A modest proposal for 3-D projection

The efficacy of the stereoscopic cinema has been repeatedly questioned in the press in recent months. Those who follow the industry perceive that there has been a falloff in the stereoscopic portion of the revenue generating capability of recent feature films in North America. Various reasons have been given for this phenomenon, including poor quality conversion from 2-D to 3-D, poor quality films, and dim projection. I’m going to address the current projection situation with ideas for improvements. One thing to keep in mind is that most movies that get released don’t pay back their return on investment so why should 3-D movies be any different?

Questioning conversion quality is legitimate and there are both good and bad examples of the art. Similarly live-action 3-D cinematography quality is variable. The highest 3-D image quality is associated with CG animation.

It is generally accepted, by the press and by people in the industry, that stereoscopic projection is dim. I have several suggestions for how to go about improving projection brightness. Some of these suggestions will be perceived to be impractical. None of them would break the bank for exhibitors with existing installations. If only some of the suggestions are implemented alone or in combination we could more than double  the brightness of projected 3-D images.

It is a hellish tradeoff to ask people to accept a dim image that’s in 3-D over a bright image in 2-D. Few in their right mind would pick the 3-D image given this choice but that’s what theater-goers are being asked to accept.

The SMPTE standard for 2-D projection is 14 fL. (A special photometer aimed at the center of the screen when projecting clear leader for 35mm or a white field for digital should read 14 fL. to meet spec. ) The reason that we are accepting less brightness for 3-D projection is because it’s not easy to accomplish. But it’s not impossible. If 3-D movies were projected at 14 fL they would look great. I should point out that most of the time 2-D movies are probably not projected at the 14 fL standard but I surmise that it is pretty rare for the image to be in the realm of 3-D stygian gloom. The informal 4.5 fL goal for 3-D projection is a sad comment on the state of the art. If exhibitors want to give people a special experience that justifies the up-charge they need to have bright 3-D projection. Here are my suggestions for accomplishing that:

Screen size
Screen size has greatly increased over the years. I can’t prove it but I think it has doubled in the past half century. This is not the place to discuss the historical factors for this but is not uncommon for the front wall of theaters in a multiplex to be mostly screen even in a relatively small house. But a screen that is only slightly smaller can result in a great increase in brightness. Changing from a 40 foot wide screen to a 30 foot wide screen or from a 55 foot wide screen to a 40 foot wide screen will double brightness — all things being equal. Brightness is a function of area and a relatively small reduction in width can result in a large increase in brightness. The simplest and least expensive way for exhibitors to increase the brightness of stereoscopic movies is to reduce the size of the screen. This will seem like heresy to some of those who operate theaters but it’s a smart way to solve the problem. The audience will notice that the image is brighter but I think they won’t care that the image is a bit smaller.

Stop the detestable practice of running the lamp past its rated life. It still gives off light but its output falls of drastically with time of operation.

High gain screens
Exhibitors who’ve purchased Dolby or XPand systems, which don’t depend on polarization conserving screen which are also high gain screens, should not elect to stay with matt screens. They also need a high gain screen. They don’t need a silver screen but there are nonmetallic high gain screens that can increase the brightness by a significant factor compared to matt, something like 1.8 times. Even small theaters will greatly profit from such screens.

Projector choice
I’m now going to make myself an enemy of cost-conscious exhibitors all over the world. If you’re equipping a new theater for projecting stereoscopic movies get the brightest projector even for a small screen. I don’t mean the brightest projector for your screen size; I mean the brightest projector – which is also the costliest. I’ve been to too many theaters and screening rooms with small screens that are projecting dark 3-D images. You can’t spec the projector for 2-D and expect it to work for 3-D.

Scope projection
For 35mm scope is projected using an anamorphic lens. But scope in most digital cinemas is accomplished by means of cropping to get the wider aspect ratio. Cropping results in less utilization of the image engine and less brightness. My suggestion is that when projecting 3-D in scope exhibitors should use and an anamorphic lens to get the brightest image. This will be true for both top masking and side masking theaters.

To recap
I’ve given a number of suggestions for how the industry can improve the brightness of stereoscopic projection.
For a theater running Dolby or XPand products reducing the screen size and using a high gain screen could increase screen brightness by a factor of four. Polarization image selection systems like those offered by the MasterImage or the potentially very bright RealD XL system could also increase their brightness by the means described here. The RealD XL system can be very bright but practically it won’t be if it’s used in conjunction with a projector that is underpowered for that room, or with a screen that is too big, or with lamps that are run past their rated life.

Except for my suggestion for new theaters that they buy the brightest most costly projectors, every other suggestion could be accomplished for a relatively minimum outlay. The single most effective thing that an exhibitor can do is to project on a smaller screen and that would involve getting masking for the existing screen and possibly a new longer-throw lens. This could immediately double the brightness of projection. The other suggestions, such as getting a high gain screen won’t break the bank either. If only some of these suggestions are adopted by theater operators then in a matter of days we progress  from having a bleak stereoscopic cinema to one that is bright enough to justify calling 3-D movies a special event.


One Response to “A modest proposal for 3-D projection”

  1. robengle Says:

    Spot on as usual Lenny! I’d rather see a moderately smaller screen than one that is dark. I’m tired of seeing the films I’ve worked on so poorly presented.

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