Ever come across this alien-like icon while cleaning or setting up your camera and don’t know what it is? Read more, where we discuss what this symbol is and its practical applications.
What is that?
This symbol resembles the Greek word Phi (a circle with a line through it) and is usually located at the top of the camera body. It is called focal plane mark or film plane mark. It is mainly used to indicate the position of the sensor/film inside the camera body. The position of the sensor/film is then used to determine the camera’s focal plane, where light rays from the subject passing through your lens converge into a sharp image.
The practical application of this symbol in photography
1. The practical application of this symbol in photography
The minimum focusing distance is not measured from the tip of the lens but measured from this point onwards. This information lets you know how close your lens can be to your subject and still be in focus. Therefore, it is very useful for macro and product photographers to make their necessary calculations to plan the shoot so that they do not touch the subject when shooting.
2. Determining the Focus-to-Subject Distance
The focal plane mark also serves as a reference point when measuring the focusing distance. Although the sensor is located inside the camera body, this icon allows us to pinpoint the exact position of the focal plane inside the camera. Focal area is the surface on which the image is recorded. It is important to note that the focal plane will always remain in a fixed position regardless of the lens used. And by knowing the exact focus distance of the subject to the sensor, photographers will be able to calculate the depth of field and use the optimal aperture value during shooting with reference to the focus scale.
3. Measure the distance to the object
The focal plane icon also serves as a consistent point for measuring the distance of the subject to the camera. This distance information is often used as an anchor point for easy post-processing when you merge images or create composite images, as it ensures consistent focus and image proportions. This distance information will often also be used in a set record to mark the subject’s position during e-commerce product shooting to easily produce reproducible results.
4. Lens correction
In addition to all the practical applications in photography, this focal plane mark is also technically used to calibrate photographic camera lenses. It helps technicians pinpoint the exact position of the focal plane to calibrate lenses for optimum quality and sharpness during lens focusing.
Conclusion
It should be noted that different camera models or lens systems may mark the focal plane symbol differently and in different positions. Therefore, you should always consult your camera or lens manual for specific information on how to mark the focal plane in a particular system. This icon when put to use can take your image quality to the next level.
