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Copy of Com 2235 Photography Lenses
Transcript of Copy of Com 2235 Photography Lenses
Focal Length Ring
The focal length ring determines the depth of field and the length of the lens. A shorter lens is good for close up objects while a long lens is good for objects in the distance.
A lens mount is an interface between a camera body and a lens. It is confined to cameras where the body allows interchangeable lenses.
A lens is used with a camera body to make images of objects on photographic film or other media capable of storing images. There are many different types of lenses like Macro, Telephoto, Tilt-shift, and Fish-eye which are only a few examples.
How a lens focuses on an image:
The angle of light entry changes when you move the object closer or farther away from the lens and focuses on the subject.
There are many different filters. A UV Filter protects the glass on the lens because if you drop the lens, it is cheaper to replace the filter than the lens. While other lenses can alter colour, provide diffusion, control contrast or have a polarizing effect.
The aperture ring is located on the outside of the lens usually behind the focusing ring, which is linked mechanically to the diaphragm to control the size of the aperture.
The aperture is a device that controls the amount of light through an opening. The aperture is the unit of measurement that defines the size of the opening in the lens that can be adjusted to control the amount of light reaching the film or digital sensor. The size of the aperture is measured in F-stop.
One of the most common camera lens parts on any camera lens is the focus ring. This is a ring on the lens body which moves the elements inside the lens. By adjusting the position of the glass elements, the image produced by the lens can be brought into clear focus.
The focal length is a measure of how strongly the system converges or diverges light. A system with a shorter focal length has greater optical power than one with a long focal length.
Image Stabilization techniques
Tripods, monopods, beanbags, gaffer tape, gorilla pods, and clamps all stabilize the camera to help you be able to get an image in clear focus by steadying the camera.
Characteristics of lenses and their application
The F-stop System
An f-stop is the ratio of the focal length of the lens to the diameter of the aperture. Depth of field refers to the range of distance that appears acceptably sharp. Aperture and focal distance are the two main factors that determine how big the depth of field will be on your camera's sensor.
There are two ways to describe the qualities of depth of field - shallow or deep Depth Of Field. Shallow is when the included focus range is very narrow, a few inches to several feet. Deep is when the included range is a couple of yards to infinity. A small f/number corresponds to a larger or wider aperture size, which results in a shallow depth of field; conversely a large f/number results in a smaller or narrower aperture size and therefore a deeper depth of field.
Applying Depth and field
Correct cleaning and handling techniques for your camera
To clean a lens, use a small drop of lens cleaning solution and a clean microfiber cloth and gently clean the lens surface in circular strokes.
When not using the lenses, put covers on both ends of them to keep dust and dirt off of it.
While changing lenses, its important to turn off the camera and have the lens caps ready to put on both of the lenses you're changing. By keeping your camera pointed down while changing lenses, you help prevent dust or contaminants from falling into the camera body, and encourage any that are already there to fall out.
Wide Angle Lens
Tilt Shift lens
Demonstration Of Different Lenses
It’s extremely versatile with many applications. A standard lens is perfect for recording fine definition, such as close-up and still-life work. It’s also widely used for portraits.
Many standard lenses are also very fast, with maximum apertures typically between f/1.2 and f/2.0. This feature means they can easily be hand-held and also produce beautiful backgrounds.
A zoom lens is a lens which the focal length can be varied, as opposed to a fixed focal length lens. A Zoom lens is one that maintains focus when its focal length changes.
A teleconverter is a secondary lens which is mounted between the camera and a photographic lens. Its job is to enlarge the central part of an image obtained by the objective lens.
A tilt–shift lens uses two different types of movements: rotation of the lens plane relative to the image plane, called tilt, and movement of the lens parallel to the image plane, called shift. Tilt is used to control the orientation of the plane of focus and enhances the part of an image that appears sharp. Shift is used to adjust the position of the subject in the image area without moving the camera back.
A macro lens is an important for getting close-up photos and great at details.
Wide Angle Lens
Wide-angle lenses are the ideal choice for landscapes, architecture, interiors, and group portraits because of their wide perspective and the ability to include more of the subject in the frame. Wide-angle shots have a much greater depth of field and angle of view compared to standard lens shots. Sometimes images can become cluttered with too much included in the frame.
Long telephotos are all about magnification of subjects that are difficult to get close to – most typically wildlife and sport events.
Beanbags are good for when using a tripod or monopod is impractical because you can rest your camera on it on uneven ground.
A gorilla pod is a small flexible, tripod that can wrap around objects to stabilize the camera. (above)
Relationship of focal length to image size
Focal length and magnification are related by the simple equation:
Focal Length X Object size
--------------------------------- = Image Size
Image size is the actual size of the object at the negative or sensor surface. If you wanted to take a picture of an object that is 5 feet tall, using a 50mm lens, from a distance of 10 feet. The actual size at the negative or sensor surface would be: (convert everything to mm)
(50mm) X (1524mm)
---------------------------- = 25mm
The depth of field affects the composition of this photo by keeping the point of focus on the details in the bricks in the ground and the curvature of the school. The background is slightly blurred and doesn't provide as much detail as the foreground.
The depth of field affects the composition by focusing on the cup and the corner of the fence and making the fence get smaller because of the fish-eye lens. It works for this image because the fish-eye lens brings the cup forward to make it stand out.
Everything is in focus in this photo and I enjoy how the lens curves the top of this photo and makes it look round. An area of challenge I think would be is positioning the pile of snow in the middle of the picture. I could have positioned it so it was more interesting.
The depth of field works for this image because it is a landscape and it would be difficult to have any part of it out of focus.
I think a wide angle lens was a good choice to capture this image because I like the wind blowing her hair and having the background out of focus. This composition works because she is positioned well with the sun behind her.
This photo has a deep depth of field because most of it is in focus and it affects the composition because it would be difficult to have a shallow depth of field.
Since I was far away from this tree, I used a telephoto lens to zoom in on the trunk and branches. This composition works for this image because I wanted to have the thick, dark part of the tree to draw your eye. It was important to use this lens because it was impossible to use any other lens to capture this image from far away.
The depth of field affects the composition of this photo by only having a small portion of the image in clear focus. I used the zoom lens because I was far away from this sign and I like how you can't read the other signs.
Using the tilt shift lens, the composition for this photo is great because it has me in focus but blurs the edges to create a great focus point.
Like the previous photo, the tilt shift lens blurs the edges to focus on Coco instead of the car.
The point of focus is on the picnic tables because the tilt shift lens blurred the left and right edges and focused on the sidewalk.
The composition is set up so the edges are really out of focus and the focus is on the tree. It works for this image because if the left side was in focus, that light would be more distracting.
There are two types of fish-eye lenses – circular and full-frame. Circular fish-eye takes a full 180-degree hemisphere and project this within the frame so that the resulting images is a sphere with a black surround. Full-frame fish-eye lenses are effectively an enlargement of this sphere so that the image fills the frame.
The background of this image is slightly out of focus to draw your eye to the cross. This composition works because I wanted your eye to be focused on the cross and entrance to the church and to not pay much attention to the background.
“There are no bad pictures; that's just how your face looks sometimes.”
The depth of field in this photograph is short which means there was a wide aperture opening with only a small portion of this photo in sharp focus.
This photo has a small depth of field with a large aperture which made the background of this image blurry and out of focus and kept the pole in a sharp focus.
Using a standard lens, I captured the rays of light from the sun in front of Coco's face and, using the rule of thirds, the sun is positioned at the top left intersection. I like having everything in focus and having a deep depth of field.
Using the rule of thirds, the hand is positioned as the point of focus. Everything is in focus so it has a deep depth of field.