Source Four Focal Length, Pattern Size and Image Diameters
Question
What Size Patterns Do Source Fours Use and What Are The Image Diameters and Focal Lengths?
Answer
Source Four uses "A" and/or "B" size patterns and Source Four jr uses "M" size patterns.
| Type | Outer Diameter | Max Image Diameter |
| A | 3.93"/100mm | 2.95"/75.0mm |
| B | 3.38"/86mm | 2.53"/64.5mm |
| M | 2.57"/65.5mm | 1.94"/49.5mm |
The gate size in a Source Four is 3.12"/79.24mm.
The gate size in a Source Four jr is 2.15"/54.61mm.
Focal Length Source Four:
90 degree | 2.13"/54.1mm |
70 degree | 2.67"/67.82mm |
50 degree | 3.3"/83.82mm |
36 degree | 4.8"/121.92mm |
26 degree | 6.8"/172.72mm |
19 degree | 9.3"/236.22mm |
14 degree | 11.05"/280.67mm |
10 degree | 17.8"/452.12mm |
5 degree | 25.5"/647.70mm |
Focal Length Source Four jr:
| 26 degree | 4.66"/118.3mm |
| 36 degree | 3.27"/83.18mm |
| 50 degree | 2.33"/59.18mm |
| Fixture | Actual Field Angle (per 7/2003 testing) | Lens Focal Length |
| S4 15-30 | 16.2° minimum | 278mm |
| 31.3° max | 141mm |
| S4 25-50 | 26.9° minimum | 166mm |
| 49.0° max | 87mm |