Smudge showing up on images. - Canon EOS t6i

[modver110]

This smudge keeps showing up on my images. It is less noticeable when I shoot with f4 aperture. It is prominent when I use f6-f20. How can I fix this? Thank you (canon eos t6i)

[rs-eos · Accepted solution]

This looks like a hair or similar debris near your sensor or perhaps rear element of the lens.

If you have a rocket blower or similar hand-squeezable air blower, use that to remove any debris from the sensor and/or rear element of the lens.

In terms of why the debris becomes more evident at narrower apertures, this is because as wider apertures, the depth of field is narrow and thus the debris ends up being more blurred and less visible.