 Anthony K. Macharia |
Macro Photography Accessories Hi every one and happy new year. Feels good to join you again. My question is about macro photo accessories. I am getting a bit lost in the jargon e.g. close-up lens, 2x magnification ring, macro lens, extension tube, etc. What do I really need? Thank you for your answers.
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Jon Close |
The close-up lens screws onto the front of the lens like a filter. It allows you to get a larger image on film by allowing you to focus at a closer distance than the lens alone is capable. They come in different powers (measured in diopters +1, +2, etc), I don't know how that relates to the resulting image size. Canon's close up lenses models are 250 and 500, which refer instead to how much closer they allow you to focus (250 = .25 m, 500 = .5 m). A close-up lens does not affect the aperture, but you will lose infinity focus. 2 element achromatic models are preferred over those with just a single element. A 1.4x or 2x teleconverter (aka extender, multiplier,) magnifies the image by increasing the focal length while leaving the minimum close focus and infinity focus of the lens unchanged. Because the focal lenth is increased but the nominal aperture diameter is the same, using a 1.4x teleconverter makes the effective aperture 1 stop smaller (f/4 becomes f/5.6), a 2x loses 2 stops (f/4 becomes f/8). An extension tube fits between the lens and the camera body. It has no optical elements, but allows closer focusing giving higher magnification. Common extension tube lengths are 12mm and 25mm, or 12mm, 20mm, and 36mm. They can be stacked for even greater extension. Using extension tubes also changes the effective aperture of the lens. At http://www.thkphoto.com/catalog/k/tubeset.html there is a chart showing the magnification and additional f/stops added (exposure factor) when using different length extension tubes with a 50mm lens.
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