Mengenal Reciprocal Rule

Get to Know the Reciprocal Rule

Usually when you hold the camera it cannot be completely still and stable. Your body can sway and you may not be aware of it, causing the photos you take to be blurry. Now with the reciprocal rule, you can overcome this by ensuring that the camera's shutter speed is at least the inverse of the lens focal length. For example, if you shoot with a full frame camera at a focal length of 80mm, the shutter speed must be set to a minimum of 1/80 second. If you use a zoom lens and use a focal length of 400mm, then your shutter speed will be at least 1/400 second.

Using a fast shutter speed can reduce camera shake because the longer the focal length, the greater the potential for camera shake.


The red line indicates potential camera shake. We can see that the greater the focal length, the wider the red line, which means the potential for camera shake is greater.

Please remember that if you use a camera with a smaller sensor, for example an APSC camera, you have to calculate the effective focal length, known as the equivalent field of view, by multiplying the focal length x crop factor. For example, if you use an 80-400mm lens on a camera with a crop factor of 1.5x, if you use a focal length of 400mm then the minimum shutter speed must be 1/600 second. (400 x 1.5 = 600).

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