DSLR Cameras have a wide variety of lenses that can be used.

Chapter 8-Lenses

DSLR Cameras have a wide variety of lenses that can be used.

The camera lens is very important in making great photographs. It controls what the sensor sees, how much of the scene is included, what is sharp or not sharp, perspective and so on.

Focal Length What is it: The focal length of a lens refers to the distance between its optical center and the focal plane (the sensor in a digital camera) when it focuses at infinity; it is measured in millimeters (mm) What does it do: Different focal lengths change the size of the subject at the focal plane. Where is it found: Every lens has at least one focal length (zooms have multiple focal lengths over a range of mm). How does it vary: Most millimeters of focal length magnify the subject size and as they increase, create a telephoto lens. Fewer millimeters make the subject smaller and as they decrease, give a wide-angle lens its focal length. (55)

Zoom lenses versus single-focal-length Two types of lenses lenses (56) Zoom lenses that have many focal lengths and they change as you zoom in and out on the subject Single-focal-length lenses also called prime lenses what have only one focal length

Can take the place of many lenses Can travel light Easy to use-do not have to change lenses Can compose pictures using different angles of view Usually are slower lenses (smaller maximum apertures) (57)

Zoom vs. Prime Lenses Prime lenses offer speed-this lens is a 1.4, a very fast lens. Zoom lenses offer convenience taking the place of many prime lenses with different focal lengths The main advantage of a single-focal length or prime lens is lens speed. They are almost always faster than zoom lenses. They are also usually smaller in size.

Angle of view or relative magnification Wide-angle lens Mid-range lens Telephoto lens (58)

Normal Lens-45-55 mm standard with most SLR cameras. Wide-angle Lens-15-40 mm sees a wider angle of view Telephoto Lens-70-600 sees a narrower angle of view The angle of view decreases as the focal length increases. Wide angle lenses have a great angle of view. Telephoto lenses have a narrow angle of view. Normal lenses have an angle of view like the normal eye would see clearly.

Perspective and focal length One very important use of focal length is to change perspective in a scene. Perspective in a photograph relates to how objects in a scene change in size as they move closer or farther from the camera. Perspective is a relationship of size and distance. By changing focal length and your distance to a subject you can change the perspective in a photograph.

Telephoto view-brings subject closer to camera view. Wide-angle view-shows more of the picture.

Depth-of-field (59) Depth of field is the amount of acceptable sharpness from foreground to background within a photograph. Depth of field affects only perceived sharpness in depth. Perspective deals with size changes in depth. Three things that affect depth of field: Aperture or f/stop Focal length of lens Focusing distance from subject

Depth-of-field explained

Focal length and depth-of-field Shorter focal lengths give a greater depth-offield in an image Longer focal lengths give a shallower depth-offield The closer you are to the subject the more shallow will be the depth-of-field Depth of field Aperture or s/stop Focal length Distance Less Wide Example f2.8 Telephoto or long focal lengths More Small Example f16 Wide-angle or shorter focal lengths Close Far

Using different focal length lenses Wide-angle lenses Landscape photography Travel scenes Connecting subject with surroundings Making scenes look deeper Dealing with small interior spaces Capturing groups of things or people when space is limited Creating dramatic deep space and perspective effects

Using different focal length lenses Mid-range lenses Landscape photography Travel scenes People photography Making scenes look normal; avoiding dramatic effects (documentary style photography) Connecting subject with surroundings

Using different focal length lenses Telephoto lenses Compressed landscape effects Wildlife photography Sports photography Portraits Isolating subject from surroundings and especially background Flattening scenes Making large spaces seem smaller Creating dramatic compressed space and perspective effects.

What is a macro lens? Lenses with this feature can focus very close (less than 8") for taking pictures of small objects at a 1:1 ratio. Many digital camera lenses today have macro capability

Lens features to know Maximum and minimum f/stops-the maximum f/stop is the widest aperture possible with a lens and the minimum f/stop is the smallest aperture that can be set on a lens. Minimum f/stop f16 Maximum f/stop f1.4

Lens features to know Special lens elements-uncorrected lenses have aberrations that cause sharpness and color problems. All camera lenses are highly corrected to deal with these aberrations. Internal focus-lens does not have any moving part that you can see but focuses on the inside of the lens. Image stabilizing lenses-helps to steady your image, built into the lens itself. Tripod socket-you can mount the lens to a tripod, usually on telephoto lenses. Lens hoods-used to protect the lens from unwanted sunlight and from getting scratched.

Lens hood made to fit the type of lens you are using Image stabilizing Lens Tripod mount built into the lens itself

Lens image examples Which images was taken with a wide angle lens? Which image was taken with a normal lens (50 mm)? Which image was taken with a telephoto lens?

All needed telephoto lenses

All needed wide-angle lens

Your Lens It is the most important part of your camera when it comes to taking the image, because it takes the image! Remember to take care of your lens: Keep it clean Do not drop it Take it off and on carefully (D-SLR cameras only) Store it in a safe place Use a filter (D-SLR camera lenses) to protect the lens

Focal Length, Perspective and Depth-of-field