Digital Photography – Exposure Settings

    Published: 06-16-2009
    Views: 18,249
    Commercial photographer Michael Stewart discusses the basics of digital photography including how to understand the exposure settings.

    Michael Stewart: Hi! I am Michael Stewart. I am a digital photographer and I am here teaching simple digital photography. In this segment, we are going to talk about exposure. There are three elements I would like to talk about here. The first is ISO, that is the sensitivity of the sensor. The second is aperture, that is going to affect your depth of field in the image. That is the amount of the image that is in focus. And the third is shutter and the shutter speed is going to affect none of motion blur that you have. All three of these combine to make up the exposure of the image. You want your exposure to have good highlight and shadow detail. There is a histogram that will show this in exposure. And so, the way that you combine these three is make that up, it is going dictate what the image looks like. Lets start with ISO. ISO is the sensor's sensitivity to light. The higher you turn the ISO up in numbers from 400 to 800 to 1600, the more sensitivity you have to light. But also ,for more noise you put into the image. Noise is color and basically bad pixels that aren't supposed to be there on the image. When you put more electricity into the sensor, you get more photons that are jumping around and landing in the wrong place and causing bad pixels. So the higher the ISO, the lower the image quality. Some of that noise can be removed later. But we don't want to have to do that to images. The second thing is aperture. Aperture is very important to the amount of depth of field. Some of these cameras with small sensors. It is very hard to get a shallow depth of field, meaning that everything is always going to be in focus. This is fine for a lot of images but for portraits and for macros of flowers that type of thing, we don't everything in focus. We want to focus in on the subject only. So with the aperture, the wider the aperture, the more light you let in and the shallower the depth of field. The smaller the aperture, the less light you let in and the more depth of field that you are going to get. This has to combined with a shutter and an ISO that are going to work. Now the shutter speed controls moving subjects. Okay, if you have trees that are moving, then you really don't want to use lower than a 60th or a 1125th of the second for shutter speed. If you do, you are going to have blurred action. If you are shooting something like race cars, you need a 250th or 500th. Now, may be your camera doesn't have settings for this but it will have settings for sports and action and portraits. That is what those settings are doing. They are picking the combination there that you need to get the look that you want for those type of images. So to review the combination of shutter, aperture and ISO are going to create the correct exposure. Correct exposure is going to give you a good histogram that has both highlight and shadow detail.

    Next, we are going to talk about Digital Asset Management and how you can save your files for the long term.