Red Dots in the Lens Flare or “Sensor Flare”
If you have seen red dots when shooting directly towards the sun or a very bright light, what you are seeing is to be expected. This is an optical artifact caused by the OLPF (Optical Low Pass Filter) in the camera between your lens and sensor. The OLPF acts like two mirrors facing each other and as the light shines through the lens and reflects off the OLPF, the red dots become more visible as you reduce the aperture on your lens.
Note that this is not just a RED camera issue but happens any other digital cameras that have a Low-Pass Filter or other structure in front of the sensor.
The red dot flare issue will only occur when specific conditions are met:
- The camera is pointed at a very bright light or directly at the sun.
- The lens is stopped down to a very small aperture, around f/8 – f/11 and smaller.
There are ways to reduce this red dot / sensor flare’s appearance while shooting:
- Use ND (Neutral Density) filters in front of your lens. This will allow you to open up the aperture to compensate for exposure, reducing or eliminating the sensor flare grid pattern.
- If you are using the Standard or Low Light Optimized OLPF in your camera, switching to the Skin Tone-Highlight OLPF will reduce or eliminate the sensor flare grid pattern.
- As a last resort, you can modify your shot’s angle or framing. In some cases, it may be easiest to avoid shooting directly into a bright light altogether. Changing your angle or moving the light source is a good way to avoid this issue.