Aperture/focal length/ISO

[DarkFalcon]

Aperture


There are a few set sizes for the aperture, those are the following:
1, 1.4, 1.8, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32 etc. They are commonly referred to as f-numbers, and are then written like f/5.6 for example. Not all cameras/lenses can use as low numbers as 1.4, many start first at 2.8-4.

1/aperture opening size + 1/shutter opening duration = 1/ISO
f/stop no. + shutter speed = ISO

when the aperture opening size area is decreased by n times (linearly 1, 2, 3, 4, 5....), the diameter is also decreased by a per-calculated protocol in which the denominator is the no. of times the diameter is decreased (if i didn't remember wrongly it goes f/1, f/1.4, f/2, f/2.8, f/4, f/5.6 ....). so while the aperture opening decreases (less light in), the f/stop number increases (less light in). note the reverse relationship.

Here a picture of opening lens f-stop
http://i35.photobucket.com/albums/d164/clavinpan28/fstop.jpg

[DarkFalcon]

focal length

Camera lenses are complex critters. In the case of a single element equi-convex thin lens, it's easy to measure focal length. You focus a point at infinity, and the distance from the center of the lens to the focal point is the focal length.

Camera lenses are categorized into normal, telephoto, and wide angle, according to focal length and film size. A normal lens is one that covers the film with a field of view that corresponds approximately to that of normal vision. A normal lens for 35-mm film has a focal length in the vicinity of 50 mm. A telephoto lens, as its name implies, acts like a telescope to magnify images... Thus a 200-mm telephoto lens for use with a 35-mm camera gives a 4 x magnification over the normal 50-mm lens."

[DarkFalcon]

ISO

Digital cameras do not use film but use image sensors instead, the ISO equivalent is usually given.

What ISO denotes is how sensitive the image sensor is to the amount of light present. The higher the ISO, the more sensitive the image sensor and therefore the possibility to take pictures in low-light situations.

Most camara have a ISO

100,200,400,800

Suppose your digital camera's light meter warns you there is not enough light to correctly expose a scene.

Remember it mean you must use a extenal or internal flash. suppose again it's not allowed (like in a concert or indoors recital).
Need to use a higher ISO. Set on "ISO Auto" mode, your digital camera will automatically select a higher ISO. Otherwise, you can manually select the next higher ISO and see if the increased sensitivity allows you to obtain a correctly exposed image

Some Digital camera only can use ISO up to 100,200,400.
For DSLR or SLR ISO can be set 100,200,400,800

More to come on my tip.....
Thanks you for reading

[Hendri]

good info , thanks for sharing :)

i learn something new now.

[GrandePunto]

Bro...thanks for sharing