updated 28 January 2003
Simulating a 35mm Motion Picture Clarity Signature
an article by Daniel Broadway
Hello, and welcome to my “CineAlta” tutorial. I call it that because while most would consider this a film-look tutorial, I am actually going for the HD 24p look. To be truthful, I am one of the new technology buffs. While I will admit film does have wonderful color and a great dynamic range; it is also plagued by film grain, color smearing, and dust and scratches. Therefore, I prefer the Star Wars Episode II look which was shot on 24p HD Sony HDW-F900 (CineAlta) cameras with Panavision lenses. So that is the “look” I am going for in this tutorial. If you are lucky enough to own a Panasonic AG-DVX100, then you need not read the “motion signature” part of this tutorial, as you already have a 24p mode on your camera and the proper shutter speed settings. Let’s begin by going over some of the key things that make HD Cinema cameras (and motion picture film) look the way they do.
Video Motion Clarity Signatures
The biggest difference to me between 24p and 60i video is the motion signature created by a camera’s recording mechanism. NTSC video records 30 images per second, however, each image is divided into two separate fields that interlace to form a complete image. This results in 30 odd-field images and 30 even-field images recorded each second. Consequently, 60 separate half-resolution images are recorded every second. Movement and its associated motion blur are therefore captured at a much quicker 1/60th of a second, with a negligible blanking interval in between field exposures. The outcome produces significantly less motion blur, and a sharper image, as the images are captured more frequently and for a shorter duration. This is what gives video its too-smooth look. It looks real like the human eye sees, and therefore not suitable for the fantasy worlds of motion pictures.
HD Cinema (and motion picture film) is recorded at 24 images per second (24fps) as full frames. Motion blur is the blurred effect you get when exposing an image with movement. With a typical 180 degree shutter, the exposed image movement, and subsequent motion blur, is therefore recorded for 1/48th of a second and results in more motion blur than 1/60th like NTSC. This gives you the motion clairity signatures of HD Cinema and 35mm motion picture film.
Color and Dynamic Range (Gamma)
HD Cinema cameras are loaded with 2/3 inch CCDs engineered to perfection to create breath-taking detail, sharpness, a wide-dynamic range (levels from black to white, and everything in between), and brilliant color. Of course it’s not yet up to the pixel count of film (12 million pixels); word has it that George Lucas has contracted with Sony to build a new generation of ultra high-definiton cameras that record 10 megapixels of information. When these cameras become standard, motion picture film cameras will be dead.
Professional Cinematography
While this tutorial is interested only in color corrections and motion clairity, I feel it neccessary to point out professional camera movement. To get the “film look,” use zooms sparingly, and if you must use a zoom, do so slowly… almost to the point that it’s not noticeable. Also, when using close ups, try to shoot with a shallow depth of field by keeping the iris open as much as possible. This will also give you a shallow depth of field. Move slowly, and gently. Use handheld shots sparingly, unless it’s the effect you are after. Use a stablizer device, such as a steadicam for moving shots, and a tripod for stationary shots.
Simulating a 35mm Motion Picture Clarity Signature
I have experimented with various techniques for simulating motion picture motion clarity, and I believe this is the simpliest and most effective way of doing it. Shoot your footage as 60i (normal video) and capture it into your computer. I will do this process in Adobe After Effects; however, I am aware that Apple’s Final Cut Pro and probably Adobe Premiere are also capable of doing this.
- Import your clip into Adobe After Effects projects.
- Right-click the video clip and select Interpret Footage > Main.
- Once you get into this menu, you will see a “Seperate Fields” option in the middle of the menu. Select it, and then select “Lower Field First” and check “Motion Detect” (best quality only).
- Import another of the exact same clip.
- Repeat the above process, but choose “Upper Field First.”
- Drag your first clip (lower field) into the composition, and set its quality to “best.”
- Now drag the second clip (upper field) into the composition on top of the first clip.
- Set the upper field clip’s opacity to 50%. This gives us a close approximation to the motion blur that would be captured at 1/40th of a second, and therefore closer to the motion clarity of motion picture footage.
Left: 1/60th Shutter Speed Right: 1/48th Shutter Speed (faked)
Note the motion blur difference on the hand and arm.
- Create a new composition.
- Drag your first composition into your new second one. Set its mode to “Best.”
- Now go to Effect > Time > Posterize Time. The default should be set to 24 frames per second. This effect locks a layer to a specific frame rate. It will play back and look like 24 frames per second, even though you can export this composition as 29.97 fps.
- Render out this composition and watch the end result.
You should now have a pretty close approximation to the film-look motion clarity signature, as so many people like to call it. Hope this has been helpful, and now we’ll move on to color timing.
This article originally appears at
http://www.geocities.com/pixelmagic2002/CineAlta1.html.
Written by Daniel Broadway.
Thrown together by Chris Hurd.
Please direct questions to the DV Info Net Community Forums.
