choosing the correct aperature & shutter speed?

[ISI_Stang06]

Recently i got a chance to skim through Understanding Exposure and get a feel for the relationship of aperature & shutter speed.

whenever the author talks about choosing the right relationship between the both, it seems like he has a tool to tell him which settings to choose, so my question is...

is there a function in my camera to help me determine the correct aperature & shutter speed for the upcoming photo i want to take, or is it only by trial and error and taking several shots in different settings to find the proper one?

 

[reg]

Your light meter.

-2 -1 0 1 2
------|--------

etc.

 

[Overread]

That will help pick the right settings for a correct exposur - but you need to keep some settings fixed - otherwise you will get in a right muddle.
For example you have your ISO - which you can often keep mostly stable - lets say its a bright day and you are doing a portrat, so light is good, a low ISO can be used like 100.
Then I consider my aperture - in other words how much depth of filed I want in the shot - I might pick f4 for example. Now I have my fixed ISO and also the depth of field I am after - so the variable value is shutter speed.
I mostly work in aperture priority mode as the camera reads its meter and sets the shutter speed on its own - however its important to check the shutter speed; too slow and blur might appear - to counter that boost the ISO to a higher value or lower aperture (which will of course change the depth of field - so I tend to change this only after my ISO is as high as I can risk it.)

After that its lots of experimentation, practice and reading the works of others to start building a general understanding of different effects under different lighting

 

[ISI_Stang06]

thanks guys, really helping me out.

but a question on the light meter: the setting considered perfect is when it reads 0? because i dont really know how to read it?

 

[Overread]

At 0 the camera judges the shot to be well exposed - so "perfect" yes. But of course what metering mode you use will affect this judgement, further sometimes you want under or overexposed areas. Further many find that in direct sunlight the camera gets confused and can lead to blowouts (overexposed suntouched areas) and the best thing to do is to underexpose by up to one stop. (-1),
Best thing is to learn to read the histogram on your camera - if the histogram shows all the bars to the left then your shot has underexposed areas, all to the right and its overexposed - all in the middle is ideal and often its best to try and lean a shot to the right more to have more light and thus details to work with - whilst of course keeping it from hitting the lefthand side

 

[William Petruzzo]

Best thing is to learn to read the histogram on your camera

Extremely good advice.