Ways to Get Close to the Subject |
Close-up filters (Diopters)
Close-up filters thread onto the end of your existing lenses allowing them to focus closer. They come in varying powers
that are measured in Diopters (just like reading glasses and they work the same way).
Advantages
1) Close-up lenses are the cheapest way to dabble in macro.
2) No exposure compensation is needed (very little light loss).
Disadvantages
1) When the Diopter is in place the lens loses infinity focus.
2) Getting the magnification you want often involves swapping filters.
3) Loss of image quality (especially with cheap Diopters).
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Close focusing and Macro-Lenses
Some lenses can focus close enough to give decent magnifications.
Advantages
1) No loss of infinity focus.
2) Best image quality since these lenses are specially designed for close-up (flat field work).
Disadvantages
1) The most expensive way to do macro.
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Extension tubes and tele-converters
Extension tubes and teleconverters fit between your lens and camera body. Extension tubes are just empty, hollow tubes
while tele-converters have a lens inside. You can calculate the magnification a given tube will allow you to achieve using
a given lens. The formula is the focal length of the lens divided by the length of the tube (with the lens focussed at
infinity). This means tou would need almost 50mm of extension tubes to make a 50mm lens magnify at life size (allowing for
a bit of the lens built in extension).
Advantages
1) Teleconvertors can also be used to extend telephoto lenses and thus utility beyond just macro-work.
2) Tubes do not degrade the image quality.
Disadvantages
1) Teleconverters degrade image quality.
2) The lens loses infinity focus with a tube attached.
3) Extension tubes are not cheap.
4) It is often necessary to swap tube combinations to get the composition you want which can be time consuming.
5) Both teleconverters and tubes cause light loss making composition more difficult, especially with slower lenses.
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Reversing rings
Reversing rings attach to the camera body and allow the lens to be threaded on backwards. They allow you to turn your
lens around and mount it directly to the camera body.
Advantages
1) These rings are quite cheap.
2) You can use your existing lenses.
Disadvantages
1) You lose the ability to do open aperture metering meaning that you must manually stop down the lens when you want to take the photo.
2) You get very little working distance.
3) The magnifications you can achieve this way are limited.
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Macro-Coupling rings
Macro coupling rings have male threads on both sides. They allow you to turn your lens around and screw it onto the end
of another lens, just like a close-up lens (albeit quite powerful). Very high magnifications can be achieved this way. The
formula for magnification is the the focal length of the main lens divided by the focal length of the reversed lens (with
both lenses focussed at infinity). For example, reversing a 50mm lens onto a 100mm lens would give 2x magnification.
Reversing that same 50mm lens onto a 135mm lens would give 2.7x magnification.
Advantages
1) Easiest way to achieve very high magnifications.
2) You can still do open aperture composition.
3) These rings are quite cheap, you can even make your own fairly easily.
Disadvantages
1) Extreme light loss and often severe vignetting results.
2) Working distances can be quite small.
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