Certified Professional Photographer (CPP) Practice Exam

A filter factor of 8x is equivalent to how many stops of increase?

1. 2

2. 3

3. 4

4. 1

The correct answer is: 3

To determine how many stops of exposure increase a filter factor of 8x represents, it's essential to understand how exposure stops work in photography. Each stop of exposure effectively doubles or halves the amount of light that reaches the camera sensor. When applying a filter, the filter factor indicates how much light is reduced. A filter factor of 8x means that the amount of light hitting the sensor is decreased to one-eighth of what it would be without the filter. To find out how many stops this reduction corresponds to, we can look at the doubling concept of stops: 1. The first stop halves the light (1/2), 2. The second stop halves it again (1/4), 3. The third stop halves it once more (1/8). So, halving the light three times leads to an overall decrease of light to one-eighth, which means a filter factor of 8x corresponds to an increase of 3 stops of exposure. Therefore, using this filter requires an additional 3 stops of light to achieve the same exposure level as without the filter. This understanding is crucial for adjusting camera settings, ensuring the right amount of light reaches the sensor for proper image exposure.