f-stops anyone?

Question

I need a detail explanation on f-stops please,or can anyone direct me to a free online tutorial website on the subject,thank you

Answer 1

F-stops are a numerical system for the aperture (or size of the opening through which passes) in a lens. The wider the opening, the lower the f-stop number, and the more light passes through. The narrower the opening, the higher the f-stop number, and the less light passes through. Smaller f-stops require longer exposure times, and lower f-stops need less time, since there is more light passing through the lens. F-stops also affect depth of field, but that's another story :)

Here's a pretty good article that gives some examples:

Answer 2

f-stop is a measurement of how large (or small) the aperture is. (the aperture is the opening that allows light through the lens onto the film or digital sensor)

Common f/stops are 1.4, 2, 2.8, 4, 5.6, 8, 11, 16
One can see that there is a simple pattern: Every other f-stop is half or double the ones next to it.

F-stops are actually a ratio, and this is why f-stops are the same for most lenses. The ratio is: (lens focal length / aperture diameter)
Thus, at f/2, a 50mm lens has to have a 25mm aperture opening. This explains why telephoto lenses which have very low aperture capability (like f/2.8) must also be very large in diameter. In addition, remembering this ratio keeps in mind that the lower the f-stop, the larger the aperture opening and thus the more light that comes in.

There are two main reasons for the use of f-stops:
1. Because of film or digital sensor sensitivity, f-stops are used to allow more or less light onto the film/sensor. Thus, by picking the right f-stop (along with shutter speed), one can achieve the proper exposure and get a nice photo that is not too dark or washed out.

2. Because of the nature of light, different f-stops have different depths of field. Depth of field is the area that is in focus. For example, many photos have the main subject in focus, but the background is blurry. This is an example of a "shallow" depth of field, where there is a limited distance in which things are in focus. This is achieved using LOW f-stops, with the lower the f-stop, the shallower the DOF. Conversely, if one wanted to make sure everything was in focus, you would try to use a higher f-stop.

Answer 3

The F-stop is the size of the opening in the lens related to its focal length. It is adjusted by a diaphragm just like the iris on Stargate SG-1 (and is also called an iris).

It determines how much light reaches the film (for exposure) and
The depth of field (how much in front or behind the subject will be in focus).

F-stops are generally variable, but some special and/or old lenses just have one.

Ranges of f-stops are: 1.0, 1.4, 2.0, 2.8, 4.0, 5.6, 8, 11, 16, 22, 32, 64, 128

Normal ranges are 4.0-16.

The smaller numbers let the most light in and have the smallest depth of field. They are also more expensive because they are harder to make.

Each change in f-stop lets in 1/2 of 2x the light of the f-stop next to it.

This is used together with the shutter speed to the the desired effect as each halving or doubling of shutter speed also lets in 1/2 or 2x the light.

Intermediate focal lengths are common, such as f 6.3.

Some lenses (zooms) have a variable f-stop as it's cheaper to make the lenses that way. It will indicate f3.5-f5.6. The f3.5 will be on the widest angle and the f5.6 when it is zoomed in.

Lenses are usually sharpest at about the middle range of their f-stop range. For a f4-f16, around f8 would usually be about the sharpest.

So, the ideal lens f-stop would be begin at f1.0 and end at f32 and would also start at about $1000.00. By starting at about f1.8 or f2.0, you cut about $950 off of that price.

Don't know about a tutorial.
I guess wikipedia would be a good place to start.
There many variations on f-stops, and things that one might be more usefully in a particular case or another - so that's it in a nutshell.

Answer 4

The lens consists of the aperture - the adjustable hollow that shall we the easy by to the movie or sensor. you could superb take care of the aperture in the lens (none in the digital digital camera), besides the undeniable fact that the digital digital camera (somewhat usually) can communicate with the lens to set the aperture in it. from time to time you will have the flexibility to get a instruction manual len (lolder ones extra often than no longer) and those is often adjusted by hand - as quickly as extra on the lens. The f quantity denotes how open this aperture is, and how a protracted way open that's. This levels from 0 upwards with 0 being completely open. The smaller the quantity extra often than no longer the better great lens it is going to be (greater glass lens in it so on a similar time as aperture is massive open there is far less distortion from the lens). Smaller f quantity helps for a shorter focal era - that exhibits that the bits in the image which would be in consciousness are closer jointly - so properly for close to up pictures and so on. So lens has probable f/a million.4 on the least on hand, besides the undeniable fact that the digital digital camera widens the aperture in the lens to f/8 or something as required by its prgramming. placed the lens on and the digital digital camera will could do the rest As an aside - you will have the flexibility to get adaptors to place distinctive makes lenses on a digital digital camera physique (probable low-priced), and of direction if yet another make the digital digital camera can no longer communicate to the lens, you could set the digital digital camera to f/0 and then it is going to assume the aperture is completely open and verify the exposure time common on the gentle it senses besides the undeniable fact that than what it assumes will come by the lens on a similar time because it closes the aperture because of the fact it takes a photograph. something like that as properly.

Answer 5

The term f-stop is a relative measurement of the aperture of a camera lens. The aperture (or iris) changes size to allow for changes in depth of field, which is how much of the photograph is in focus. A low number indicates a large aperture size. A large aperture (f/2.8 for example) allows for a lot of light to hit the film plane so shorter shutter speeds are needed. A large aperture is needed to stop action in sports or to film in lower light conditions. A small f-stop (f/22 for example) brings more of the picture into focus, good for landscape shots. Less light makes for a slower shutter speed.

Answer 6

Aperture is described in terms of f-stops, as you know. It is the ratio between the focal length of the lens and the actual diameter of the lens opening. For instance, an f/2 on a 50 mm lens is 25 mm in diameter while an f/16 on the same lens is just over 3 mm in diameter.

Here's a decent explanation of what this all means:

http://www.photoxels.com/tutorial_aperture.html

Answer 7

there are two adjustments on a manual camera. the F stop controls the length of time the aperture is open. The other is the aperture setting this controls the size of the aperture opening the lower the number the brighter the light the smaller the hole. The depth of field is controlled by the focus. The speed of the film should match the amount of light you will use in the photograph. the higher the number on the film the brighter the light you have to have. 200 speed for inside and 400 or higher in the outdoors. manual cameras have fallen out of favor with the digital age. But you can get them cheaply and take some great photo's. There are tons of sites with more information than i have given.just google your topic.

Answer 8

f stops are easy...
as the number increases so does the depth of field and the exposure time

decrease the f stop and you have less depth of field and shorter exposure.

Answer 9

WHAT your doin a detailed explation on full stops(.)?
thats reallllly wierd coz theyre just dots at the end of sentences.