Van Ekeren P43/41 Digital Twin

My experience with my crude  EZ200 Twin Rig made me a true believer in the convenience of digital stereo cameras. Despite the manual triggering of the two cameras, it was really a nice little set-up for casual snapshots. I never did get around to linking the two cameras electrically since the cameras only had 640 x 480 resolution. I did consider twinning a pair of Canon Digital Rebels, but the resulting rig would have been quite bulky and I would have had to orient the cameras vertically to avoid extreme hyperstereo lens spacing.I had several significant trips coming up in the Summer of 2005, including an Alaskan paddle-wheel cruise, and I really wanted a digital alternative to by 1950's -vintage Kodak cameras. My search for a practical digital stereo system ended when I first noticed the Sony digital twins on the 3-D Concepts web site! The particular camera that attracted my interest used an electrically linked pair of   Sony Cyber-Shot P41/43 cameras. One of these cameras, shown front and back, is illustrated below:

This camera has a true 4.1 MP CCD chip and, at its highest resolution/quality setting, creates pictures with 2272 x 1704 pixel resolution. Images are stored on Memory Stick media and a 16 Mb "stick" is included with each camera. At the highest resolution/quality setting, this is good for only 8 photographs, so you will definitely want to shop for higher capacity units. The camera features a USB 2 interface for fast downloads. What is nice about these cameras is how quickly they boot - power on to your first picture is just slightly over one-second. While the camera does have a nice auto-focus system, the focal length of the lens (33mm) is fixed (no optical zoom) and the 3X digital zoom is of marginal value. In terms of on-line reviews, the camera is highly rated by real people and tends to be brushed off as "merely a point-and-shoot" camera by those who tend to think that serious photography can only be done with expensive, feature-laden cameras.

The bottom-line is that any 50's-vintage stereo camera is basically a manual "point-and-shoot" camera. I was looking to replace the fuss and bother of film, not to mention the near-square image format, with a modern digital version that would not require that I take an exposure reading (or "guesstimate" the exposure) with each shot. The posturing of some self-promoting "experts" aside, the twin P43 system had some real potential.

Important Notes

(1) Although 3-D Concepts markets these cameras in the U.S., they are built in Jacob (Co) van Ekeren's shop in the Netherlands, with quoted delivery time in the 4-8 week range. Time for actual delivery was just a bit over three weeks. Co works steadily developing new camera combinations covering a range of performance specifications and cost. Even the 3-D Concepts website may not be completely up-to-date in terms of what is available. If you are seriously interested in one of these cameras, contact Jon Golden at the 3-D Concepts using the phone or e-mail contact information he has made available.

(2) David Starkman, a partner, along with Susan Pinsky, in Reel 3-D Enterprises, was an early user of the Twin P43 camera system. He wrote an article on his experiences with the camera which you can read, courtesy of David, by clicking on the link.

First Impressions

One of the most impressive aspects of the P41/43 series is that the build quality of the cameras is simply first-rate. The Ekeren twin configuration does nothing to diminish this aura of quality.

The cameras are individually mounted to pieces of 1/8-inch machined angle stock, unitized with a vertical plate that can be see in the rear view shown above. The MASTER camera is the right member of the pair and can be quickly identified by the fact that it is equipped with a hand-strap. The electronic cable slaving the two cameras is located behind the cameras and you have to look carefully to see it. The cameras are mounted to the angle pieces using their threaded tripod sockets using knurled machine screws set in slots. The sum of the slot length on both cameras represents the range in inter-ocular adjustment for the twin rig. the left camera is inverted with respect to the right one and the lower piece of angle stock contains a 1/4-20 threaded hole for tripod mounting if desired.

Basic Camera Performance

Resolution

In terms of image quality, the P43/41 is really a fine little camera. To provide for reasonable download times, I have tended to restrict images on this site to a display resolution of 640 x 480, with some variation dependent on aspect ration (i.e. Realist vs. full-frame formats). A full frame from the P43, reduced to this resolution, is shown below. For stereo display, I have opted for grayscale anaglyphs for simplicity. Many browsers use a high degree of image compression to speed the loading of images. This can introduce artifacts in images that degrade the stereo "look and feel". If you have a high-speed internet connection, try to disable graphics compression entirely to see the images at their best. You may have to tolerate some graphics compression if you have a dial-up connection, but please be aware that any artifacts you are seeing have nothing to do with the camera!

This particular picture was shot indoors, using available room lighting. To emphasize the detail that is lost in displaying the pictures at this resolution, the image below is a 640 x 480 full-resolution subset of the full-frame:

The stereo version of this image subset is shown below:

The inherent resolution of the cameras is entirely adequate for routine printing and Holmes-format stereoviews. As shown above, there is considerable latitude for full-resolution cropping for display at Internet-compatible resolution.

Flash

I was pleasantly surprised that the quality of flash pictures turned out to be quite adequate. The decorative mannequin shown below was the first image shot with the new camera while I was prowling around the house looking for suitable subjects.

Sensor Alignment

A digital camera differs from a film camera in that the physical structure of the case and position of the lenses is not the only factor impacting alignment of the image pairs. In a digital camera, the image sensor chip is subject to possible mis-alignment with respect to vertical and horizontal registration and with respect to differential rotation when comparing the two cameras that make up the stereo rig. When loading a pair of images for editing, it was immediately obvious that there was an obvious vertical offset between the right (red) and left (cyan) camera chips:

The measured offset turned out to be 18 pixels - about 1%. This is actually quite good, given the fact that the very tiny sensor chip has over 1700 vertical picture elements and the offset is easily corrected in the process of editing the stereo image.

Although not measured, I suspect there is a comparable or greater horizontal offset as well, as I have to crank in more horizontal displacement than expected to properly set the stereo window. This is not a problem, but does show that even well aligned digital cameras cannot be expected to yield perfectly aligned stereo pairs without some editing.

Rotational displacement between the two chips is harder to measure, but introduces serious editing problems if it is significant. I am not yet sure of the accuracy of my rotational error measurements, but any error does appear to be well under 1-degree and poses no issues so far in terms of stereo image alignment.
 
 

Synchronization

Many  erroneously assume that some sort of external hardware is required to obtain good synchronization when using digital cameras. In fact, if two P41/43 cameras are powered up at precisely the same time, they will start out in excellent sync, gradually drifting apart with time.

Here is a cropped segment from the background of one of my pictures that contained a decorative waterfall with many falling streams of water. The falling water streams are a bit soft due to the fact that the scene was shot with available light inside a conservatory, but there is absolutely no sign of disparate stereo elements that would indicate a lack of synchronization. The camera pair had been on for slightly over 5 minutes when this picture was taken. Given the normal power cycling to maximize battery life, synchronization should not be a practical issue with this twin rig.

So far I am quite pleased with the potential of the camera and I will certainly be adding material in the future. It is also safe to say that future galleries will be dominated by pictures shot with the twin P43 rig.

Ralph E. Taggart (taggart@msu.edu)