The following phenomena may occur when shooting under fluorescent lighting, LED lighting, sodium lamps, mercury lamps, etc.
- The screen flickers when displaying the live view screen or during movie shooting.
- Banding appears or colors change in the shot still image.
This is a phenomenon called flicker, and it is not a malfunction.
Examples of flicker
Change in color
Banding in an image
Why flickering causes issues
Characteristics of lighting
Although most fluorescent lights are now equipped with inverters, older fluorescent lights flicker 100 or 120 times per second.
In contrast, increasingly common LED lighting and signage flicker more rapidly, at several hundred or thousands of times per second.
Changes in brightness from this flickering may cause issues in images.
- Flickering cycle: 100 or 120 Hz
- Characteristics: Often, the color of objects changes with continuous fluctuations in brightness as these flickering lights change from bright to dark.
- Flickering cycle: on the level of hundreds or thousands of Hz
- Characteristics: This lighting repeatedly and rapidly turns on and off.
Structure of a camera shutter
In an interchangeable lens camera, a focal-plane shutter is positioned in front of the image sensor. The focal-plane shutter consists of front and rear curtains. By adjusting the difference between when each curtain begins to move, cameras control the exposure time (shutter speed).
For example, when the shutter speed is set to 1/1000 sec., the rear curtain follows the movement of the front curtain and forms a slit-shaped opening to expose the image sensor.
Also, it takes 1/1000 sec. for the rear curtain to pass a point on the screen after the front curtain has passed the same point.
On the other hand, it takes from about 4 milliseconds to several dozen milliseconds after the front curtain begins moving until the rear curtain stops moving. This amount of time varies depending on the shutter type used.
Examples of changes before and during shutter movement:
Before shutter movement
During shutter movement
- A: Front curtain
- B: Rear curtain
- C: Exposure time (shutter speed)
Watch the video illustrating shutter movement and exposure time:
An image in which the brightness and colors vary between the top and bottom because of the varying exposure timings at the top and bottom of the image sensor
An image in which changes in brightness appear as banding due to shooting under LED lighting with a rapid flickering cycle or shutter slit movement requiring a longer time
For details on shooting images with reduced effect of flicker, refer to the page below.
How to reduce flickering, which is partial or total discoloration of an image or horizontal banding