Close-up and Macro Photography for Entomologists

Variable Close-up Lenses

Variable close-up lenses screw into the filter mount on front of a normal lens, in the same way as ordinary close-up lenses. However, by turning a ring the power can be changed, and different magnifications achieved. Definition is not as good as that provided by a macro lens or by simple close-up lenses, but at small apertures the results may be adequate for some purposes. Try one out on your camera before buying. There is a slight light loss, but not enough to need compensation.

Variable close-up lens with 50 mm lens on 35 mm camera

Camera focus	Attachment focus	Working distance	Subject size	Magnification
infinity	furthest	490 mm	390 × 260 mm	0.09
infinity	closest	95 mm	126 × 84 mm	0.29
closest	furthest	160 mm	141 × 94 mm	0.26
closest	closest	41 mm	72 × 48 mm	0.5

Range of magnifications with 50 mm lens on 35 mm camera

Magnification
0	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1.0

Good points

Much cheaper than a macro lens.
Fun to play with.

Bad points

Definition is not as good as with normal close-up lenses.
Design prevents use of ring-flash.
Bulk makes lighting difficult at closest distance.