Shutter speed = fraction of a second that the media (film, digital camera sensor, etc) is exposed to light

F-stop = diameter of the opening in the lens that the light shines through.

F-stops are expressed as the focal length of the lens divided by a standardized number. There is an aperture inside the lens which closes down as the picture is taken. If it closes down to say, f/8 that means the diameter of the aperture equals the focal length of the lens divided by 8. So if you had a 50 mm lens at f/8 you would have an aperture with a diameter of 6.25 mm. The bigger the number, the smaller the actual opening.

Depth of field is controlled by the aperture. Think about if you squint your eyes and really try and look at something. You get a smaller hole which the light has to filter through and you can see more sharply, but it's darker. Same concept works with a camera. Using a higher f-stop (i.e. smaller aperture diameter) is in effect making the camera squint. More stuff is in focus, but less light makes it inside. Depth of field is basically the distance away from the camera within which stuff will be in focus. So if you have like 3 feet depth of field, you will have a window of 3 feet front-to-back that will be in focus. Focusing the lens moves that window closer or further away from the camera.

Keeping with that, if you use a higher f-stop, you need a slower shutter speed. Since the higher f-stop lets less light into the camera, the shutter needs to be open for a longer amount of time.

As for taking pics of sunsets, your spot meter setting is really helpful. The normal light meter on most cameras kind of takes an average of the whole scene and tries to get an exposure setting which will even it all out. With a sunset you have the relatively bright sky and the ground doesn't have much light shining directly on it. So if you use a light meter setting which takes the whole scene into account you end up with too much light going into the camera to make the sky show up, and not enough to make the ground show up.

You want the pics to look like the ones ManInCamo posted above, so you use the spot meter. This can be done with the camera still on auto. A spot meter is what it sounds like, it only takes a light reading in one spot, usually the center of the frame. To use the spot meter to expose for just the sky, you do the following. First, of course, you have to set the camera to use the spot meter. I don't have your camera, so read the manual. To take the picture, you point the center of the frame at the sky (or whatever else you want to limit the exposure to) then push the shutter button in halfway. As long as you keep the shutter pushed down half way, the camera will maintain what's called AE lock. This means that the exposure info is set for what the meter read while you were pointing it at the sky. While you have the button held down, re-frame the shot however you like. Make sure not to let go of the button! When you get the frame set up how you like, push the shutter down the rest of the way and voila, you have a picture that is exposed for the sunlight.

 

How much did you get the A80 for? I saw it go for like $180 last week, thought about picking one up for backup.

 

are you sure it was the A80 and not the A60? I paid about $375 with a free 128 mb memory card at Circuit City.


thanks for the info Fatbooty.


I took some sunset shots today. I didn't get a chance to use the info on spot metering since i just read it but I did mess around with the preset white balance settings in the camera. This is an example of what I was able to capture. The rest of the pics are in the link from my last post. All Critiques welcome.

 

high res pic, yay!