24P High-Definition Image Aquistition
By Ken Garff, Director of Photography

Sony 24P "Cine Alta" on a Discovery Networks spot

I have always loved the graphic and artistic nature of photography. I grew up helping my parents develop and print black and white photos in our makeshift home darkroom. Until recently, I was certain that my love and understanding of the photochemical imaging process would be the base of my entire career. Then in 1998, a project I made for PBS was finished on the first 24p high definition post-production system. The image quality of the 35mm film mastered on 24p high definition was truly breathtaking. Over a few short years since then, HD technology has made leaps forward and rapidly gained momentum. Today the highend 24p digital cinema cameras can truly rival 35mm film imaging. Recent films like Attack of the Clones, and Spy Kids II witness that the era of digital cinema is now gaining momentum and there will be no going back because the technology is only getting better.

In the new realm of electronic cinematography, the Sony HDW-F900 "Cine-Alta," has quickly become the industry standard. Panavision, George Lucas, and a full range of high-profile motion picture, commercial and television productions have embraced the Cine-Alta.

I have prepared this overview in order to help clarify the advantages of shooting in 24p and provide information for those familiar with film production but moving toward digital as a possible alternative. In general, there are two main HD camera resolutions in pixels, Sony 1920 x 1080 and Panasonic 1280 x 720.

"1080" represents HD systems with a resolution of 1920 x 1080. With the advent of 24 frame-per-second progressive scan, "1080" can now be either "1080-p" or "1080-i." The "P" in "24p" stands for progressively scanned frames much like those acquired using a film camera. The "i" in "1080-i" stands for interlace. Interlace formats create a "frame" in two parts, all the even video lines known as a field, and then all the odd lines interweaving them to make a single frame. NTSC is an interlace video systems. "1080-i" is sometimes referred to as "60-i" representing the 60 interlaced fields-per-second since two fields make a single frame, you can see that we arrive at video’s 30 fps. It is the 60 fields-per-second that is responsible for the video look as it is often associated with soap operas, sports programming and news. On the other hand, progressive scanning in combination with high-resolution CCD imagers, and a film-like 24 frame-per-second frame rate makes this new technology very appealing for producers and directors used to shooting on film.
• 1. The Sony HDW-F900 “Cine-Alta” HDCAM is multi-format and capable of the following frame-rates and image scanning formats.

23.98p is the actual speed for most film or 24p applications. This is due to sound sync and compatibility with our current television systems. 23.98p is 24P for all intensive purposes.

Having various frame rates in the camera is a huge advantage. By using these frame rates it is possible to shoot high resolution slow motion in that will approach the look of 30, 50, or 60 fps in film by shooting at those speeds and playing back the tape at slower frame rate of 24 or 30 fps. (See the slow motion section below for more detailed information)

If your final product will be on Standard Definition video, then editing of dissolves, CGI, slow-motion effects and titling can all be done as usual with a “down-converted” Standard Definition master. The transfers can be made to Digital Betacam, Betacam SP, DVCAM or any other tape format. If you are finishing in NTSC then these tapes become your edit masters. The original HD tape can then be archived, like a film negative would have been. Having the original on 24p HD can protect you investment and not limit the repurposing of your content. Possible future uses of the HD camera master include making a HD version of the project, 35mm film print or other uses like pulling production stills, reframing shots, etc.

• 2. If the final product is to be released in HD or on 35mm film, then the EDL from your cut can be used to online a final HD master. HD online is becoming more readily available with both tape-to-tape and nonlinear options expanding rapidly. Avid Technologies has introduced an uncompressed 24p HD nonlinear system and Final Cut Pro 3 supports 24p HD with the addition of a special card available from Aja or Pinnacle. Cinema Tools is a new $1000 software program by Apple that will facilitate cutting in 24 fps on simple Final Cut Pro DV systems.

When it comes to actual media costs, 24p HD boasts an average savings of 98% over 35mm film. The average cost of one 50-minute HDCAM tape is $75. When recording 24P these tapes last longer than indicated on the box. A 40-minute Sony BCD-40HD cassette will last 50 min. These cassettes look very similar to Sony’s other professional 1/2' format cassettes like Digital Beta.

