Understand how your camera’s sensor size affects the effective focal length and aperture of your lenses when shooting BRAW.
Calculation Results
Crop Factor: 1.0x
Effective Focal Length (35mm equivalent): 0 mm
Effective Aperture (DoF equivalent): f/0
What is the BRAW Crop Factor & Lens Calculator?
The BRAW Crop Factor & Lens Calculator is a tool designed for cinematographers, photographers, and videographers working with Blackmagic Design cameras and other systems that utilize sensors smaller than full-frame 35mm. This calculator helps you understand and determine the effective focal length and effective aperture (f-stop) of your lenses when mounted on a camera with a specific sensor size. This is crucial for accurately predicting your field of view and depth of field, ensuring you achieve your desired cinematic look.
Why is Understanding Crop Factor and Effective Focal Length Important?
Sensor size directly impacts how a lens behaves. A lens designed for a full-frame camera will have a different field of view and depth of field when used on a camera with a smaller sensor. Understanding these changes is vital for:
- Accurate Framing: Knowing the effective focal length helps you choose the right lens to achieve the desired shot composition and field of view.
- Consistent Look: Maintain a consistent visual style when switching between cameras with different sensor sizes (e.g., a full-frame mirrorless and a Blackmagic Pocket Cinema Camera).
- Depth of Field Control: The effective aperture influences your depth of field, which is critical for creative control over focus and background blur.
- Lens Investment: Make informed decisions when purchasing lenses, understanding how they will perform on your specific camera system.
This calculator demystifies the relationship between sensor size, focal length, and aperture, empowering you to make precise creative and technical choices.
How to Use the BRAW Crop Factor & Lens Calculator
- Select Camera Sensor Size: Choose your camera's sensor size or a common equivalent (e.g., Micro Four Thirds, APS-C, Blackmagic Pocket 4K).
- Enter Lens Focal Length (mm): Input the native focal length of your lens (e.g., 50mm, 85mm).
- Enter Lens Aperture (f-stop): Input the native maximum aperture of your lens (e.g., f/2.8, f/1.4).
- Click Calculate: The tool will display the crop factor, the effective focal length (35mm equivalent), and the effective aperture (for depth of field comparison).
The calculations provide a 35mm full-frame equivalent, which is a common reference point in filmmaking and photography. This helps you visualize how your lens will behave compared to a full-frame system.
Frequently Asked Questions
Crop factor is a multiplier that describes how much smaller a camera's sensor is compared to a standard 35mm full-frame sensor. A crop factor of 2x means the sensor is half the size of a full-frame sensor in both width and height, effectively cropping the image and making lenses appear "longer."
When you use a lens on a camera with a crop sensor, the field of view becomes narrower, as if you were using a longer focal length lens on a full-frame camera. To find the "effective focal length" (35mm equivalent), you multiply the lens's native focal length by the crop factor.
While the actual light-gathering capability (T-stop) of a lens doesn't change, the *effective depth of field* changes. A smaller sensor at the same f-stop will produce a greater depth of field than a full-frame sensor. To get the equivalent depth of field as a full-frame, you multiply the lens's f-stop by the crop factor to find the "effective aperture."
A Speed Booster (or focal reducer) is an optical adapter that effectively reduces the crop factor of a smaller sensor, allowing it to capture a wider field of view and gather more light from a full-frame lens. It makes a lens appear wider and brighter than it would natively on the crop sensor.
Blackmagic Design cameras come with various sensor sizes (e.g., Micro Four Thirds in the Pocket 4K, Super 35 in the Pocket 6K, full-frame in the URSA Mini Pro 12K when shooting 8K/6K). Each sensor size has a different crop factor relative to a full-frame 35mm sensor, influencing how lenses behave on that specific camera.
No, the BRAW codec itself does not affect the crop factor. The crop factor is determined by the physical size of the camera's sensor and the resolution/sensor area you choose to record from (e.g., shooting 4K on a 6K sensor might involve a crop). The codec only dictates how the data from that sensor area is compressed and stored.
Anamorphic lenses introduce their own squeeze factor, which is a separate consideration from crop factor. When using anamorphic lenses on a crop sensor, you would first calculate the effective focal length and aperture based on the crop factor, and then apply the anamorphic de-squeeze factor in post-production to achieve the final aspect ratio.
Not necessarily. While larger sensors generally offer better low-light performance and shallower depth of field, smaller sensors can provide greater depth of field (useful for documentaries or run-and-gun), allow for smaller and lighter lenses, and can be more cost-effective. The "best" sensor size depends on your creative and practical needs.
Yes, the principles of crop factor, effective focal length, and effective aperture apply equally to still photography. This calculator can be used by photographers to understand how their lenses will perform on different camera bodies, regardless of whether they are shooting stills or video.
The 35mm full-frame sensor (approximately 36x24mm) has historically been the standard reference point for focal lengths due to its prevalence in film photography. When discussing effective focal length, it's common to refer to what a lens would look like on a 35mm full-frame camera to provide a universal understanding of its field of view.