| I'm always window shopping on ebay, looking for | | | | focal lengths longer than 50mm. Portrait lenses fall |
| some great deals on lenses. If I had unlimited | | | | in this category. Somewhere around a 90mm lens |
| funds I'd tell you what lenses I'd like to have; they | | | | is good for a ¾ portrait, where a 180mm |
| are written on a board over my desk. I've | | | | is nice for a head and shoulders portrait. If you |
| researched what I need for the kind of | | | | want to get not so close but still personal with |
| photography I do, but I find most people don't | | | | wildlife you should start with something like a |
| know what to look for when looking for a lens | | | | 300mm and go for a 600mm if you really want |
| for their camera. What do all the numbers and | | | | to stay incognito to the grizzly grazing on the side |
| letters mean on the description of the lens? | | | | of the hill. Quality telephotos are very expensive |
| The advantage of having a DSLR is the ability of | | | | because there is a lot of big glass in them and |
| using different lenses specific to the different | | | | they are as long as your arm. |
| types of photography that one does. Living where | | | | So what do all the letters and numbers mean on |
| we do there is little chance we'd ever really get | | | | a lens? In catalogs the focal length is mentioned |
| to see the latest lens that has come out. We | | | | first with the maximum aperture next along with |
| have to read reviews of people who have tested | | | | the filter size in parentheses. So you have 50/1.8 |
| out what we're interested in. Still, it is important to | | | | (52), meaning it is a 50mm (normal) prime lens |
| have some basic knowledge of lenses in order to | | | | with a f1.8 maximum aperture and a 52mm filter |
| be an informed consumer. | | | | size. If it was 28-200/3.8-5.6 macro (62), it would |
| Lenses can be either a single focal length (prime) | | | | mean that the lens was a zoom that's focal length |
| lens or a zoom lens which has a range of many | | | | was wide angle to telephoto with a maximum |
| focal lengths. Prime lenses tend to be of better | | | | aperture of f3.8 @28mm and f5.6 when zoomed |
| quality than zoom lenses because there are | | | | out to 200mm and the screw in filter size would |
| compromises when designing lenses with many | | | | be 62mm. It is also designed for close focusing |
| different focal lengths as opposed to designing a | | | | making it a macro. One thing you will notice is that |
| lens with a single focal length. It is difficult to | | | | when the maximum aperture number is smaller |
| maintain sharpness throughout the lenses full | | | | the price of the lens goes up. A 50mm 1.8 might |
| zoom range. Usually image quality degrades in | | | | be $100, a 50mm 1.4 lens jumps to $300 and a |
| zooms as they are extended to the longer focal | | | | 50mm 1.2 is well over $500. The reason for this is |
| lengths. Recent computer designing of zoom | | | | that in order to get more light through the lens |
| lenses has improved their quality. Though zoom | | | | the glass needs to be bigger and the design more |
| lenses are very popular I gravitate to my favorite | | | | complex. If you often need to photograph at f1.2 |
| prime lens when I want to be assured of a sharp | | | | with your 50mm lens because of low light or you |
| image. It is important to note that most lenses | | | | like the narrow depth of field then it's worth the |
| are sharpest in the middle of their aperture range. | | | | money. On the other hand if you very seldom |
| The exception to this are lenses with large | | | | open up to the maximum aperture you are |
| maximum apertures ( f1.4, 1.2, or 1). This is | | | | wasting your money. As with most tools, those |
| because these lenses are designed to be used at | | | | that are designed for one specific task are better |
| these maximum apertures. I think it is important | | | | than those that are made to do many tasks. |
| for beginners to use a prime lens because it | | | | Many lenses have macro (close focusing) features |
| forces them to think more about how to use just | | | | but there are lenses specially made for close-up |
| one view to compose their photographs. | | | | work and their quality is better. The longer the |
| Lenses are also classified as wide angle, normal | | | | focal length of a macro lens the greater working |
| and telephoto. You can have wide angle, | | | | distance there is from what is being |
| telephoto, or midrange zooms too. How they are | | | | photographed. Perspective control (PC or shift) |
| classified has to do with the film or sensor size. | | | | lenses offer the ability to compensate for lens |
| What is considered a normal lens for a 35mm | | | | distortion when photographing buildings. |
| camera is a telephoto to a camera with a smaller | | | | Architectural photographers use these. There are |
| APS (DX) size sensor or a wide angle to a larger | | | | portrait lenses that are soft focus or offer |
| medium format camera. Since there are many | | | | defocus control for those who desire softness or |
| different sensor formats (sizes) many times focal | | | | nice bokeh to their images. Mirror telephotos offer |
| lengths are talked about as 35mm equivalents, | | | | an inexpensive alternative to expensive long |
| (what the focal length would be for a 35mm | | | | lenses. They are much shorter and lighter because |
| camera). Lenses are measured in focal lengths by | | | | they have less glass and a mirror in their design. |
| millimeters. A normal lens is one where the angle | | | | Quality is marginal and they have a fixed aperture |
| of view is close to what we normally see with | | | | which is usually slow meaning you can't use them |
| our eyes (50mm). A wide angle lens is one that | | | | in low light. The lens' bokeh will also be rendered |
| encompasses a wider angle of view than we | | | | with circles because of the mirror. |
| normally observe (50mm). | | | | Some other acronyms on lens descriptions are: IF, |
| All lenses are made to gather and focus light onto | | | | internal focusing (the lens doesn't rotate and |
| a specific point. They also have an iris that | | | | extend while focusing), AF, auto focus, VR or IS, |
| controls the amount of light allowed to pass | | | | vibration reduction or image stabilization feature |
| through the lens. The iris is made up of thin blades | | | | built into the lens so it is possible to hand hold |
| that are put together and adjust to form | | | | your camera using slower shutter speeds. LD, ED |
| different sized openings. The iris in our eyes is | | | | or APO glass, low dispersion, extra low dispersion |
| round but the iris in the lens is really a polygon | | | | glass or apochromatic glass (lens elements that |
| because it is made of hard edged blades. The | | | | are designed to focus the different wavelengths |
| more blades that make up the lenses iris the | | | | of colored light onto the same plane). You might |
| smoother the circle of the iris will be and the | | | | also see mention of aspherical lens elements. |
| smoother the out-of-focus areas will appear. This | | | | Lenses are typically sections of a sphere. Lenses |
| out-of-focus smoothness is called the lenses | | | | must focus light onto the flat plane of film or a |
| bokeh (bow-kuh). Higher quality lenses will have | | | | digital sensor while our eyes must focus onto the |
| more blades in their irises. | | | | back of our eye, which is also spherical. In order |
| So what different kinds of lenses are there? | | | | for light to be focused on to the flat plane of film |
| Talking in 35mm camera equivalents here, wide | | | | or a digital sensor lens elements are made |
| angle lenses are those with focal lengths under | | | | aspherical to compensate for the diffraction of |
| 50mm. A 28mm lens is a moderate wide angle | | | | light through the lens. |
| whereas a 14mm is a fish eye with an extreme | | | | Many top of the line lenses have very quiet |
| angle of view. With a fish eye lens you have to | | | | motors that run the auto focus. You may see |
| make sure your feet aren't in the photograph | | | | USM (ultrasonic motor) on Canon lenses and other |
| when shooting. Telephoto lenses are ones with | | | | mentions of quiet focusing on other brands. |