there are a bunch of possible ways to go for macro already listed with each and every ones personal favourite, so maybe the OP needs a summary.
basically there are 2 equipment approaches for macro / close up photography.
- Add a close up lens to the front of the camera, what this does is change (reduce) the focal length of the combined lens and as the distance to the sensor plane has not changed you can now focus closer at the loss of infinity focus
- Add an extension behind the lens such that it reduces the focusing distance,
both methods rely on the basic principle that magnification ultimately is the ratio between the subject to lens and sensor to lens distance.
adding to the front of the lens includes using close up lenses, marked in diopters, or by taking an existing lens and reversing it and attaching it to the front of another lens,
increasing the space on the back side of a lens is achieved either by adding a bellows, or extension tubes, a focusing helix, or is exactly what older style macro lenses actually did, provide a huge focusing helix and allow the lens to extend far away from the camera reducing allowing for both high magnification and close working distances.
there are pros and cons for both approaches the problem with close up lenses, is that as they effectively reduce the focal length of you lens, to achieve 1:1 magnification you may find your working distance is very short, but since they reduce the overall focal length, and the lens diameter has not changed, you actually gain in F stops, and as a result you have more light, and a bright viewfinder
lens extensions, effectively allow the light gathered by the lens to be spread out further, and as a result, you lose F stops, and the image gets dimmer, but you have greater subject working distance.
remember that for 1:1 the subject to lens and lens to camera distances are equal and exactly 2x the focal length, so lets consider a practical example, you have a 50mm lens, for 1:1 you need 50 mm of extension tubes and you have 100 mm distance from the lens element to the subject (roughly) for close up lenses to work up to 1:1 you would need to add to a 50mm lens you would need to add 11 diopters (most close up lens kits are a 1,2,4 diopter set so you would stack all 3 but that wont get you 1:1 reproduction with a 50mm but you will get a bright viewfinder.
it is a trade off, this is why for real micro work people use a short (i.e. wide angle lens) reversed
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