C-FORMAT - Ampex / Sony (IEC 558)
This non-segmented format reflects the third iteration of the SMPTE 25.4 mm helical video recorder standard. Appearing in 1978 this format was designed to provide 'stunt' capabilities such as still-frame, picture-in-shuttle and slow motion that were impossible with 'quad' recorders. C-format was the vehicle for the introduction of AST (auto scan tracking) and the PAL variant was promptly embraced by the EBU.
| Signal system |
| Analogue, composite, non-segmented. |
| Scanner |
| Geometry |
Helical |
| No. of rotating heads |
3 or 6 * |
|
| Scanner diameter (top) |
134.62 |
mm |
| Rotation speed |
50 |
rev/s |
| Tracks/revolution |
1 |
|
| Head-to-tape speed |
21.39 |
m/s |
| Video track angle |
2.56 |
degree |
| Track width |
160 |
µm |
| Track pitch |
214 |
µm |
| Azimuth |
Perpendicular |
|
| Tape Properties |
| Coercivity |
650 |
Oe |
| Type |
Cobalt-modified oxide |
| Width |
25.4 |
mm |
| Thickness (total) |
28 |
µm |
| Tape Consumption |
| Linear |
239.8 |
mm/s |
| Areal |
0.37 |
m2/min |
| Shelf volume |
952 |
cm3/h |
| Electrical Characteristics |
| Sync tip carrier frequ. |
7.16 |
MHz |
| Blanking |
7.68 |
MHz |
| Peak white |
8.90 |
MHz |
| Shortest wavelength |
2.4 |
µm |
* Normal configuration with 3 heads has vertical interval 'dropout' and
space for four longitudinal audio tracks. 6 heads option provides continuous recording
with space for 3 audio tracks. One variant uses the 'sync' track space for digital audio.
IEC 558
|
|
