Supplementary lens that screws onto the front of a prime or zoom lens, reducing the minimum focus distance for extreme macro shots without extension tubes. Essential for production-ready close-ups.
Definition
A diopter (close-up diopter) is an auxiliary lens that screws onto the front of a camera lens to reduce its minimum focusing distance, enabling extreme macro shots. The strength is measured in diopters – the higher the value, the closer the focus. Standard diopters are available in strengths from +1 to +10, with +3 and +5 being the most commonly used.
Unlike macro lenses, a diopter does not alter the focal length of the base lens but acts like a magnifying glass. This allows for close-up shots with any lens without losing the familiar focal length characteristics. The optical quality is largely preserved with high-quality achromatic diopter lenses.
Practical Application
Diopters are primarily used for detail shots – from facial features and product details to symbolic objects. In feature films, they enable intense close-ups of eyes, hands, or important props. In documentaries, they are indispensable for macro shots of nature, technology, or artworks.
The depth of field is drastically reduced by diopters, which can be used for targeted creative blur effects. Precise focusing is important, as even minimal movements can affect sharpness.
Technical Details
The diopter strength determines the new minimum focusing distance: a +2 diopter reduces the minimum distance to approximately 50cm, a +5 diopter to 20cm. Multiple diopters can be combined, but this increases the risk of chromatic aberrations and loss of sharpness at the image edges.