Understanding Crop Factor on Super 35 Cine Cameras

When working with Super 35 cine cameras that have a crop factor greater than 1.6 compared to full-frame FF sensors, it is essential to understand and calculate the effective focal length of your lenses. This article aims to clarify the concept of crop factor, its implications, and the practical steps for calculation.

What is Crop Factor?

Crop Factor Definition: The crop factor is a ratio that compares the size of a camera's sensor to a full-frame 35mm sensor. A crop factor greater than 1 means the sensor is smaller than a full-frame sensor.

Super 35 Crop Factor Explained

The Super 35 format typically has a crop factor of around 1.5 to 1.6 compared to full-frame. However, if your specific Super 35 camera has a crop factor greater than 1.6, such as 1.7 or 1.8, you must account for this in your lens selection and framing.

Crop Factor and Effective Focal Length

To calculate the effective focal length of a lens on a Super 35 camera, you can use the following formula:

Effective Focal Length Actual Focal Length × Crop Factor

For example, if you have a 50mm lens on a Super 35 camera with a crop factor of 1.6, the effective focal length would be:

50mm × 1.6 80mm

Practical Implications of Crop Factor

Field of View (FOV)

Understanding the crop factor is crucial for achieving the desired field of view and depth of field, especially when transitioning from full-frame to Super 35 formats.

Lens Selection

It influences your lens choices. For instance, you may need to select lenses with different focal lengths to achieve the same framing you would get on a full-frame camera.

Historical Context and Comparison

It's important to note that using a medium format camera involves a bigger sensor than the standard full-frame sensor. This can lead to different perceptions of the field of view (FOV) when comparing still photography to cinematography.

For those used to stills, the 50mm lens FOV is roughly thought of as equal to the FOV of the human eye because of the wide image area exposed on the film. In the movie world, film was fed through the gate vertically, creating a smaller image area to expose on. This means that a 35mm lens had the FOV of the human eye.

When shooting on a crop framed DSLR like the Canon 70D with a crop factor of 1.6:

35mm lens × 1.6 56mm (roughly 50mm)

When shooting on Super 35mm, as mentioned by Dimitrios, the crop factor is 1.4:

35mm lens × 1.4 49mm (roughly 50mm)

Whether the difference is significant to worry about depends on your usage. For telephotos, the difference might matter, but for most other applications, the crop factor is only important if you are deeply familiar with the lens FOV from the still world.

In the end, these crop factors come into play when you are used to the 35mm stills world and shoot on a full frame camera like the Canon 5D.

For more detailed insights and historical explanations, watch our Pull My Focus video below.

Conclusion

Keeping track of the crop factor is essential for effective shooting with Super 35 cine cameras, especially when it exceeds the typical 1.6 value. Accurate calculation and understanding of crop factor will help you achieve the desired visual effects and deepen your understanding of cinematography.