If a project has been acquired on film, it needs to be transferred to a digital image that can be manipulated within the DI Lab. Cineon has been utilised as the standard for many years, it is a 10 bit Log file invented by Kodak. It has proven its metal for FX work and now the DI workflow, although it has been slightly modified and ratified by SMPTE, the image is the same accept the header data holds more information, I shall look at this in more detail within the DI section.
Film scanners have existed for many years and are very accurate devices for transferring film images into data. They tend to be based on pin registration transports that scan a rock steady image. They have been proven within the VFX industry to be extremely reliable and to produce a great image. They can scan at high resolutions and are perfect for quality images; however they are relatively slow devices scanning accurately at a low frame rate, although in comparison they are cheap to telecines.
A film scanner scans original film stock: negative or positive print or reversal/IP. Units may scan gauges from 8mm to 70mm. (8mm, Super 8mm, 9.5mm, 16mm, Super 16mm, 35mm, super 35mm, 65mm and 70mm) with a very high resolution scanning of 2K or 4K film resolutions. (approx. 2K is 2048×1536 pixels and 4K is 4096×3072 pixels). The front end of a motion picture film scanner is similar to a telecine. The imaging system may be either a Charge Coupled Device (CCD) or Cathode Ray Tube (CRT) imaging pick up. A Xenon lamp, or as in the Arri, LEDs are used as the light source in a CCD imaging front end. In a CRT imaging system the CRT (also called a flying spot tube) is used as the light source and part of the scanning system. The CCDs or CRT convert the light to the video signals, which in turn are converted into data.
The Arri technology is deemed to be hardier because it does not decay as with a lamp. In essence, the image will in theory be exactly the same scanned six months apart with the same flashing unit.
Some makes of film scanner are intermittent pull-down which scan each frame individually, locked down in a pin registered film gate, taking roughly a second per frame, although with speed up in transfer speeds this has progressed making them an even more viable selection.
No single manufacturer builds a turnkey solution anymore; they offer parts to the package. When you frequent a provider of Digital Intermediate they will each have their own solutions selected from many different manufacturers: Lasergraphics - The Director, ARRI - Arriscanner, Filmlight - Northlight, IMAGICA technologies Corp, Cintel's diTTo.
Arriscan, a pin registered film transport & Spirit Datacine, real time continuous transport
Telecines (Virtual Telecines)
Telecines are sometimes termed as a continuous-scan film scanner, where the film frames are scanned as the film is continuously moved past the imaging pick up device. They evolved from earlier telecine mechanisms, and can act as such at lower resolutions for real time television transfers, which years ago before the advent of tape would be broadcast live. Modern telecines are capable of scanning at 2K and even 4K resolutions. They can transfer film to high definition (HD) and standard definition (SD) in real time, however for film transfer, they have to be slowed down to scan the frame to data correctly.
They sound like an all purpose machine, they are. In my humble opinion they are a jack of all trades and they have there followers. For the DI process I personally feel scanners have the edge in quality.
Firstly they do not use pin registration, so are not as stable as the original negative because the film is likely to move around during scanning. This could pose problems if later on you are trying to sort an effect. (Pin registered gates are available but dramatically slow the scanning process, like its counterpart) You would not consider 4K scanning from a telecine without pin registration as the accuracy at the higher speeds can be compromised.
Secondly sprocket and edge guides for film stability can cause distortions moving splices through the gate, especially on overlapping tape or bad splices. Handles are usually stipulated, so any movement or undulation will have disappeared by the time the first frame to be scanned is reached. Modern negative is usually fine because it is weld butt joins.
Thirdly the speed of transfer is significantly affected by the network connection, and also the transfer engine used. The transfer engine translates the raw data into the specified file format, usually Kodak Cineon log data. Transfer speeds vary because of these connections but it can range from 4 to 15 frames per second. The faster you try to scan can affect the images quality, the image sensors may not accurately measure the density which can increase the image noise.
The Spirit 2K and 4K supposedly have overcome the older generation’s foibles as 2K is now scanning in real time, however most dedicated DI facilities opt for a scanner because it is a dedicated machine for a dedicated job. Thus you are not shuffling schedules to suit client’s usage, in my opinion they are two different machines, either long tape to tape grading sessions or pure scanning. Both have important roles to play but each individually has been designed for their particular job – I feel telecines are a hybrid and not looked at as favourably by film purists.
Spirit DataCine 2k/4k - Digital Film Technology (2k realtime at 24fps or 4k Scans at 7.5fps - can be switched to Telecine mode, optional extra on 4k