Program mode and aperture

Hi
I was at the beach recently, and was taking pics of the beach and ocean from my hotel balcony during the daytime. My 350D was on Program mode and I was shooting in RAW. My metering is set at Evaluative. Each time I pointed the lens at the ocean, the exposure settings came up as a 5.6 most of the time (along with a high shutter speed). I was a little confused by this because:
1. Why was it picking such an open aperture?
2. If I wanted to try and capture some sharpness of the ocean, I turned the dial to a higher aperture, like f/11. Was this wrong?
(keep in mind that i tried to keep the SS as high as I could, i was using a monopod).

Is it safe to just snap the pic and keep the exposure settings the camera gives you instead of making changes?

I hope I'm making this clear. Thanks.
Ruth

1. In Program Mode the camera uses an algorithm to determine shutter speed and aperture based on the EV level of the scene. If you look in your owner's manual, there's probably even a chart that tells you what shutter speed and aperture the camera will pick for a given light (EV) level.

2. You weren't wrong to change the aperture value to something you wanted, but given the distance you were from the ocean you probably already had more than sufficient depth of field to capture the scene with adequate sharpness.

3. Is it safe? Sure....you're not going to get hurt or anything. Will the exposure be correct? Will the photo suffer from motion blur? Will the photo have adequate depth of field? Those are really the questions have should be asked. The answer to all of those is: "It depends." You have to consider the final settings that you wind up with to answer those questions. Will the shutter speed be high enough to prevent motion blur (otherwise known a camera shake) given the shutter/aperture/focal lenght combination? Will the aperture be small enough (or large enough) to give the appropriate depth of field for the shot you wish to take? Is the ISO low enough to prevent excessive noise in the photo? You have to consider all of those things for the given exposure.

Have you read Bryan Petersen's excellent book Understanding Exposure? If not, do so. I think it will help answer many of your questions. Also he just recently released another book entitled Understanding Digital Photography. I haven't completely finished my perusal of the book, but it also seems like an excellent (if very opinionated) book for beginning photographers.

Mark

Thanks Mark for responding to my question. I guess I was mostly concerned that given my distance from the beach, I was concerned if I was getting enough DOF. With so much daylight, I was surprised that the camera kept it's exposure settings at such a wide aperture. Since I was using a monopod I wasn't so worried about camera shake.
I have read Understanding Exposure but didn't know he had the other out. I will look into that. Thanks again.
ruth

I just wanted to touch on what Mark said about Peterson's book Understanding Digital Photography. This book is great. It is a toned down version of the original, but illustrates very well what needs to be known. The only "problem" I have with his book is that he tells you to use f/22 to "Storytell" but everything I have read shows that diffraction occurs starting around f/11-f/16 depending on the camera. For the $20 or so it is a fabulous book.

Ignore sweeping generalizations about what a specific f/stop will do to DOF. Use a DOF calculator, and you'll be surprised at what settings will get you the results you desire: http://www.dofmaster.c​om/dofjs.html.

If you're using P mode and find that you keep winding in a program shift for each shot, it's easier to switch to Av mode. P mode goes for a standard aperture related to the metered EV - it doesn't attempt to look at the subject (as A-DEP mode does) to work out what DoF should be used.

As jfrancho says, it's worth getting a feel of how DoF will affect your images. If you're not sure what aperture to use, shoot several shots at different apertures - you can look at them later on your computer and treat it as a learning experience. So long as you have sufficient storage with you, the extra shots don't cost you anything and you can always discard them once you're back at your computer.

David

Thank you DavidW. You summed it up perfectly. I'm still trying to find the mode (P, Av, or Tv) where I am most comfortable. Thanks for clearing that up for me.
Ruth

Different modes work better for different shooting situations. If I'm at a family gathering, and taking pictures of kids running around, being kids, I'll turn to Tv mode. I'll set the shutter to a fast enough speed to "freeze" the action. The camera will take care of the aperture. That doesn't mean I don't pay attention to the numbers, though. If the aperture value gets lower than I'd like (resulting in a shallow DOF), I can raise the ISO by one stop. If I'm out shooting a portrait, I'll use Av mode and set an aperture value that will give me the DOF I want. If I'm handholding, and the shutterspeed gets too slow (< around 1/focal length), then I can raise the ISO. If I'm shooting with a flash as a primary light source, I use M mode. I can set the background exposure with the camera controls for shutter and aperture (1/80 @ f/8 ISO 200 seems to be a good starting point for indoor shots) and control the subject exposure with the FEC function. I often leave my camera in P mode at ISO 400 when in storage. This seems to be a good general setting for those, "Quick! Get the camera, you gotta see this!" moments when aliens land in your back yard. I also like Av mode for landscapes, combined with the AEB (Exposure Bracketing) feature. Sometimes for big scenes with lots of dynamic range, the camera's metering gets tricked into exposing for som,e element in the frame that you didn't think was as important as another. A classic example is the landscape with the blown out sky, when you really wanted the cloud detail. Or just the opposite, a dark mountain with a nice blue sky. Auto bracketing in Tv can be very useful for portraits when you aren't sure what aperture will give you the desired DOF. Just work slowly through each feature and mode on the camera. Pick one, and read the section in the manual a few times, and practice with the camera. It'll all come to you naturally with practice.

Thanks jfrancho for that detailed explanation. I have read a lot about exposure and their affect, and sometimes it makes sense when you read it, but then when you put that camera up to your eye, the mind goes blank. Like you said, practice then more practice. Just when I think I have it all down, the camera decides to do what IT wants to do! Deciding which adjustments to use is the trick. I pay more attention to my histogram now, but that isn't going to tell me how the pic is going to look for DOF. I do take numerous pics at different exposure settings, and check later. Quite frankly, I couldn't really tell the diff between a f/11 and f/16 when looking at the pics of the ocean. But they came out nice anyway. One thing I learned tho here, is IF I have to do a lot of 'dialing', then it's time to switch the mode.
Thanks, Ruth

You're welcome. Your right, an f/11 or f/16 setting probably won't make much difference, especially if you are using a wide angle lens. The only difference in DOF would be how close to the camera the range of sharpness extends, since at both settings, DOF probably extends to infinity.