In this section, we bring to you detailed methods and techniques related to sterephotography, from beginners and seasoned photographers alike. The aim is to share tips and notes on how to get started on specific methods. In other words, your personal DIY stereo guide.
written for the stereosite by David Kuntz (Rancho Palos Verdes, California, USA)
Stereo photography is a bit more demanding than traditional flat photography, because a poorly rendered 3D image can be difficult or unpleasant to view. So, the stereo photographer has to take additional steps, not required with flat photos, to avoid the problems that lead to viewer discomfort. The good news is that understanding a couple of relatively simple concepts will allow you to consistently produce 3D images that are easy to look at, and have good 3D impact. And, once you’ve absorbed these ideas, it won’t take you any time at all to routinely perform the actions necessary to accomplish this.
What is the Stereo Window?
The series of three photos shown here illustrate a key 3D photography concept that affects viewing comfort, namely, the stereo window. Imagine that your screen has a rectangular hole in it, and you’re viewing the 3D content in this image through it. That is, you’re seeing the boy pointing his finger at you through a window in your screen. The lattice of green lines in each image lies in the plane of your screen; in other words, your eyes see the green lines as being the same distance from you as your screen itself.
In the first 3D image pair (on top), the boy’s hand (which is the closest object in the composition to you), appears behind the green lines, or behind this window. In the next stereo pair (the middle), his finger has been moved closer, so that his fingertip is right at the plane of the window; the exact same distance from you as the green lines. In the last 3D image (bottom), his fingertip has now come through the window, and is closer to you than the green lattice of lines.
These three 3D images are all the same photo. So, how did this transformation in terms of their depth relationship to the stereo window (or plane of the screen) between them occur? The little red arrows between the photos indicate how it works. If you compare the position of the boy’s eyes in each of the left side images with the leftmost green vertical line, you can see that the entire image has been moved slightly to the right in each successive pair. The right side image doesn’t move at all. This is possible because the original photo has lots of additional material off the left and right edges that is being cropped off here.
This cropping, and how it relates to the window is shown again in the next two photos. Here, you can see this image is cropped down quite a bit (in other words, there’s lots more in the original image that’s not being shown outside the frame of the crop). But, by sliding the image left/right relative to cropping rectangle (or stereo window), the depth relationship of the subject matter with respect to the window is changed. What is not changed, however, is the depth relationship of elements within the composition itself (such as the perceived depth distance from the tip of the boy’s finger to the background). Those were set when the image was originally taken, and cannot be subsequently changed. All, that’s happening here is an adjustment in the relationship of the image content with respect to the frame it’s contained in.
Why worry about the Stereo Window?
The next series of photos is intended to demonstrate why you should care about the positioning of the stereo window relative to your photo. In the first one, the flower petals at the edge of the frame are in front of the stereo window. This causes a bit of visual confusion, especially at the left edge of the frame. There’s also some “shimmering” at the frame edges, because there’s so much image material that shows up at the edge of one image that doesn’t appear at the corresponding edge of the other image.
In the next photo, everything is far behind the stereo window. This again causes a bit of “shimmering” on the left and right sides of the image because so much of what appears at the edges doesn’t match up between the left and right. However, this version isn’t that unpleasant to view.
The third image has everything in the image set just behind the window. It’s comfortable to view, doesn’t have a lot of shimmering at the edges.
If the differences pointed out here aren’t obvious to you, don’t worry. Your sensitivity to how the window is adjusted depends on a few factors. First there are individual variations in how we each perceive stereo photos, and our tolerance for these adjustment factors. Next, the size of your display, and your distance from it, are also important factors. If you’re viewing this tutorial on a small phone screen, it’s quite possible that you either won’t see the differences between the last three photos, or won’t be bothered by them if you do. But, as display size goes up, these differences become much more noticeable and disturbing. When viewed on a large screen 3D TV, or if projected on a large screen, even much smaller differences than those illustrated here can produce a significant amount of viewing discomfort. The takeaway from this is that if you’re only showing your images on Instagram, you don’t need to worry about all this nearly as much as if you’re projecting them for a crowd.
