Botanical Photography-5 
Botanical Photography-5
Camera Lenses |
| Most Cameral
Lenses are identified by their focal lengths. A typical lens is 50 mm. Telephoto lenses range from 100 - 500 mm. Wide angle lenses range from 35 mm - 8 mm. The latter is called a fish-eye lens because it produces enormous spherical distortions. It is possible to buy variable zoom lenses which can have a wide range of focal lengths. These can be ideal for field work but are beyond my realm of experience. |
| A "Macrolens"
is capable of close-up photography. Most macrolenses have a 50 mm focal length. My macro lens allows me to make a 1:2 photo. This means that when it is fully extended, the subject will be 1/2 its actual size on the film. Thus a 1 cm-long object would measure 5 mm on the film. A 1:1 macro lens would produce a life-size image on the film. Thus, my 1 cm friend would be 1 cm long on my film. |
You
can make your normal lens into a macrolens in three ways. A] Use Diopter Filters. [A & B] are good for field work. [C] is good for work with a copy stand to which your camera is fastened. |
| Diopter
filters screw onto the front of the lens like other filters. They come in sets of +1, +2 & +4 OR solo (+5). A +5 diopter makes my 1:2 macrolens a 1:1 macro! These are great because they fit in your pocket and are easy to put on and off. Furthermore, they do not diminish the amount of light that hits the film. The individual filters can be combined. The set of 3 combined
= +7. They can produce spherical aberrations. This means that the peripheral areas of the photo may be blurry. This is solved by the flash!!!!!! |
