Schneider Optics is expanding its 138mm diopter line-up, offering three new strengths of both full and split-field diopters that bring the total range of diopter offerings to seven.

New +1/8, +1/4 and +3/4 strengths are being added to the existing +1/2, +1, +2 and +3 138mm diopter lenses. The full diopters magnify the image on the way into the lens to allow focus on subjects that are closer to the camera than the attached lens could normally handle. The split diopters magnify only half of the image, leaving the other portion unaffected — a good strategy for extending the apparent depth of field of a lens by bringing foreground elements in one part of the frame into focus along with background elements in another part of the frame.

“The split-field diopter lens is particularly effective when you need to bring both foreground and background into sharp focus simultaneously but the primary lens by itself cannot provide sufficient depth-of-field, even with the lens iris closed down fully,” explained Schneider VP of MPTV Filters Ira Tiffen in a prepared statement. “It allows for different treatment of foreground and background simultaneously.”

A split diopter was used to get Kevin Costner’s face in focus in parts of this scene from ​The Untouchables.

Split diopters are often associated with director Brian De Palma, who uses them fairly often and to good effect, but they have long been a staple of adventurous cinematography, especially in the 1970s, and in these days of widescreen LCDs they’re being used in television programming, too. (They’ve even been spotted in Saturday Night Live‘s increasingly cinematic digital shorts; see more examples at VashiVisuals.) Rather than get the shot in camera, you could achieve a similar effect with a digital composite — but where’s the fun in that?

Schneider’s diopters, mounted inside black anodized aluminum rings, have anti-reflective coatings that eliminate the need for exposure compensation, the company said. The 138mm diopters are $475 each in both full and split versions.