01-24-2018 06:42 PM
Based on your description of this issue we recommend sending it in for evaluation at your earliest convenience.
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01-25-2018 12:17 PM
Is it the "micro motor" version of the EF-S 55-250mm.... i.e., it's NOT marked "STM" (which stands for "stepper motor")?
Micro motor lenses typically DO make some noise when focusing. They're also a tad slower than the quieter, STM version..
In addition, Image Stabilization (IS) typically makes some noises.
If the lens is focusing properly and stabilizing as it should, I wouln't worry too much. But to reassure yourself, maybe take the camera and lens to a store that has the same and compare side-by-side.