What to Do If Your Camera’s Autofocus (AF) Starts Failing

Your camera was working perfectly, focusing fine yesterday, and suddenly the AF becomes unpredictable: it hunts, won’t lock, or lags behind the subject. Before thinking about a repair (€200–500), run through this diagnosis. 70% of cases are resolved without opening the camera.

Step 1: Is It the Camera or the Lens?

This is the first thing to rule out. Swap lenses.

• If you put on another lens and it focuses fine → the problem is the lens. Jump to step 7.
• If all your lenses fail on this camera → it’s the camera. Continue.
• If only one lens focuses poorly and the rest are fine → that lens is the problem.

Time: 2 minutes.

Step 2: Dirty Electrical Contacts

A VERY common cause, especially on cameras over 2 years old or those that have been in humid environments.

Typical symptom: Intermittent AF. Sometimes it focuses, sometimes it doesn’t. Swap lenses and it comes back.

How to fix it:

1. Turn off the camera.
2. Remove the lens.
3. Clean the gold contacts on the camera’s mount with a cotton swab dipped in 99% isopropyl alcohol (DO NOT use ethyl alcohol—it leaves residue).
4. Do the same with the lens contacts.
5. Let it evaporate for 30 seconds.
6. Mount and test.

If AF works again, you’re done. Cost: €0. Time: 5 minutes.

Step 3: Incorrect Camera Settings

More common than you think. Check:

• AF mode: Is it in AF-S (single) when it should be in AF-C (continuous) for a moving subject? Is it accidentally in MF?
• AF area: Is it set to “point AF” aimed at an empty area of the frame? Temporarily switch to “Auto AF” and test.
• Subject detection: If your camera has eye/face/animal detection, disable it temporarily to rule out firmware bugs.
• Custom AF-ON: Did you reassign buttons and break the workflow? Reset to default.
• Joystick/touch AF sensitivity: Overly sensitive settings can confuse the system.

Quick reset: Many cameras have “Reset camera settings” in the menu. You lose your presets but rule out the problem. Time: 3 minutes.

Step 4: Outdated Firmware

This rarely happens on new cameras (the latest official firmware usually includes AF fixes). It’s more common on cameras bought second-hand from 2–3 years ago—they come with old firmware.

1. Go to the manufacturer’s website:
   • Canon: canon.es → Support → Your model → Firmware
   • Sony: sony.es → Support → Model → Updates
   • Fujifilm: fujifilm.com/global/support → Firmware
   • Nikon: nikon.es → Support → Drivers
2. Compare with your current version (Menu → Setup → Firmware version).
3. If your firmware is 2+ versions old, update with the camera fully charged and using the original battery (NOT a compatible one—some updates break with non-official batteries).

After updating: AF improves in 30% of cases where the problem was firmware. Time: 30 minutes including download.

Step 5: Bad Battery

Yes, it sounds odd, but it happens. When the battery has less than 60% health, the camera reduces power priority to the AF motor to save battery. AF slows down noticeably and sometimes fails.

Test: Try a new original battery. If AF comes back, the battery was the problem.

Read here about batteries and battery health →

Step 6: Dirty Sensor or Mirror (DSLR)

Only applies to DSLRs. Mirrorless cameras don’t have a separate AF module from the sensor.

Symptom: AF fails only in certain areas of the frame (typically the center).

Diagnosis:

1. Take a photo of a white wall at f/22, focus to infinity, with the camera aimed at a white wall.
2. View the photo at 100%.
3. If you see dark spots → dust on the sensor (can affect AF if it’s over the phase-detection module).

Solution: Professional sensor cleaning (€50–90 at a specialized workshop). DO NOT attempt to clean the sensor yourself without experience—expensive damage if done wrong.

For mirrorless cameras, the equivalent problem is dust on the sensor affecting AF detection quality. Same solution.

Step 7: The Lens Is the Problem

If step 1 indicated it’s the lens, several possible causes:

a) Dirty Lens Contacts

Same solution as step 2 but only on the lens. 5 minutes.

b) Stuck Manual Focus Ring

If the lens has an MF (Manual Focus) ring, try moving it. If it’s stiff or stuck, the AF may be fighting against it. Internal cleaning (service): €80–150.

c) AF Motor (USM, STM, HSM, etc.) in Bad Condition

Symptom: Strange noise during focusing (squeaks, vibrations). Repair: €150–400 depending on the lens. On mid-range lenses (50mm f/1.8, 24-70mm f/4), it’s usually cheaper to replace the lens than repair the motor.

d) Off-Axis Calibration

The camera consistently focuses in front of or behind the subject. This is a desynchronized AF micro-adjustment. Most DSLRs have “AF Fine Tune” in the advanced menu. On mirrorless cameras, it’s rare, but some models support it.

Step 8: Official Service Center

If you’ve reached here, you’ve ruled out the cheap fixes. It’s time for official service:

• Canon: canon.es/support → Repair. €60–90 diagnosis + variable repair cost.
• Sony: sony.es → Support → Repair. Similar.
• Fujifilm: fujifilm.com/global → authorized centers in Spain.
• Nikon: nikon.es/support → official centers.

Typical AF module repair cost:

• Mid-range DSLR: €150–280.
• High-end DSLR: €280–500.
• Full-frame mirrorless: €300–500.
• APS-C mirrorless: €200–350.

It’s not worth repairing if the repair cost is > 40% of the camera’s current used market value. In that case, sell the body “for parts” (typically you get 20–30% of the normal price) and buy another unit.

If You Bought the Camera at Camera Market

If it’s within the 12-month warranty, don’t diagnose yourself: call us directly and we’ll handle shipping and repair at no cost. How the warranty works →

Steps 1–3 (lens, contacts, settings) you can do beforehand to rule out the trivial. If you confirm it’s a camera issue, call:

• Email/WhatsApp in the footer of cameramarket.es
• A courier picks up the camera from your home the next day
• Repair covered + loan of an equivalent body if it takes more than 7 days

When It’s Urgent

Intermittent AF that only appears sometimes is NOT urgent—diagnose calmly.

AF that NEVER works from one day to the next IS urgent—it’s usually a serious electronic failure that progresses. Send it to the workshop before something else more expensive fails.

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Read also: how the 12-month warranty works → And how many shutter actuations are too many →