How Do I Control the Stereo Window?
So, if you now understand the need to set the position of your subject matter with respect to the stereo window, the next question is how to accomplish that. That turns out to be the easy part.
Two of the applications that can be used to readily perform this adjustment are the Windows-based program StereoPhotoMaker, and the corresponding iPhone/Android app, 3DStereoid (both produced by Masuji Suto). No matter which program you use, the very first step you should take, before performing this window adjustment, is to “auto-align” your image. This gets rid of any vertical, rotational, perspective or other misalignments that can make a 3D image uncomfortable to view.
With auto-alignment complete, set the window in StereoPhoto Maker by going to the “Adjust” menu, and then selecting “Easy Adjustment.” This brings up a large dialog box with lots of options, along with your image displayed in anaglyph (red/cyan) format. To adjust the window, just use the slider at the top of the window (indicated in red). This allows you to move the two images horizontally relative to each other. As explained previously, this will change the relationship of your subject matter to the stereo window.
Another option in StereoPhoto Maker is to stay in the main program window, and then just use the left and right arrow keys to make this adjustment. Each press of the arrow key shifts the image a small amount, so it’s easier to use the Easy Adjustment menu if a large shift is needed in order to get the right window setting. This adjustment can be performed with your image displayed in virtually any format; anaglyph, parallel pair, cross-eye pair, and so on. So, you should probably choose a display method which you are actually able to view in 3D.
In the 3DStereoid app, this same functionality is available by selecting “Edit” from the main menu. Then, the left and right arrow buttons (indicated in yellow in the graphic) will shift the images relative to one another.
How do you know when you’ve got it right? Any part of your photo that doesn’t have a red or blue fringe (that is, the red and blue images are perfectly overlapped there) when viewed in anaglyph is right at the stereo window. This situation is illustrated in the next graphic, which shows that the right side of the rightmost flower in the image has no color fringing, and will therefore be exactly at the stereo window in terms of depth. The petal next to that does show a fringe, and won’t be at the window. It can be helpful to view your image through anaglyph (red/cyan) glasses during this process to visualize the relationship of subject material to stereo window, or alternately, in another format that you can actually view in stereo. Often, a final step of cropping your 3D image may be helpful after setting the window. This can be helpful to eliminate parts of your photo that don’t match up well or are visually distracting after windowing has been performed.
Hopefully, this tutorial has shown you the need for stereo window adjustment and it’s benefits, and given you a simple, easy to use method for performing that adjustment. The key takeaways to remember are:
- “Shoot loose.” That is, be aware when you’re taking your photo that you’ll probably end up losing some of it on top and bottom during auto-alignment, and on the left and/or right during windowing. So, purposefully include a bit more on all sides to accommodate this eventuality.
- The depth contained within your image is determined when you take it, and can never be changed. What you can change during subsequent adjustment is the relationship between you subject matter and the stereo window (the frame of the photo).
- Always perform an auto-alignment on your 3D image(s) first, before commencing any other processing operations.
- You’ll often want to perform a final cropping step after windowing an image to “clean it up.” That is, crop out anything that somehow got cut off by the process or doesn’t look right.
- Windowing can help make your photos easier to view, and should be done on every single 3D image you make. But, it becomes increasingly important as you go to larger displays. So, it’s not nearly as important for images intended for viewing on a small cellphone screen, but it’s absolutely critical for large screen projection. But, it’s easy to do, so why not get in the habit right now?
written for the stereosite by Gordon Au, USA
If you already take stereophotos using the sequential (‘cha-cha’) method with your phone or camera, you’re undoubtedly aware of its limitations: your main subject has to remain perfectly still; people and cars moving in the background create discrepancies; changing light between shots is a problem; windy days can be impossible. However, you may or may not know that adding a small handheld mirror to your stereo arsenal can help you overcome many of these problems. With the mirror reflecting half of the camera’s view, you can capture an entire stereopair in a single shot, eliminating timing-related issues. Though it depends on the mirror and camera(lens), this is usually best for close-up shots:
This figure shows the basic principle: the mirror reflects one half of the camera’s view (in blue) over to the opposite side, where it overlaps with the other half view (in yellow). For everything in the green overlap area, you get 2 different views—stereopair potential! Technically, a system that combines a mirror and lens like this is called catadioptric.
