Concept in Definition ABC

The SLR is a type of photographic camera whose main feature is her reflex viewfinder that will make it possible to see the scene through your goal, that is, the image in the viewfinder is generated by the lens itself, avoiding what is known as parallax error (angular deviation of the position of the objects) and seeing the same thing that is going to come out on the Photography what do you drink, the precision of the frame it is calculated at approximately 100%.
There are two varieties of SLR cameras, SLR or single lens reflex and TLR, reflex but with two lenses.

The single lens reflex or SLR boasts 35mm and features a mirror moveable behind your target with a 45 ° tilt that will carry the light up into a prism five-sided that simultaneously projects the image into the viewfinder so that the photographer can observe the.
This is what ultimately allows you to avoid framing errors or parallax errors.
In this case we find the shutter in the body of the camera in front of the film or digital sensor, a situation that makes it easier to change the lens without causing the film to be blurred.

Among the main points in favor of this are the aforementioned precision in the framing, the variety of accessories and objectives that it supports, velocity, the photometry system and the exposition. And among their cons we find that they turn out to be heavy and that you cannot see the moment of taking the photo since just there it is dark.