Approximated material and processing costs for 50 min. of
35mm film: $8600

Approximated material and processing costs for 50 min. of
24P HDCAM: $205

• 3. Basically, the same number of crew in every department is necessary to achieve the level of quality you are familiar with. The camera department can do without a film loader and can possibly gain an HD engineer under some circumstances. The “Cine-Alta” camera shooting at 24P is basically tungsten balanced with a rating of 320 ASA. Lighting packages will be identical to a film project using 320 ASA film. If you choose to shoot 60i then the camera will be rated at about 500 ASA. Effects of improper exposure in HD are more pronounced in the highlights. The F-900 camera has about 7.5 stops of latitude while film has about 10. Unlike film it is better to under-expose HD rather than over-expose.

• 4. Rental rates for HD camera packages will generally be slightly higher than film packages. The savings are realized in other ways outlined below;

32" client HD plasma monitor masked for 4:3
- No film stock costs
- No processing, prep or cleaning of film
- No shipping hazards or special transportation costs
- No waiting for dailies
- No dirt on the image or hairs in the gate
- No need for separate sound recording device
- No financial pressure when camera rolls
- Actors, directors more at ease
- No costly telecine for dailies or video masters
- No sound syncing in post
- What you see is what we get
- Instant playback in full resolution
- Less time spent reloading cameras

HDCAM is less expensive to shoot. Miramax has embraced 24p and claims a 20-30% reduction in production costs on films like Spy Kids II. Some expenses on the back-end must be planned for if a 35mm film print is to be made. A feature length film may cost $30-80K to output to 35mm film. This can still be less expensive than traditional film color timing, printing and negative cutting. It is also possible to shoot 2.35:1 wide screen and make the film prints in the anamorphic “scope” format. This digital-tofilm process also eliminates 2 generations of resolution loss because multiple masters can be output from the digital master so that printing can be done right from an original instead of an inter-negative.

Another benefit of 24p is that the production audio is recorded in the camera. Production can record up to 4 channels of 48Khz digital audio at 20 bits. This fidelity surpasses most DAT recorders. Other recording devices can also be used, however, the main production sound should be recorded in camera. External devices should be running time-code at 29.97 NDF, or 23.98 NDF.

• 5. The electronic shutter in an HD camera is capable of many more “shutter angles” than even the most advanced film camera. The base exposure time for 24 fps 35mm film and 24p is 1/48th of a second. In a film camera a spinning disc with 180° shutter opening achieves this 1/48th exposure. An electronic HD shutter can be set very accurately from 1/24th to 1/7000th. This is similar to 360° (no shutter) all the way down to .05° – both impossible in film cameras. This means that any effect that was achieved with shutter effect in film can be done in HD – from enhanced motion blur to staccato effect. The 360° or 1/24 feature increases apparent motion-blur and also gains one full stop of light. Light gain and loss characteristics are identical to those shutter settings possible in film. These shutter capabilities also enable low frame rate looks like (6, 12, 18, 20 FPS) Some thought this was only possible with Panasonic but it can be achieved with the F900 as well. The advanced functions of the electronic shutter also enables clear images to be made of computer monitors.
• 6. Many people ask what makes better slow motion... Panasonic’s 60p (100 Mb/second) or Sony’s 60i (180 Mb/Second).

Sony’s HD 60i scans an image at 60 times per second in fields, a slow motion effect can be created from 60i by treating the Sony HD field as a frame. The result is equivalent to shooting at 60 fps on film and doing a simple transfer to video. Because no two frames are the same, the result is very similar to film that was "over-cranked" to achieve slow-motion.

