Multipliers or Telephoto Extenders with Macro Photography
This is the least favorable macro set up, I think. There are some image problems with older extenders, certain brand extenders can only be used with certain brand lenses, only certain apertures can be used sometimes, and the good ones are expensive. They significantly reduce exposure by a 1 or 2 f stops. With Macro Photography, the battle is always for more light because a smaller aperture is used to increase the Depth of Field, but with a shutter speed fast enough to stop camera shake or movements the subject makes. Multipliers can double magnification if an extension is used between the multiplier and lens.
Make sure the extension tube is between the multiplier and the lens. Using an extension tube between the tube and lens allows my 1.4x multiplier to work with my 100mm macro lens. Without the extension tube the multiplier wouldn’t match since the multiplier sticks out too much.
A 1.4X or 2X teleconverter will increase magnification by about 25-35%. As with an extension tube, less light will reach the film or sensor, and a longer exposure time will be needed. However, working distance remains the same as without the teleconverter. So telephoto extenders offer more magnification and still have the same working distance! Try and stick with the same brand extender as your lens.
A 1.4X extension will reduce light by 1 f stop, and a 2.0 extension will reduce light by 2 f stops. Everything is magnified, the subject, the imperfections of the lens, and camera shake. Using a flash makes the extenders more practical.