The trickiest part of taking catadioptric stereos is positioning and holding the mirror. The basic steps are:
- Bring the vertical mirror right up to the camera lens (but not touching it!).
- Move the mirror to the side, until the near edge is no longer visible to the camera.
- Tilt the far edge of the mirror back towards the center, until approximately half the camera view is reflected.
You can do this on either side — whichever is more comfortable.
The setup should look something like this:
And your raw picture will look like:
When you start out, you will need to fine-tune the mirror position and tilt. I recommend taking a series of test shots, using the same subject (at ~1–2 mirror lengths away), and with different combinations of mirror positions and tilts:
- Shot #1: mirror 0mm from lens edge / 40% of view reflected
- Shot #2: mirror 0mm from lens edge / 50% of view reflected
- Shot #3: mirror 0mm from lens edge / 60% of view reflected
- Shot #4: mirror 3mm from lens edge / 40% of view reflected
- Shot #5: mirror 3mm from lens edge / 50% of view reflected
- Shot #6: mirror 3mm from lens edge / 60% of view reflected
- Shot #7: mirror 6mm from lens edge / 40% of view reflected
- (And so on…)
To process the shots, simply:
- Straighten if necessary, so the mirror edge is perfectly vertical.
- Separate the two images.
- Un-reflect (horizontally flip) the mirror image.
- Edit the two images as you would for any stereopair.
I recommend using StereoPhoto Maker’s auto-align function
After processing, go back to your notes, and see which combination of mirror position and tilt worked the best. (What amount of depth do you prefer? Which stereopairs turn out the cleanest?) You might want to follow up with more test shots of subjects at different distances.
Beyond ‘getting started,’ there are further details worth discussing about mirror stereos, including the ideal mirror (size; shape; type: a front surface mirror (first surface mirror), which you can find on Ebay), precise processing (cropping, matching size and focus, correcting for keystone distortion), history and theory, and more. Learn about some of these in “DIY Catadioptric Stereos” a video tutorial I made for the National Stereoscopic Association’s 3D-Con 2020. Also, check out the corresponding gallery and see #catadioptricstereo on Instagram for example shots.
Feel free to send questions through my website WorldOfDepth.com, or via Instagram. Have fun experimenting, and I look forward to seeing your mirror stereos!
Gordon Au (New York, USA)
I am an avid stereographer and general 3D experimenter, making stereophotos, stereovideos, anaglyphs, extractions, and conversions, drawing upon a variety of sources, including TV and film, artwork, NASA data, product reviews, and more. I experiment with catadioptric stereos, asymmetric framing, video panning / zooming of 3D stills, x‑rays and fog as depth map sources, and more. I am a proud member of and have presented and/or written for the New York Stereoscopic Association, the National Stereoscopic Association, and the International Stereoscopic Union.
written for the stereosite by Graeme Barclay, Scotland
If you are already taking stereo pictures, well done! However, if you desire to broaden your horizons by capturing more challenging images, for example freezing motion, or creating dramatic landscapes, then a twin camera set up may be the answer.
Like many people I started in stereo photography with my cellular phone respectively one camera, taking sequential stereos. While this is adequate in many circumstances where there is no movement between the two frames, however it is limiting. For example, background movement, or water movement in rivers or the sea ruins stereo pictures taken using this method.
