#### vivian334

##### Member

**What is the projection throw ratio**

projection ratio is actually the ratio of the projection distance / screen width. The smaller the ratio, the shorter the projection distance required to project the same screen width. The projection ratio is the ratio of projection distance / picture width. Regarding the projection ratio standard, it is generally considered that when the projection ratio is less than 1, it is called a short-throw lens; and when the projection ratio reaches 0.6 or less, we usually call it an ultra-short-throw lens.

**The main difference is the distance required to project a picture of the same size .**

A telephoto projector needs a distance of more than 6 feet (about 1.9 meters) to project a 100-inch screen size. It needs a large enough space to use it. The distance required by a short-throw projector to project a 100-inch screen size is about 4.5 feet (about 1.3), which is more suitable for use in conference rooms or classrooms. Ultra-short throw projector, it needs a distance of about 15-20 inches (about 0.5 meters) to project a 100-inch screen, suitable for use in small places such as rooms.

Therefore, when choosing a telephoto or short-throw projection, it mainly depends on the space used. If the projection space is large enough, you can safely choose telephoto projection, but if the space is relatively small, you should choose short-focus or ultra-short-throw projection. Overall, short-throw projection may be more adaptable.