Harold Simmons

I aim for about three months and using the fade marker as a cue and swapping sooner after illness. Going longer made the clean worse, so I stick to the schedule.

Diagnose focus versus optics by using single point AF on a high contrast edge, then confirm in magnified live view; if live view is sharp but viewfinder AF misses, adjust AF fine tune or use manual focus and set the eyepiece diopter so the AF markers are crisp. Use a faster shutter at least one over focal length and support the camera to rule out motion blur, and if it still looks soft around f8 across the frame get it checked.