Thursday, January 27, 2011


 How An Aperture Look Likes?

What Is... Aperture?

An aperture is an opening. In the world of photography, people use the term “aperture” to describe how much light is admitted into the camera. The width of the aperture can be controlled manually by the user, or automatically by the camera. Aperture width has a profound impact on the appearance of the final photograph, and the concept of aperture is often introduced at a very early stage in the study of photography as a result.

The main function of a camera lens is to collect light. The aperture of a lens is the diameter of the lens opening and is usually controlled by an iris. The larger the diameter of the aperture, the more light reaches the film / image sensor.

Aperture is expressed as F-stop, e.g. F2.8 or f/2.8. 
The smaller the F-stop number (or f/value), the larger the lens opening (aperture).

When we look at the technical specifications of a digital camera, one of the very first specification mentioned is its maximum aperture and/or its aperture range.What is 'aperture,' what is a good aperture range, and how is aperture relevant when it comes to choosing a digital camera?

In practice, unless we are dealing with a fixed-aperture lens (many simple point-and-shoot cameras have only one fixed aperture), the aperture of a lens is usually expressed as a range of fstops.

When we read the specifications of a camera, the aperture may be expressed in a number of different ways, the following three being the most common:
  • Maximum Aperture:
Max. Aperture F2.8
This simply states that the maximum aperture for the lens is F2.8.

  • Aperture Range:
Aperture Range F2.8-F8.0
This states the max. and min. aperture, the assumption being that there are standard increments between them.

  • Maximum Wide-Angle and Telephoto Apertures:
Aperture F2.8-3.5 or F2.8(W)-F3.5(T)
This gives the max. aperture for the wide-angle (F2.8) and telephoto (F3.5) focal lengths of a zoom lens.

It is usually not too difficult to figure out that a stated range deals with maximum apertures and not max and min apertures: the mimimum aperture should be quite small at F8, F11, F16 or F22.
A "fast" lens is one that has a large maximum aperture (F2.4, F2.0 for current digital cameras; F1.4, F1.2 for 35mm film cameras).

A Good Aperture Range
My personal preference for a 'good' aperture range is:
F1.8 - F16
F1.8 F2.8 F4 F5.6 F8 F11 F16
This tells us that the camera has an aperture range of F1.8 to F16; the maximum aperture is F1.8, and the minimum aperture is F16.

There are 5 f-stops between the max and min aperture. If your camera's lens is currently set at an aperture of F5.6, closing it by 1 f-stop would mean selecting F8; opening it up by 1 f-stop would mean selecting F4.

F1.8 F2.8 F4 F5.6 F8 F11 F16

How Is A Large Maximum Aperture Relevant?

A large maximum aperture is preferable to a smaller one since it gives the photographer more latitude in the kind of pictures that can be taken.

For example, it is pretty obvious that the larger the aperture, the better our digital camera will perform in low-light situations, since a larger lens opening is able to admit more light than a smaller lens opening.

A larger max. aperture also allows us to use a faster shutter speed to freeze action.
So, let's say the light meter in our digital camera calculates that for proper exposure in that indoor arena, we need an aperture of F4 and a shutter speed of 1/60 sec.


To use a faster shutter speed (say, 1/250 sec.) to freeze action, we have to open up the aperture to allow more light in for that shorter amount of time.

For every shutter speed increment we go up, we need to open up a f-stop of aperture. From 1/60 sec. to 1/250 sec. there are 2 increments, so we open up the aperture by 2 f-stops, going from F4 to F1.8. Note that the camera would give proper exposure at 1/60 sec. at F4, 1/125 sec. at F2.8, and 1/250 sec. at F1.8, since all three aperture/shutter speed combinations allow the same amount of light into the camera.

How Is A Small Minimum Aperture Relevant?

A small minimum aperture is preferable to a larger one since it also gives the photographer more latitude in the kind of pictures that can be taken.

Suppose we want to take a picture of flowing water. As mentioned above, to depict flowing water, we usually want to use a slow shutter speed so that the water blurs. It is this blurring that makes the picture so effective in depicting water motion.

So, let's say the light meter in your digital camera calculates that for proper exposure on a bright sunny day, you need an aperture of F8 and a shutter speed of 1/125 sec.


Well, if we decide to use a slower shutter speed (say, 1/30 sec.), this means that we have to compensate by closing down the aperture to allow less light in.

It makes sense really. Since we have increased the time the shutter remains open to allow light in, we must compensate by allowing less light in to expose the image sensor in that longer amount of time, if we still want a properly exposed picture.

(Self Review)
Aperture is the size of the opening of a lens. The aperture determines how much light will enter through the lens.It is measures by the F stop numbers. The big aperture is small F stop number while the small aperture is large F stop number. For example F1 is wide opening letting in lots of light and F32 is a small opening letting in little light.

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