes.

[ytf]

16mm on a full frame? I'm a bit green with envy. Seascapes are tough with a single camera since the water is always moving. Sometimes this can be worked out by using very long exposures (and a boatload of ND filters if its daytime.) As for keeping the axis parallel and the proper focal plane . . . practice. The focal plane is not usually a problem if you are a fair distance from the subject. It figures much more into the equation if you are taking extreme closeups or macros. As for the axis, I use several tricks. The first is that I have the grids turned on in the viewfinder. If there are objects in the way-far distance, I make sure that they line up to the grid in the same place for each shot. If I don't have that luxury, then I concentrate on the object that is centered and try to estimate the same distance on that part of the frame as the distance that I move between the shots. With digital, I can quickly toggle between the two after I've shot them to determine if I have done it well or not. I often re-shoot. Sometimes many times. With shots that are at strange angles which can be disorienting through the viewfinder, I sometimes just close my eyes and "let the force be with me." All of this is best learned with practice. Bear in mind, I have done thousands of these and have also tossed out thousands more because I wasn't satisfied with the alignment. It's always a bit heartbreaking to toss an otherwise beautiful shot because I muffed the stereo capture, but there's always other opportunities. (I'm the sort of guy who will work many hours on a shot, then decide I don't like it, toss it out and not look back. Just because I've spent countless hours on it doesn't necessarily mean it's good)

I mentioned in the earlier post that I vary my stereo base a bit depending on my focal length. ameerat42 has contended just the opposite. Technically, he's correct, but there are other factors involved as well. As he mentioned, with a longer lens (narrower field of view) there tends to be less foreground objects. But with a longer lens there is also a great deal of foreshortening. Stereo enthusiasts refer to this as "cardboarding." Sometimes altering the "correct" distance can help this out a bit. Sometimes not. As is often said, "they're not so much rules as they are guidelines." Finding the sweet spot takes practice and it's a style of photography best suited for the tenacious, rather than for those who are easily frustrated and disappointed.

There is a free-ware application called stereophotomaker that is useful for aligning the pairs. I have many years of photoshop experience, so I prefer that (and also because I do many other things to my shots besides align them for stereo) but SPM can be a very useful tool for those starting out.

ytf

[Bennymiata]

Back in the very late 50's or perhaps early 60's, my father had an Exacta SLR and he bought a Zeiss stereoscopic kit for it, which allowed the 35mm SLR to take 3D pictures by using an attachment on the front of the lens to take 2 half-frame 35mm photos on the one full frame.
Slide film was usually used, and the slides were made up exactly as per normal 35mm slides, then the slides were placed in a hand-held, back-lit and magnified viewer to see the photos.
The results were spectacular and it was very easy to do, except when the lab thought they were half frame photos and mounted them as such!
The distance between the 2 "lenses" was a bit longer than the distance between your eyes and it made the images seem more 3D than real life does.

I don't understand why they don't offer similar kits for our digital cameras today.
They could be done quite cheaply too.
You could just print out the 3D photos either on special paper, or just side by side and look a them in a viewer or 3D TV.
Nowadays, you can even get 3D pictures printed on lenticular paper so they look 3D without glasses or doing funny things to your eyes.
I believe there are a couple of these printers in OZ too, but don't ask me where.

Now I'm hankering after a Fuji 3D camera!
I shouldn't read this forum so often!

[ameerat42]

Benny. Soothe your urges. Try some of it. Who needs attachments, handy though they may be in some situations?
:)m.

[flame70]

I do this on a very regular basis to get a stereoscopic view of the retina so we can get a 3d view of retinal vessels and geography. i use a 40D back through a fundus lens and then offset the shots by a few millimetres. I then view the two images through a stereoscopic viewer to get the result.

[Duane Pipe]

Found this, It might give some ideas on how to make a bracket.
I hope this helps ;)


http://www.wikihow.com/Create-Stereo-Photographs

[ytf]

I don't understand why they don't offer similar kits for our digital cameras today.
They could be done quite cheaply too.


They do. It's called a Loreo Beamsplitter. It's fairly inexpensive, but like the Fuji camera, it's usefulness is limited.

[ameerat42]

Look @ this pic (http://www.redferret.net/?p=9779). You can see it's only a couple of inches between optical axes. OK for stuff to about, say, at a real stretch, maybe 10metres distant, on a good day.
Here's another (http://www.lhup.edu/~dsimanek/3d/stereo/3dgallery5.htm).

Also, I wonder how good they are optically?
Am.

[ytf]

Also, I wonder how good they are optically?
Am.

So-So. Since there are 2 reflective surfaces before the light reaches the lens, there are some strange anomalies. Also, they are fixed focal length and I think only 3 stops (sunny, partly cloudy and overcast.) Good for snapshots at a BBQ or a family outing at the zoo, but that's about it. The diagram in the second link is incorrect. There are two mirrors on the sides which reflect the light at a 90 degree angle toward the center and a prism in the center which directs it back toward the sensor.