SLOW-MOTION PICTURE INFORMATION COMPARISON
Data bit rate per 60th of a second (approximate)

The Panasonic camera always records the image in 60p. To make 24p and other frame rates, this camera flags the frames to tell a complicated conversion box how fast to pay back the information. The Panasonic format also uses about one half of the digital bandwidth used by Sony. Both formats surpass NTSC’s ability to display the picture information.
• 7. The Sony Cine-Alta is designed for cinema. Over the last 100 years most films have been made using a film rate of 24 fps with a 180° shutter. That means that cinema camera’s usual exposure time of one frame is 1/48th of a second. The Cine-Alta uses an electronic shutter instead of a mechanical one. The electronic shutter can be used for creative purposes that would be impossible in a mechanical film camera. This ability to control motion blur and exposure time using this electronic shutter is great asset to digital cinematographers. It can even buy a full stop of light if the sun went down and you need one more shot.

ELECTRONIC SHUTTER SPEED = FILM SHUTTER ANGLE
When calculated using a 24 fps base (strikethrough means the angle is not possible in film cameras)

LENS FIELD OF VIEW COMPARISONS FOR 35MM FOCAL LENGTHS
35mm Academy 1.85:1 vs HDTV Full 1.85 (Calculations are approximate)

HD/FILM DEPTH OF FIELD

Anamorphic Hawk 70mm on 24p HDCAM Spherical 85mm Zeiss Super Speed

The doors to innovation are open. These images are part of my recent tests of anamorphic and 35mm lenses that help maintain vertical resolution in film out and also regain the depth-of-field of 35mm film.

For most of us film is our heritage, the photo-chemical process is part of our creativity. We have by no means given up on film but have embraced another and sometimes more liberating way to tell a story.

If you have any questions on how this information relates to your project, call us at (888) 247-3456
http://videoshoots.net/services/24p_image.htm

Shedding Some Light on High Definition

by Ken Freed, February 23, 2007
Freed is a News Correspondent for TV Technology Magazine.

Lighting technician Michael Anamal offsets lighting for a recent demonstration of the new ARRI D-20

Shooting video in HD requires fresh approaches to lighting, and those who sell lighting gear to the trade are in a great position to hear about the latest tips and techniques.
“In the conversations we’ve had with our customers,” said Duane Sherwood, director of communications for Lowel-Light in Brooklyn, NY, “we’ve found that the lighting adjustments fall into two areas, the amount of light you need and the way you light the scene.”

Sherwood said the change in the amount of light needed for HD stems from the change in camera technology.

“If you look at the evolution of video cameras over the past 10-15 years, each generation has done better with less light,” he said. “What we’ve found surprising is that the new HD cameras actually require more light.”

MORE OR LESS

The difference might be the higher resolution or the different circuitry in HD versus SD cameras, Sherwood said, “yet we’ve noticed that people shooting HD seem to add more lights now when before they’d been getting used to adding less and less, almost to the point that overhead ambient light was enough in some cases.”

Perhaps advanced lenses explain the shift, he said. In an effort to make HD video look like 35 or 70mm film, especially in made-for-TV movies, camera operators might add extenders to get a telephoto effect.

“When you add extenders, you need to add more light to compensate for what the extra lens elements are doing,” he said.

Regardless of the reason for needing more light, Sherwood said Lowel is seeing an increased demand for stronger fixtures with higher multiwattage lamps. “You need more flexibility with HD than with SD because the higher sensitivity of HD makes errors like stray light much more noticeable.”

Sherwood said HD is also improving the craft of lighting.

“I’m very excited about this,” he said. “Just like in woodworking or any creative endeavor where your individual sense of craftsmanship sets you apart from your competitors, so every good lighting director creates a unique style and look.”

With HD, he continued, “you now can use light more like in film by really paying attention to the details. You can create a sense of depth with so much more gradient of shade in the image that you almost get a 3D effect. It’s like the difference between an old computer Web browser with 256 colors and a new browser that can display millions of colors.”

The opportunity for greater craftsmanship is most apparent with those shooting TV programs and made-for-TV movies, Sherwood said, but those shooting local news also need to refine their craft in lighting for HD.

“You need to be sensitive to the subtleties of the image your camera will show,” he said.

NO FUNDAMENTAL DIFFERENCE

A slightly different view came from Gilles Galerne, president of K 5600 Lighting in North Hollywood, Calif.

“Aside from the obvious fact that the new format of 16:9 requires a larger or wider area to be lit, lighting for HD is not fundamentally different than lighting for SD, whether it’s a broadcaster’s shoot or a production shoot.”

