Difference Between Aperture and F-Stop

Aperture vs F-Stop

Aperture and F-Stop are two important aspects in photography. In optics, and students of photography will appreciate this, f-number, also called as f-stop, refers to the diameter of the entrance pupil in relation to the focal length of the lens of the camera. For a layman, f-stop is the ratio of focal length and diameter of the lens. It has great significance in photography, and in general is a number that reflects the lens speed.

Let us first see what is Aperture. It is the size of the opening in the lens when the picture is being taken. When one hits the shutter, a hole opens up that controls the amount of light going in. This light allows the sensor in the camera to capture a glimpse of the scene that the user wants to capture. Aperture is often measured in f-stops. So, speaking frankly, f-stop tells us how big the opening in the lens is when the picture is being taken.

Larger f-stops mean that lens has a smaller opening, while small f-stops mean that the opening is large. Most common f-numbers are f/2 to f/22. f/22 means a very small, almost hairline opening, whereas f/2 denotes a large hole. Lens is always wide open; it is only when the shutter is pressed that lens blades come out and cover the lens making it as small an opening as you desire.

Photographers tend to talk about apertures and f-stops almost interchangeably. The only thing to keep in mind is that the two are inversely proportioned so as f-stop goes up, the aperture size goes down and vice-versa.

Reducing f-stop has three effects:

• It allows more light to go in, thus increasing the exposure

• Decreases the depth of field, making the background more blurred

• Overall sharpness of the image decreases