After not being on these forums for a couple years (too busy and forgot about it) I’m coming late. @abbygeorge In my limited experience, (and I’m sure this varies a lot) some cameras seem to struggle to focus or at least take longer when the battery is lower (not saying ‘low battery’, but at 1/4 or 1/3). My dad had a Nikon point-and-shoot that did that especially badly when in lower light or with a moving subject. Put in a fresh battery, and, presto, the AF works perfect in the same environment. I think my Canon 80D does the same thing, a little, with my 70-300 lens being slightly worse than my 18-135, I think. Anyway, just something you could experiment with sometime. Put in a half dead battery and try some low light, high ISO photos and see how the AF behaves. You don’t need a moving subject, just swing the camera at different objects and see how quick it will focus. Repeat with a fully charged battery and see if there is a difference.