Diving Under the Hood of Nikon Metadata

When you open regular file properties on your computer, Windows displays standard information: excerpt, aperture, ISO and lens model. But the most important thing - **development of the bolt group** - is not there.

Why? Because Nikon's engineering team hid the meters in a binary **MakerNote** block. Let's look at how this system works from the inside.

Tag 1: `ShutterCount` (Or `ImageCount`)

In SLR cameras (D90, D300s, D700, D750, D850) this tag counts **each physical release of the shutter curtain**.

• We pressed the trigger - the electromagnet cocked, the curtains moved, the counter in the EEPROM increased by +1.
• If you took a photo in flash or bracketing mode, one is added for each shot.

Tag 2: `MechanicalShutterCount` (Appeared in Z series mirrorless cameras)

With the release of mirrorless cameras Nikon Z6, Z7, Z50, the system has become more complicated. Mirrorless cameras have **electronic shutter (Silent Shutter)**, which does not wear out mechanical curtains.

The engineers introduced two separate fields:

1. MechanicalShutterCount- shows only the physical actuation of the metal bolt block.
2. TotalShutterCount(or total `ShutterCount`) - total shots fired, including millions of silent ones frames.

Why do you need to know the difference?

Imagine: a seller on Avito gives away a Nikon Z6 II with a mileage of 150,000 frames. It would seem that the shutter is running out. But we we run the file through our service and see:

• Total Shutter Count: 150,000
• Mechanical Shutter Count: 12,400

Conclusion: the photographer shot time-lapses with a silent shutter! The mechanics of the carcass are almost new. You can safely take the camera with a good discount.

Gate Key Tag Differences Chart

Tag name	What exactly does it take into account?	Which cameras have
ShutterCount/ImageCount	Physical shooting of curtains (in mirrors)	All Nikon DSLRs (D40 – D850)
MechanicalShutterCount	Only metal shutter movements	Z-series mirrorless cameras (Z5, Z6, Z7, Z8)