After three years of traditional photography and having the advantage of working alongside professional photographers, I soon realized I was looking to create high quality stereo images. To do this I required two cameras and a means to trigger them in sync. I also wanted the flexibility to have interchangeable lenses to enable a wide range of styles, which also provides the ability to add neutral density filters for long exposure photography.
So now I have twin cameras. Ideally, two cameras exactly the same would be the best plan, however, I have a Sony A6300 and a Sony A6400. These work well together. I mounted these together on a 30cm plate. Next, I needed to find a way to link them together. Sony does make a sync a cable to link these cameras, so triggering one camera automatically triggers the other. While this does work, I also needed to trigger the cameras remotely removing any chance of camera shake. It is also much more convenient to be able to trigger the cameras from a distance without any trailing cable.
I bought a wireless set up on Amazon as well as two additional cables. I cut off the original stereo jack plugs and soldered on an ordinary stereo jack cable I had. Connecting the third cable wasn’t as easy, as the colours of the wiring in this cable were different from the other two. I connected an old camera and started testing to see if this worked while keeping notes of the many failed attempts. I do not advise a trial and error of this type as it may damage your camera. It might be advisable to get cables of the same type so that the colours will probably match perfectly or to seek professional or advice from your camera manufacturer. At least, all this depends much from what cameras and what kind of remote control you include in the set up. So you might encounter something similar, hopefully you will not.
Finally, it all came together, and it was working! I could both focus with the half press and fire with the full press of the button. The electronic shutter release of this type is simple to use and has a positive distinction between focus and shutter release. Finally, this set up allows cable release as well as wireless release. Changing from cable to wireless could not be simpler. Removing the jack plug from the transmitter and connecting it to the receiver works perfectly. Instructions to pair the transmitter and receiver are provided and simple to follow.
Now that it is all connected, how could I make sure it was really synchronized? I opened my laptop, searched for a stop clock and let it run, focusing both cameras on the screen and firing them. My first few attempts showed there was 1/20th sec of difference between both cameras. For my approach, this was unacceptable. This was not only due to my using two different camera models. I began scrolling through each of the camera menus, mirroring every setting until I was successful. Both cameras were syncing perfectly on single frame and single focus. However, I still can’t get these to sync in continuous focus setting, silent mode or in a burst of more than one frame.
Mounting the cameras
Connecting L brackets to cameras is extremely beneficial as this makes it easier to switch from portrait to landscape very quickly. Shooting in landscape will provide more flexibility when it comes to aligning images, especially for novices. My personal preference is shooting in portrait. At the point of shooting I am always very careful with framing, so I do not crop much of the picture in editing.
My most recent addition for stereo astro photography is a 600cm base plate, allowing a far wider base where there is no close foreground to enhance the stereo effect. Enlarging the baseline is also beneficial for landscape photography.
Advantages of twins
Whilst the cellular phone in many instances will take good quality stereo pictures, which is adequate for social media or website galleries, there are many distinct advantages of having a twin stereo set up for simultaneous stereo photos.
- Manual control of shutter speed, aperture, ISO and focus
- Aperture or shutter priority or full manual
- Freezing motion
- Controlling the depth of field
- Much larger file sizes suitable for projection
- Shooting in RAW files, allowing deeper post editing
- Multiple lenses, from telephoto to super fisheye wide angle
- Able to use Neutral density filters enabling very long exposures
- Gradient filters for when the sky is too bright
- Connecting to an external flash
All that said, I am no way dismissing the unique flexibility of shooting stereo using the cellular phone. Its cameras are continuing to improve. Your phone is always with you. There are many apps for aligning and editing stereo images, the screen size allows for instant free-viewing, and posting on social media is extremely quick and easy.
Graeme Barclay (Edinburgh, Scotland)
At this point, I’ve been taking digital photographs for a little over three years and stereo photography for around six months. I’m employed within the financial sector but have had many years experience in hydraulic engineering and overcoming technical issues.