Trying to track a bird in flight and keep it in the frame when zoomed out to 300mm is extremely difficult, but with the EE-1 Dot Sight it is much easier to do so and I can keep both eyes to boot. As mentioned in other reviews, it is easy to set up and center the dot using two thumb wheels. ( One for up & down and one for right to left.) I also appreciate the thumb wheel that allows you to tighten it in the hot shoe. It is a valuable feature. I once lost a very expensive GPS logger because a slight bump knocked it out of the hot shoe. Although the outside is made of plastic, the side struts and the base they are connected to inside the unit are metal. It actually has a pretty solid feel to it, especially when closed. Just be sure to close it down before putting it in your camera bag or pocket. The only reason I didn't rate it five stars is that if I try to use it while wearing glasses, sometime the lens of my glasses rub against the top portion of the case and knock the dot off center. Same if you wear a hat.