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F--

Nikon Camera

Severity: Minor

Source: OnlyErrorCodes.com — Every error code. One place.

Nikon F-- No Lens Mounted — Fix Guide

What Does This Error Mean?

F-- on a Nikon DSLR means the camera sees no CPU lens attached — either no lens, an older non-CPU lens, or a CPU lens with bad contacts.
If you have a CPU lens (any AF lens or recent manual lens), check the gold contacts and reseat the lens firmly.
If you're using an older non-CPU lens (AI-S manual lens), F-- is normal — set non-CPU lens data in the menu.

Affected Models

  • Nikon D850
  • Nikon D750
  • Nikon D7500
  • Nikon D5600
  • Nikon D3500
  • Nikon D6

Common Causes

  • Lens not fully mounted (CPU lens not aligned)
  • CPU contacts dirty on lens or body
  • Older non-CPU lens (AI/AI-S/E series) attached normally
  • Lens mount damaged on body or lens
  • CPU contacts physically damaged

How to Fix It

  1. Confirm the lens is fully mounted.

    Press the lens release button on the camera and rotate the lens off.
    Reattach by aligning the white dot on the lens with the white dot on the camera body.
    Rotate until you hear the click.
    F-- often clears just from this clean remount.

  2. Clean the contacts.

    On the back of the lens, look for the row of gold contacts.
    Wipe with a clean dry microfiber cloth.
    Same for the matching contacts inside the camera lens mount.
    Dust or oil on contacts is the most common F-- cause.

  3. Check if your lens has CPU contacts.

    If the back of your lens has 5 or more gold contacts in a row, it's a CPU lens — F-- shouldn't appear.
    If the lens has no contacts (just the metal mount), it's a non-CPU lens (AI/AI-S series).
    F-- is normal in that case — see step 5 for non-CPU lens setup.

  4. For CPU lenses with persistent F--.

    If F-- persists with a CPU lens after cleaning contacts, the lens or body has damaged contacts.
    Try a different lens to isolate.
    If F-- only with one lens: lens needs repair or replacement.
    If F-- with all lenses: body mount needs Nikon service (200–400 USD).

  5. For non-CPU lenses, set lens data.

    If using an AI/AI-S lens, F-- is expected.
    Menu → Setup → Non-CPU Lens Data → enter focal length and max aperture for your lens.
    Pro/enthusiast bodies (D7500, D850) support metering with this data.
    Entry-level bodies don't allow non-CPU lenses to meter.

Frequently Asked Questions

Will the camera shoot with F-- displayed?

Depends on the body.
Pro/enthusiast bodies (D850, D7500, D6): yes, with manual exposure or non-CPU lens data set.
Entry-level (D3500, D5600): may refuse to shoot without a CPU lens.
Newer entry-level bodies often won't operate at all without a CPU lens — that's by design.

Can I use AI-S lenses on a D3500?

Mechanically yes (the mount is compatible), but the body won't meter or autofocus.
You'll be in fully manual mode with no light meter readings.
Some users do this for portrait or studio work where they have time to dial in exposure.
For everyday shooting, use CPU lenses.