Sensor and Shutter: The Two Main Parts of Your Camera

In my practice, it often happens: the buyer meticulously double-checked the shutter, saw an excellent figure of 20,000 frames, and will give it back money, I came home... And when taking evening portraits, the pictures show a bright red or blue dot on the very in a prominent place!

These are **hot or dead pixels (Dead/Hot pixels)** of the sensor. With age and high mileage of the matrix, their number inevitably grows.

How to correctly take 2 test frames in 1 minute

Test 1: Search for dead (white/colored) pixels on dark

1. Place the lens cap on the lens (or close the mount with a plug).
2. Set the camera to manual mode `M`, set ISO 800 and shutter speed **1/2 second**.
3. Take 1 frame in RAW (.NEF). Open it on your smartphone or PC screen with 100% zoom. If you constantly see burning light dots on a black background are hot pixels.

Test 2: Search for dark (“stuck”) pixels on light ones

Shoot a white wall or sheet of paper at f/8 and ISO 100. If there are black dots, check if there is dust on the sensor filter or burnt out sensor.

Does Nikon have internal pixel remapping?

Yes! Modern Nikon cameras (especially Z and later D850/D780 mirrorless cameras) have a **Pixel Mapping function in the menu (Pixel remapping)**. The processor masks the dead point by interpolating neighboring working pixels. In old On D700/D90 DSLRs, remapping was done only in our service through service software.

Sensor Defect Rating Table

Defect type	What it looks like in the photo	Treatment in the service
Dead pixel	Always white or black point at any ISO	Remapping (software hiding)
Hot pixel (Hot)	Red/blue dot at high ISO and slow shutter speeds	Normal for a hot matrix (can be eliminated by noise reduction)
Dust spot	Blurry gray circle at f/16 – f/22	Regular wet cleaning of the matrix in the service