The key to sharp photos
Close up of an eye of elk that is in focus even when zoomed in upon
Eye-tracking on many of the new mirrorless cameras has definitely changed the photography game. These new units are set to lock in on the animal's eye and can stay focused on it as it moves. While this has helped with taking images it still is not flawless. At times it can lose focus or not lock off the start. But why did the camera engineers focus on eye-tracking? Because they know for an image to appear sharp the eyes have to be sharp!
Despite the outer tips of the wings not being in focus, the image is not perceived as out of focus because the eyes are sharp
Regardless of how perfectly focused your image is, if the eyes are not super sharp the entire image will seem blurred and off to the viewer. Vice versa though if the eyes are sharp and in laser focus then regardless of the rest of the sharpness in others areas of the image the viewer will perceive the image as in focus. Therefore getting the eyes sharp and in focus are critical to taking a great photo.
There is more sharpness to this bear in its fur, especially towards the back of the bear. The eyes are not tack sharp giving the viewer the impression in the full image of the bear being out of focus despite the good focus in other areas.
There has been no editing done to this photo. You can see the sharpness of the eyes when zoomed in giving this photo the overall appearance of being sharp and in focus.
To test to see if your images are truly sharp magnify your image to 200% if not 300% and see if the eye still looks tack sharp if it does then you have a keeper! I frequently will check in the field to ensure the eyes are looking good in my images. I zoom in on an image on the LED display and look closely at the eye to ensure I am capturing good photos. If it is not sharp at that magnification then I know I have some work to do. Despite using eye-tracking there are still times when I may not have good sharpness in the eyes. There are a few things that can impact this including light and distance.
Taken in low light at a slower shutter speed the owl still looks in focus despite the wings having motion blur because the eyes are in focus
There is more likelihood of getting sharper images in good light since in low light conditions it is challenging for most cameras to gather enough light to quickly focus. When using eye-tracking if the light is low it may be focused well when it is locked on the eye causing many out-of-focus images. Or even without eye-tracking, the camera will be challenged to get sharp well-focused images in these conditions. The less light the camera has the less sensitive and less accurate the autofocus will be. This may mean your best option is to manually focus. If I am in this situation I often will zoom into the eye of the animal while viewing in the viewfinder and manually focus to ensure instead of trusting the camera.
Another important factor is the distance to the animal. Cameras are more and more powerful and there are many great zoom lenses out there, but the closer you are to your subject the better likelihood of getting sharper images. The eye is not a large target a distance and the autofocus may lock in on an ear or a noise causing the image to appear out of focus. The closer you are to the subject the more likely your camera can discern the eye and accurately focus on it. Unless you are going for a certain effect you should always be trying to focus on the eye, it is the number one key to getting sharp images.