Besides setting the lense to Manual focus, can single point Auto focus be used to focus 'beyond' a foreground of tree branches to infinity? Living in the mountains makes long distance focusing a challenge. Thanks! Canon t7i w/ 55m kit and 50-250mm tele. (amateur)
If we are talking about the phase-detection autofocus (the one you get through your viewfinder), then it is important to know that the actual AF-point is larger in area than the one you can see in your viewfinder. Therefore it would be best to look for a gap that is slightly bigger than your chosen AF-point.
With contrast-detetction autofocus (LiveView), a gap that is as wide as the AF-point should be enough.
Another possibility is to use lenses with a focus-limiter-switch - this feature is most often found on (higher-priced) tele-lenses, such as the
100mm f/2.8 L IS USM Macro, the
100-400mm f/4.5-5.6 L IS II USM, the
70-210mm f/4, etc.p.p.. Lenses with that feature have a dedicated switch that can limit the focus-range; e.g. from 1m-∞ to 5m-∞. That way, the AF will ignore objects in front. However, few of these limiters are designed to ignore mid-range obstacles; they are mainly intended to allow shooting through fences at short distance.
The picture below shows the AF-limiter settings on the
100mm f/2.8 L IS USM Macro - notice that it has three settings (
0.3-0.5m) that are designed to differentiate between macro and non-macro distances. Some/most lenses just have two settings.
Image stolen from GearOpen's Canon 100mm f/2.8 L IS USM Macro review