add a close-up filter or macro adapter onto the front of your existing lens
generally this will give you the worst quality but it may be your only option with cameras with fixed lenses or those on a limited budget.
with the main lens focussed at infinity, adding a close up lens will allow closer focus depending on its diopter value:
1 diopter ⇒ 1m
2 diopter ⇒ 0.5m
4 diopter ⇒ 0.25m
When the main lens is focused at its closest normal focus point these distances are somewhat reduced. Maximum magnification depends upon the focal length of the lens in use.
these simple lenses introduce some astigmatism and distortion that is directly proportional to their power, it's best to stop the lens aperture down by 2-3 stops (say from f/2.8 to f/8) when shooting with close-up lenses, especially those with higher diopter numbers.
Rules for stacking close-up lenses: Place the highest-power lens closest to the camera lens, then the next highest, etc. and avoid stacking more than two close-up lenses if possible.
A minor downside is that your camera won't focus to infinity with a close-up lens in place.
LMScope high quality macro/micro adapter fits onto almost any lens of focal length 20-90mm via a step down adapter to its 37mm thread:
LM DSLR 80mm macro:
LM DSLR 40mm macro:
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