Hello again everyone. This is Kay's assistant, Joseph. In today's tip we will look at the third (and last) technical area of your camera equipment that a little knowledge about will serve you well:
!!!!!Lens Aperture, Shutter Speed, and Depth of Field!!!!!!
The aperture of a camera lens is the size of the opening that allows light through the lens to strike the film (or digital sensors) when the shutter opens. It is also called the f-stop, abbreviated f/. Every lens has a single, or multiple aperture settings. Almost all good compact digital cameras and SLR lenses have multiple aperture settings. In the days before digital, you turned a ring on the lens to change the aperture setting. Now most cameras have a button or thumbwheel you can use to change aperture settings (usually the camera has to be in Manual, or "A"-Aperture Priority Mode to make these changes).
Here is a picture showing the size of some common lens apertures:
!!!!!Yes, you are correct if you noticed SMALLER f/ NUMBERS MEAN LARGER APERTURE OPENINGS!!!!
So we call f/1.4 a LARGE APERTURE, and f/8 is a SMALL APERTURE! There are also f/11 and f/16 (very very small) apertures. It is cusomary to label a lens with the largest aperture opening the lens is capable of (remember that means the smallest f/ number). For example if your camera or lens says 55mm f/2.8, then it is a 55mm focal length lens (we talked about focal length in Tip 4) with a maximum aperture of f/2.8.
If you have a zoom lens, it will probably have two aperture numbers listed. This is because as the lens becomes longer, it restricts the maximum aperture the lens can have. For example, my Nikon 18-55mm lens has the following written around the front of the lens:
AF-S DX NIKKOR ED 18-55mm 1:3.5-5.6
This means the lens is a 18-55mm focal length zoom lens with a maximum aperture of f/3.5 when the lens is at 18mm and a maximum aperture of f/5.6 when at 55mm. As a rule of thumb, if you want your lens to have a wider maximum aperture opening, be prepared to pay a lot more!!
Ok Joseph, But What Does This Mean to Me?
1. Shutter Speed:
Large apertures require less exposure time to get your picture. If you are shooting moving objects, then you need faster shutter speed to capture the image without blurring. Smaller apertures, because the let less light through, require longer exposures and slower shutter speeds. Now, for real estate photography, houses and furniture are not known for moving very fast, so you rarely have to worry about motion blur. BUT REMEMBER THAT AT SHUTTER SPEEDS UNDER ABOUT 1/60TH OF A SECOND YOU MAY ENCOUNTER CAMERA SHAKE IAND BLUR IF YOU ARE NOT USING A TRIPOD.
The exact shutter speed where camera shake depends on how steady your hands are and what focal length the lens is at. Telephoto lenses require faster shutter speeds to avoid camera shake and wider angle lenses can handle slower shutter speeds.
2. Depth of Field:
Depth of field is the name for the distance range area of your picture that will be in focus. This is directly related to the aperture setting. Large apertures, although they are great for letting a lot of light into the camera so you can use a faster shutter speed (good for low light shots) HAVE NARROW DEPTH OF FIELD.
This means that only a small range in front or behind the object you are focused on will be in focus. Any objects outside the depth of field will be blurry.
Smaller aperture settings, though they require longer exposures and thus slower shutter speeds, HAVE A WIDE DEPTH OF FIELD. This means much more of the picture will be in focus, even if you didn't exactly focus on the object you wanted.
It is easier to show all of this with a few pictures. I have called in a few members of my home office team to assist....
Here is the Home Office Team shot at 18mm f/11. The camera was focused on Tigger. No flash was used and the exposure time was...30 seconds! Yes, I used a tripod. Notice at f/11 how pretty much everything from Mickey to the chair is pretty much in focus. That is the depth of field.
Again I left the lens at 18mm but used a flash, which sets the shutter speed at 1/60th of a second. The aperture was set at f/3.5. I focused again on Mickey's face. Notice at f/3.5 how now Tigger is no longer in focus, even though he is only 18 inches behind Mickey. This is a narrow depth of field.
Now I zoom to 55mm, set the lens aperture to f11, which results in a 9 second exposure (tripod in use). The camera was focused on Ninja Sock Monkey. Notice how the depth of field changes as you change the focal length. Mickey is out of focus, Tigger is 3/4 in focus, and Sock Monkey is completely in focus. The area behind Sock Monkey gradually loses focus as you move back.
So hopefully you now have a better grasp of what is meant by lens aperture and depth of field. In the next Tip we will leave the technical areas of your camera and talk about:
UNDERSTANDING LIGHT: WHAT YOU THINK YOU SEE IS NOT WHAT YOU GET
I will leave you with a few pictures to show how depth of field can be used in your photography:
You can also check out my personal Photoblog of McKinney-