تويت
العدسات .. البدء .. كيفية التقاط وتطوير الصور بالأبيض والأسود
LENSES
For all the sophistication of modern camera mechanisms , and the way in which they are heavily promoted , it is the lens that makes the essential difference to the quality and character of the image . As long as the camera , and in particular its shutter , is reliable , there is not much more that you need ask of it , provided that you I have some method of measuring the exposure .
Interchangeable lenses , however , offer a world of varied images . While most cameras are supplied with a standard lens - one that has a focal length that gives a normal perspective - you can choose from a range that includes ' fisheye ' lenses at one end of the scale to long telephotos at the other . For most people , the major distinction between lenses is in their focal length . This determines the angle of view , and this in turn controls the perspective and magnification .
In the 35mm markets , the choice of lenses is particularly wide , not only because each camera manufacturer produces a range ( typically between a dozen and twenty focal lengths ) , but because there are also independent lens makers . Faced with such a choice , it pays to think carefully about the uses to which you could put extra lenses , and how many you are prepared to carry around . Unless you have a very specific subject of interest that demands an unusual type of lens ( such as a long telephoto for wildlife ) , it makes sense to start with a modest selection . Exotic fish - eyes and shift lenses can come later .
For the time being , we are considering equipment that is basic rather than sophisticated , and it is worth looking at what the most popular focal lengths are overall . For most photographers , the first acquisitions beyond the standard lens which is usually 50mm ) are a moderate wide - angle ( around 28 or 35mm ) and a moderate telephoto ( 135 or 150mm ) . There is no rule that says this is a neces- sary selection , but this range of three lenses is a first useful step in broadening the range of photographs that you can make .
ABOVE Equipping yourself with zoom lenses can be cheaper , and in some ways gives greater versatility , than choosing fixed focal length models . Currently very popular , ' standard ' zooms ( top ) usually offer a focal length range from mild wide - angle ( 28mm or 35mm ) to mild telephoto ( 70mm or 85mm ) , and are normally quite compact . Standard zooms are available that offer greater telephoto magnification , while maintaining their wide angle capability ( above ) . These lenses sometimes exploit their telephoto edge by offering a macro facility ( second from top ) , enabling the photographer to take close - up pictures .
Focal Lengths
This diagram displays the range of different angles of view encompassed by the commonly - available 35mm format . At one extreme , there is the 16mm fish - eye , which takes in almost 180 degrees of the scene - though with considerable circular distortion . At the other extreme is the 800mm telephoto , taking in a mere 3 degrees . The standard 50mm lens falls roughly half - way between , taking in about 40 degrees .
LEFT Modern SLRs invariably accept a bewildering array of lenses . Shown here is just a fraction the range available for the autofocus Pentax SFX .
An alternative to a few separate lenses of fixed focal length is one or two zoom lenses . A zoom lens has a number of floating glass elements that can be moved to alter the focal length continuously . The ranges vary , but on a 35- 70mm zoom , for example , any angle between the two limits can be selected . The advantages are obvious - one lens doing the job of several and an almost infinite choice of framing - but there are also two drawbacks . One is the weight and bulk of the lens , always greater than a fixed focal length equivalent , the other is that the maximum aperture is smaller , and so the lens is not quite as fast ' as it could otherwise be made . Whether you choose fixed focal length lenses or zooms is a matter of personal preference .
LENSES
For all the sophistication of modern camera mechanisms , and the way in which they are heavily promoted , it is the lens that makes the essential difference to the quality and character of the image . As long as the camera , and in particular its shutter , is reliable , there is not much more that you need ask of it , provided that you I have some method of measuring the exposure .
Interchangeable lenses , however , offer a world of varied images . While most cameras are supplied with a standard lens - one that has a focal length that gives a normal perspective - you can choose from a range that includes ' fisheye ' lenses at one end of the scale to long telephotos at the other . For most people , the major distinction between lenses is in their focal length . This determines the angle of view , and this in turn controls the perspective and magnification .
In the 35mm markets , the choice of lenses is particularly wide , not only because each camera manufacturer produces a range ( typically between a dozen and twenty focal lengths ) , but because there are also independent lens makers . Faced with such a choice , it pays to think carefully about the uses to which you could put extra lenses , and how many you are prepared to carry around . Unless you have a very specific subject of interest that demands an unusual type of lens ( such as a long telephoto for wildlife ) , it makes sense to start with a modest selection . Exotic fish - eyes and shift lenses can come later .
For the time being , we are considering equipment that is basic rather than sophisticated , and it is worth looking at what the most popular focal lengths are overall . For most photographers , the first acquisitions beyond the standard lens which is usually 50mm ) are a moderate wide - angle ( around 28 or 35mm ) and a moderate telephoto ( 135 or 150mm ) . There is no rule that says this is a neces- sary selection , but this range of three lenses is a first useful step in broadening the range of photographs that you can make .
ABOVE Equipping yourself with zoom lenses can be cheaper , and in some ways gives greater versatility , than choosing fixed focal length models . Currently very popular , ' standard ' zooms ( top ) usually offer a focal length range from mild wide - angle ( 28mm or 35mm ) to mild telephoto ( 70mm or 85mm ) , and are normally quite compact . Standard zooms are available that offer greater telephoto magnification , while maintaining their wide angle capability ( above ) . These lenses sometimes exploit their telephoto edge by offering a macro facility ( second from top ) , enabling the photographer to take close - up pictures .
Focal Lengths
This diagram displays the range of different angles of view encompassed by the commonly - available 35mm format . At one extreme , there is the 16mm fish - eye , which takes in almost 180 degrees of the scene - though with considerable circular distortion . At the other extreme is the 800mm telephoto , taking in a mere 3 degrees . The standard 50mm lens falls roughly half - way between , taking in about 40 degrees .
LEFT Modern SLRs invariably accept a bewildering array of lenses . Shown here is just a fraction the range available for the autofocus Pentax SFX .
An alternative to a few separate lenses of fixed focal length is one or two zoom lenses . A zoom lens has a number of floating glass elements that can be moved to alter the focal length continuously . The ranges vary , but on a 35- 70mm zoom , for example , any angle between the two limits can be selected . The advantages are obvious - one lens doing the job of several and an almost infinite choice of framing - but there are also two drawbacks . One is the weight and bulk of the lens , always greater than a fixed focal length equivalent , the other is that the maximum aperture is smaller , and so the lens is not quite as fast ' as it could otherwise be made . Whether you choose fixed focal length lenses or zooms is a matter of personal preference .
تعليق