Designing the perfect 3D Camera - Not so easy? (image copyright 3Ality Digital)

Manufacturers….double your Sales with a “3D ready” camera:

This article is for the Sales and Marketing Depts. of camera manufacturers, who either have not taken a proper 101 on stereoscopic 3D or are deliberately stalling the release of what could be perfect 3D cameras or camcorders. It is the hope that the Sales Departments come across this article and push for the release of such cameras that can be twinned for usage as both a 2D or 3D camera.

Although there is a mad rush by the electronic giants such as Sony, Panasonic, Samsung and the rest to capture a piece of the 3D market… one big thing that is lacking with them is a creative think tank in the Stereo 3D dept. How can we be sure of this? Take a look at the what is currently on the market for 3D capture.

Let’s examine some of the offerings, current D.I.Y 3D camera rigs and their shortcomings, and then put out a wish list or recommendations for improvement.

3D Camera from Panasonic - AG-3DA1

The All in One 3D Camera:

The current or first to market 3D Camera is from Panasonic called the AG-3DA1. This is a good camera, and does without the cumbersome beamsplitter that makes 3D cameras look like machinery from the 1970’s factories. It is lightweight, has two lenses and two sensors all in one compact unit. Convergence and parallax can be displayed on the LCD for 3D framing and there is even dedicated HDSDI outputs of both left and right videos for previewing purposes or for capturing to high bitrate Flash drives or external HD based recorders to overcome the AVCHD compression codec and bitrate.

Considerations: The price however may or may not appeal to the prosumer. As of July 2010, the price is said to be approx US$ 20,000/-  This is way more than most consumers/prosumers can afford, and if aimed at professionals, they will complain about the really tiny sensor size and the fact that the lens is “baked” in.

The other caveat of such an all in one camera is the fact that the Interaxial (distance between lenses) cannot be changed significantly for good “rounded” stereo 3D on mid distance subjects. Professional Stereographers play with interaxial a lot to capture good stereo in any given scene, while taking into account aesthetics, hyperstereo (miniaturizing) etc.

Also will the resolution and dynamic range be of acceptable quality in creating 3D movies for Cinema?

The BeamSplitter Rig

The BeamSplitter Rig:

The only option to use ANY Professional or prosumer camera on the market and get proper near-human eye spacing (interocular) with camera lenses (interaxial) is to shoot through a 2 way mirror or Beam Splitter. In this configuaration one camera shoots through an angled 2 way mirror and the other camera located at a 90degree angle above or below, records a reflection of the scene. This is the only way to adjust interaxial on cameras that are physically too bulky or have wide physical profiles that prevents them from having ideal or less than human eye separation. It is worth mentioning however, that only cameras that can be truly genlocked give perfect stereoscopic 3D sync.

Considerations: One of the biggest being the weight and limitation of maneuverability as can be imagined from the picture above. The other downsides are loss of light (f-stop) on one camera due to the mirror, thereby needing compensation and correction, also other problems to be overcome include polarization of light causing issues, dust on the mirror etc.

Side by Side 3D DSLR rig (image copyright Anachrome)

D.I.Y 3D video DSLR rigs:

Video DSLRs have what every professional Stereographer probably wants. Large sensors (usually a bad thing because of depth of field)…but when used creatively, can create amazing 3D. However due to physical profiles of these cameras, they either need to be mounted in a beamsplitter rig or inverted and placed side by side.

Considerations: With no genlock ports on these cameras, there will never be true sync. Some mis-informed stereographers and DoPs will argue that you can simply align the footage in post with an audio or visual cue. This is incorrect as most of these cameras use CMOS sensors that by their very nature “paint” an image one scan line at a time.

So while it may be possible to attain frame level sync between left and right images, it is almost impossible to ensure that both sensors are “scanning” each frame at the same time. Why is this important? Because in 3D this can give rise to temporal mis-match on any scene with moderate motion, such as hands waving, car wheels, even a person running will create motion artifacts. The suggestion to shoot at a higher frame rate does not guarantee absolute sync either. Some Sony and Canon cameras can have LANC ports and thus be Lanc controlled, a procedure that attempts to start both cameras remotely with a 3D Lanc controller, but sync does drift after a few minutes.

