The Lens by Michael Leyba

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There are many types of lens on the market for cameras. Lens are most commonly for sale to fit amateur and professional 35mm single lens reflex cameras.

Listed below are the various types of lenses.
Zoom: Changing focal length from wider to more restricted view. The lenses are measured in millimeter. The lower the number the wider the angle of view. 10mm for a 35mm or digital Single Lens Reflex (SLR) camera would be considered wide angle and possibly fisheye for the distortion of curvature around the subject in the middle.
There are normal zoom lens that have focal lengths near the normal angle of view from the viewpoint of the human eye. This is normally about 50-55mm lens.
A zoom telephoto is a lens that allows you to have a wider focal length with a longer focal length. They are great for getting up close to wildlife, close to fast action sports that could be dangerous, and capture the distortion of objects that are separated by distances, yet look up close or close together due to this lens.

Fixed Focal Length: This lens can not change it’s appearance of angle of view. A 50mm normal lens is an example of a fixed focal length lens. To increase the angle of view you actually have to back up or to decrease the angle of view you have to move closer with the camera and lens. Advantages for the fixed focal length lens is that it can be sharper than a zoom lens and also have a wider aperture.

Telephoto: This is a narrow field of view. It allows the user to get closer to the scene to be photographed without getting physically closer.

Wide Angle: This is a wide field of view. It allows the user to move away from the scene to be photographed without getting physically away.

Normal: This is the angle of view that is closest to the human eye. We things without distortion.

Fast: Amount of light the lens lets into the camera. This is usually a very low f-stop or aperture for the lens. For instance, a telephoto with an aperture of f2.8 is faster than the next f-stop up of f4. Very fast lenses are f1.2, f1.4, f1.8, f2, f2.8. It depends too on the focal length of the lens as to how fast it is. For instance a 50mm f2.8 lens would be considered slow versus a 500mm f2.8 would be very fast.

The most common type of lens used today is the zoom lens. There are several types of zoom lens. One type is a wide-angle zoom lens that is useful for taking photographs of interiors or indoor settings. This lens ranges from about 20mm to 80mm. The smaller the number in millimeters the greater the angle is. If we had perfect peripheral vision we could see to the left, right, up, and down perfectly. A wide angle lens generally is not the choice for portraiture.
The middle range zoom lens is well suited for portraits. The focal length on these lenses generally is between 70mm to 150mm. These limit the distortion in portraits, yet do not make exaggerations of a person’s form.

The long range or telephoto range of zoom lens is for getting closer to distant objects like wildlife, sports action, or to narrow the depth of field of a subject. The focal length is usually 150mm-600mm.

Some lenses have the ability to move left and right. These are called shift lens and they work similar to view cameras in their ability to move left and right so part of image will be in focus if it is on the plane of the lens. They are expensive lens and require experience in their use; therefore, not generally for the consumer.

Close-up lens or macro lens allows the photographer to photograph things that are very small or that they want to get large photographs of small details on the object. These lens can sometimes be referred to as filters as they might screw into the end of the lens and magnify what is seen by using diopters or scales of magnification. Some lens have macro features that allow them to be used normally as lens, but allow them also to photograph up close. This is referred to as the minimum focusing distance.

There are two types of lens showing the light coming from the direction of going into in general convex ) is where light would be like a windshield that bounced light off it and concave ( where the light is collected like a satellite dish. The convex lens is thicker in the middle then the edges. The concave lens is thicker on the edges than in the center. The light bends outward or inward depending on the type of lens. These lens are curved glass that due to the curve can have magnifying or the opposite of magnifying of making things seem smaller. There are several of these lenses in a camera lens. The quality of them makes the image clear and distortion free. The amount of distortion around the edge of the lens is a guide to the quality of the lens. All lens have some distortion around the edge of the lens and image created. This is called aberration. Some of the types of aberration are distortion, curvature of field, spherical aberration, chromatic aberration, oblique aberration and coma. Lens use refraction of light as they bend light from the source to the sensor. Our eyes also use refraction to see.

Most camera lenses are made of glass, but some are made of plastic. The quality of the glass or plastic will determine the quality of the lens. One of the first lenses was a pinhole. The tiny hole acted as a lens and due to the small aperture the image projected was in focus. The light must be very intense or the time that the pinhole lets in light very long for an image to result. There is a new lens that has been on the market a few years called,”Lensbaby.” It is a movable lens. It can rock back and forth since it is on a rubber neck. It has certain areas in focus and others that can be distorted.

The lens is the eye to the camera and therefore one of the most important parts of a camera. If the lens is dirty than the image will be dirty. It is the first thing and the last thing to look at for photography quality.

Thanks for listening,

Michael

Michael Leyba
Portrait by Michael
http://www.michaelleyba.com

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