How can I tell if my Canon EF 50mm f/1.8 STM lens needs a full repair or just a simple adjustment

1. Assess Physical Damage

- Visual Inspection: Check for any visible signs of damage such as cracks, misalignments, or bent parts. If the lens appears lopsided or has loose components, it may require more extensive repair.

- Focusing Mechanism: If the focusing ring feels loose or if the lens extends and retracts unevenly, this could indicate a need for adjustment or repair.

2. Test Autofocus Functionality

- Autofocus Performance: If the lens struggles to focus beyond 2 meters, try switching to manual focus. If you can achieve focus manually, the issue may be related to the autofocus system rather than a mechanical failure.

- Focus Range: If the lens can focus on close subjects but fails at longer distances, this could suggest a simple calibration issue rather than a complete failure of the lens.

3. Check for Internal Issues

- Noise During Autofocus: Listen for unusual sounds when the autofocus is engaged. Grinding or clicking noises can indicate internal damage, which may necessitate a full repair.

- Sticking Mechanism: If the lens feels sticky or does not smoothly transition when focusing, this could indicate a need for cleaning or adjustment.

4. Evaluate Previous Performance

- Recent Changes: Reflect on whether the lens was functioning properly before any incidents (like drops or impacts). If it suddenly stopped working after a fall, internal components may be misaligned.

5. Simple Adjustments

- Manual Focus Test: If you can achieve focus manually, it might just need a minor adjustment. Sometimes, simply realigning or reseating components can resolve the issue.

- Cleaning Contacts: Ensure that the electrical contacts on both the lens and camera body are clean, as dirt can sometimes cause autofocus issues.

6. Professional Assessment

- Consult a Technician: If you are unsure or if the lens shows signs of significant damage, it may be best to consult a professional technician. They can provide a more accurate diagnosis and let you know if it requires a full repair or a simple adjustment.

Conclusion

If the lens exhibits minor issues and can still focus manually, it may only need a simple adjustment. However, if there are significant physical damages, unusual noises, or persistent autofocus problems, a full repair might be necessary. Given the lens's low cost, weighing the potential repair costs against the price of a new lens is also advisable.