Photography lessons

[scorps]

I cant find the manual for my camera, its not written in booklet form it was on a CD.....anyway i would like to know more on how to get the most out of my camera rather than just take the pic i see on the viewing screen and i have a few q's to ask.

 

What do the following mean and when to use them.

 

EV

 

ISO: 150 AUTO 150/80 150/200 150/400 150/800 150/1600 150/3200

 

Photo Size: 12m 10m 9m 8 5m 3m 1m

 

Image quality: super fine/fine/normal

 

Drive: single/continuous/motion cap/AEBPhoto style 8 settings

 

As there are a few members on here that know their stuff maybe we can discuss 1 subject a day.

 

[Sagitar]

I cant find the manual for my camera, its not written in booklet form it was on a CD.....anyway i would like to know more on how to get the most out of my camera rather than just take the pic i see on the viewing screen and i have a few q's to ask.

 

What do the following mean and when to use them.

 

EV

 

ISO: 150 AUTO 150/80 150/200 150/400 150/800 150/1600 150/3200

 

Photo Size: 12m 10m 9m 8 5m 3m 1m

 

Image quality: super fine/fine/normal

 

Drive: single/continuous/motion cap/AEBPhoto style 8 settings

 

As there are a few members on here that know their stuff maybe we can discuss 1 subject a day.

 

Most of that stuff relates to a specific camera so it would be useful to know which camera?

 

But let's start with EV which is common parlance and means Exposure Value.

 

You can vary the way in which film (or a digital sensor) is exposed to light in three ways:

1) by increasing the diameter of the aperture through which light passes to the inside of the camera

2) by varying the length of time that you allow light to pass into the camera

3) by varying the sensitivity to light of the film (or digital sensor)

 

The actual diameter of the aperture will vary with the size of the film that it has to cover but to get to a universal measure we use a a value that takes account of the aperture diameter and the film size. We call this number an f value or a "stop" size. A typical series of f values would be f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32 etc. This is not the only series that is used, but it is a common one. A change of one "stop" e.g. from f/2.8 to f/4 will halve the amount of light falling on a unit area of film. A change in the opposite direction e.g. from f/11 to f/8 will double the amount of light falling on a unit area of film. The variation of stop size is normally achieved by the use of an iris diaphragm but other methods are sometimes used. There is sometimes confusion about the smaller f number letting in more light, but notice that it is written f/2. The two is below a divide sign so the bigger the number and the smaller the value. The f number is actually the ratio of the focal length of the lens to the effective diameter of the aperture, but you needn't worry about that.

 

The length of time for which the film is exposed to light is normally controlled by a shutter of some kind. For slow speeds it may be calibrated in minutes or seconds, for faster speeds we use a series such as 1/2sec, 1/4sec, 1/8 sec, 1/15sec, 1/30sec, 1/60sec, 1/125sec, 1/250sec, 1/500sec and then for higher speeds in 1000s of a second. Again you can see that one step on the speed scale either halves or doubles the amount of light falling on a unit area of film.

 

Finally, the sensitivity of the film is measured by using an ISO (International Organisation for Standards) value. If you come across old film it may use a different standard such as ASA, DIN or Scheiner, but the principle is the same, there is a doubling of sensitivity for each scale change. i.e. 400 ISO is twice as sensitive as 200 ISO etc.

 

The practical implication is that if, say, the intensity of available light reduces to a half of its previous value, you can accommodate the change by: increasing the stop size, or increasing the time that the shutter is open, or by increasing the sensitivity of the film.

 

Since each of the three variables can achieve the same effect, it is convenient and useful to speak of them all in the same terms. We call the change achieved by altering one of the variables by a single unit, a change of 1 Exposure Value.

 

So, you can increase the EV by 1 by increasing the stop size by one step, or changing the shutter speed value by one step, or changing the film sensitivity by one step.

 

You can keep the EV constant by increasing one of the variables by one step and decreasing one of the others by one step. And so on.

 

Now, I must complicate things a bit by acknowledging that modern cameras allow changes of aperture, speed and film sensitivity smaller than 1EV. Typically a decent camera will adjust in units of only one third of a stop, but the principle is the same.

 

EV is most commonly used on modern cameras when dealing with exposure compensation. i.e. you can use the compensation setting to achieve a change of exposure value without fiddling with shutter speed or stop size. Consonant with my previous sentence, exposure compensation will typically allow changes of 1/3EV.

 

Some years ago there was a move to use exposure values directly on cameras and you will still find EVs on light meters. Using this convention, 100 ISO with 1/250sec at f/2 gives an EV of 10. But of course EV = 10 can be represented by an infinite variety of the three variables as long as you increase one and decrease one of the others to match.

 

Well you did ask . . . . . . .

[Rich]

Excellent reply there especially for 1:30am!!

[scorps]

I did ask....i just need to understand in practise form.

 

As said in a previous post my digi cam is a Samsung ST45.

 

Anyone for a photography walk/meet taking pics as we go