The question of which ISO is "cleanest" depends heavily on the context. There are two main interpretations:
1. Cleanest in terms of Cleanroom Classification (ISO 14644):
In the context of cleanroom environments, ISO 1 represents the cleanest class, while ISO 9 is the dirtiest. Even ISO 9, however, is significantly cleaner than a standard room. The most frequently used classes are ISO 7 and ISO 8. [Source: Reference 1, Reference 3]
- ISO 1: The highest level of cleanliness, with the fewest airborne particles.
- ISO 9: Still a controlled environment, much cleaner than a typical room.
- ISO 7 & ISO 8: Commonly used cleanroom classifications.
2. Cleanest in terms of Image Sensor Noise (Photography):
In photography, a lower ISO setting generally produces a "cleaner" image with less noise (grain). While there's no single "cleanest" ISO, the lowest native ISO setting of a camera is often considered optimal for image quality, minimizing noise. Different cameras have different native ISOs; some cameras may have a native ISO of 100, others 400, for example. Using ISOs beyond the native ISOs usually introduces digital noise. [Source: Reference 4, Reference 5, Reference 6, Reference 7, Reference 8, Reference 9, Reference 10]
- Lower ISOs (e.g., 100, 200): Generally produce cleaner images with less noise. However, the exact best ISO depends on the specific camera model.
- Higher ISOs: Introduce more noise. While sometimes necessary in low-light conditions, they compromise image quality.
It's crucial to understand the context when referring to "cleanest ISO." The term has distinct meanings in cleanroom technology and photography.