Broadcasters usually are satisfied with the lighting they have on a subject, he noted, but when HD is used to replace 16 or 35mm film, then a more “contrasty” film-like look is required.

“From this we can deduce that any camera operator called for both styles of production needs to have equipment that adapts to each kind of shoot,” Galarne said.

Versatility and ease of set up for the lighting kit is paramount.

“In one day, you can shoot a stand-up interview where maximum raw output is needed to fight the sun; then you’ll be doing a beauty shot for the primetime magazine. The next day, you might be faced with shooting a drama or comedy piece where you must combine the roles of director of photography and chief lighting technician. Choices have to be made, and your equipment has to be ready to fulfill all duties.”

CHIN UP

The type of shoot determines the lighting choices, according to Gary Thomas, national sales manager for Videssence of El Monte, Calif.

“I’ve noticed our HD customers requesting softer light for their aging news anchors who want to hide as many imperfections as they can.”

At the same time, he said, “more and more news sets are installing light in the desk itself to illuminate under the chin. This has been done for years, but HD really shows up the need for dispelling that chin shadow, and this is most obvious with aging talent.”

A former lighting director at KDKA-TV in Pittsburgh, Thomas said that angles of light are much more critical in HD than SD, especially when working with multiple cameras.

“You need to match those shared details in the background and in shadow that show up from different camera angles,” he said.

As a consequence, “we’re getting a greater demand for portable lighting kits because field equipment is being used in the studio to get full spectrum lighting from all angles for multi-camera shoots. Nothing is worse than getting into the editing room and discovering that the same shot from different angles does not have the same lighting.”

A related issue is having full coverage of the wide-screen image area.

“HD news sets have to be lit to cover the entire desk with people spread out across the frame. Your lighting must extend to the outer boundaries of your wide shot’s image area, too, so you might want to use filters that diffuse light at the outer edges of the set.”

Thomas said the most useful high-intensity lamp in HD lighting is HMI (Hydrargyrum Medium Iodine or Hygerium Metallic Iodide), an arc light initially developed years ago for big searchlights.

“The new HMI lamps have lightweight ballasts, so they can be small enough to mount on a camera or carried around in a portable kit. HMI lights are always there for you. You can create whatever kind of scene or image you want to achieve with HMI.”

POWER UP

Improved batteries also are critical for HD lighting, said Jim Crawford, president of Frezzi Energy Systems, a division of Frezzolini Electronics in Hawthorne, NJ. “The new HD cameras and lights require tremendous energy efficiency, so we’re seeing a big demand for advanced lithium batteries that support maximum shooting time and stronger lighting, especially when shooting with a 200-watt HMI mounted on your camera.”

Crawford affirmed that multiple light angles are increasingly crucial.

“We have customers placing HMI lights all around a subject to get proper illumination, including back lights and key lights, which is relatively new with HD compared to SD.”

HD cameras tend to compress the contrast range, said Frieder Hochheim, president of Kino-Flo in Burbank, Calif.

“So unless you want your anchors highly defined, softer light seems to render faces better on HD than hard light. I can guarantee that from the viewpoint of the anchors, especially the aging anchors who freak out when they first see themselves on HD, they want softer light that eliminates some of the contrast.”

The trick to handling contrast in HD, Hochheim said, is to “maintain proper control over highlights and shadow detail. To get the skin tones right, I suggest you shoot some bracketed tests at different exposures with a highly textured surface like burlap on one side of the face and an 18 percent Kodak grey card on the other side of the face. If you don’t have time to shoot some tests to adjust your lighting, use a spot meter on highlights and shadows, and set your exposure somewhere in the middle.”

Hochheim also advised staying within the color parameters of your lighting.

“Know the color range of your camera and correct your balancing accordingly. If you’re mixing daylight and tungsten, for example, wrapping something blue around your subject will make color balancing easier. If you have high contrast in the background, unless you are shooting sports where you want every detail to show, focusing wide open on your subject and using a shallow depth of field may help. Of course, all these are very subjective calls. Your own tastes must determine your lighting.”

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