The other issue is finding a way to synchronize settings such as focus, metering and zoom if needed. There is no straightforward way to do so. In a configuration such as the one above, the interaxial is a also a compromise and close shots cannot be framed without resorting to zoom and/or H.I.T and cropping.

Loreo 3D lens for Single DSLR 3D (image copyright AnaChrome)

Single Lens 3D for Video DSLRs:

Two companies make 3D lenses that fit over camcorders and modern Video DSLRs. One such company is Loreo and now soon to be released is a 3D lens from Panasonic for it’s camcorders and the Lumix DSLR. These lenses seem ideal for an efficient and compact way to shoot 3D on a single camera.

Considerations: The lenses will only create “portrait” style framing as both left and right images are formed on a single frame. For example on an HD frame of video at 1920 x 1080, each half of 960×1080 will be shared equally between the left and right images formed. This is less than optimal framing for movies. Anachrome a company, ingeniously fits wide angle converter lenses over the 3D lens to widen the field of view, however this is still not full HD.

There may also be to a slight extent, temporal mis-sync due to CMOS sensor limitations, but it would not be as much as with two un-genlocked video DSLRs or a Digital camera pair with no way of syncing.

Changeable lens Camcorder Perfect for 3D? (image copyright Sony)

Is there such as thing as the Perfect 3D Camera?

The image above shows a new camera reported to be launched soon by SONY. It will have a large professional APSC sensor and interchangeable lenses. From looking at the slick profile of the camera, it can be seen how a pair of these cameras would fit nicely side-by-side to make an ideal 3D camera rig. By simply sliding the cameras apart, a large interaxial could be achieved. It looks like the perfect 3D Camcorder slated at a suggested price of USD 2000.

Further with built in HDMI output, it could potentially allow for live uncompressed capture of the video directly from the sensor, thereby overcoming any limitation of the AVCHD compression and built in chip storage.

So why is this not to be the perfect 3D camera…

Considerations and Caveats: From reading the specs of this camera, it can be seen for some strange reason that LANC control is not implemented! Even the cheaper camcorders from Sony offer LANC control, yet on this camera it has been (co-incidentally?) removed. It may be too much to ask for true genlock, but LANC being a Sony supported remote control protocol was the only other way to achieve at least some degree of sync.

The SALES and Marketing department of Sony are missing a golden opportunity to sell TWO of these cameras, by simply enabling an already established remote control system of Sonys. This is reason to believe that there is a missed opportunity here. Secondly if they had enabled true progressive scan rates, it would be what professional videographers and stereographers would really appreciate.

It is the sincere hope that this article will be a call to action to R&D and Marketing teams in Camera Manufacturing companies to take a look at the 3D revolution and get a share of it by going about it right.

The ideal 3D Camera or Camcorder could have at the very least:

• Some from of Sync control. At the least, LANC protocol and port or
• Genlock
• Unhindered and clean full HD preview via HDMI port (aimed at VideoDSLR manufacturers especially). This allows recording uncompressed video to external Flash drives or HDD.
• Slim physical profiles – So that two cameras can be placed side by side to yield approximate human eye spacing between the lenses of approx 2.5 inches.
• Changeable lens option would be perfect.

The RealFlex Secret – Do you really need a Beamsplitter Rig?:

At Real Vision, we have been producing content for Autostereoscopic 3D screens since 2004. Autostereoscopic (no glasses needed) screens, need between 8 to 9 cameras either CGI (easy) or real – not easy at all! to create content to be displayed on these screens. We had to overcome these obstacles and thus have been “reshaping 3D volume” or creating virtual in-between cameras with in-house tools.

This secret can now be adapted to conventional stereoscopy, and allow for shooting with a standard parallel 3D rig. The 3D volume can then be re-shaped in post using the RealFlex method.

Disclaimer: These are the independent views of the author only, and not meant as any direct criticism of any brand or manufacturer. All brands and copyrights respected. It is the intention of this article to stimulate thought in the 3D camera market.