Understanding Depth of Field

lizzyD · Sep 28, 2010

I'm having difficulties figuring out how to properly use my depth of field. I enjoy macro most of all and I'm new to the whole DSLR photography. Ive had my first DSLR for less than a year, I love it but I'm overwhelmed. Can anyone help me?

Overread · Sep 28, 2010

Understanding Exposure by Bryan Peterson - based on your current explaination I strongly recomend this book for further reading on the subject of exposures and controling your camera.

In short you have three settings that make up an exposure - ISO, aperture and shutter speed. If you adjust one value you have to adjust the other two to balance that out within a set scene (ie whilst the light remains the same). Thus if you want to change your aperture you will also have to change either (or both) your ISO and/or shutter speed to compensate.
Your camera manual should explain some of this to you - read up on reading about the meter with you camera body since that will tell you when you are moving away from a proper exposure and are likely to get over/under exposure with your shot.

SrBiscuit · Sep 28, 2010

larger fstop will give you a smaller aperature hole which will make more of the image in focus.

smaller fstop number will give you a larger aperature hole and cause more blurring.

when you change the aperature you must compensate for that with shutter speed (or iso) in order to get the correct exposure.

"understanding exposure" by bryan peterson is a great book that will explain in a very simple way.

KmH · Sep 28, 2010

Depth-of-field (DOF) is controlled in part by the lens aperture. The smaller the lens opening, the deeper the DOF is giving less blur in both the foregrounfd and the background. (DOF is also affected by the lens focal length, the subject to image sensor distance, and the subject to background distance.)

Exposure is controlled by 3 adjustments:

Lens aperture
Shutter speed
ISO

When you change one, like changing the lens aperture to control DOF, you must compensate by changing one or both of the other 2.

With a small lens opening less light is getting into the camera, so generally the shutter is left open longer to make a good exposure. However, with the shutter being left open longer, anything in the scene that moves may wind up blurry in the photo.

If so then the ISO could be increasesd instead of leaving the shutter open longer. However, using high ISO usually means more noise in the photo which when diminishes detail in the photo. A noisy photo is usually bette than having a photo with motion blur.