1/1.7-inch type Lenses

Premium compact cameras and later small-sensor interchangeable-lens compacts | 7.44 x 5.58 mm sensor with a 9.3 mm diagonal

The 1/1.7-inch type format sits above the smallest compact-camera sensors while remaining far below Four Thirds, APS-C, or full-frame. Like other inch-type names, the label is historical rather than literal; the active image area used here is 7.44 x 5.58 mm. It appeared in advanced compacts and some small interchangeable-lens bodies as a way to gain a little more sensor area without giving up pocket-sized lens packages. In the Pentax Q line, it also helps distinguish later larger-sensor bodies from the original 1/2.3-inch type models.

For lens designers, the format keeps the compact-camera advantages of short focal lengths and small image circles, but it gives slightly more room for image quality than 1/2.3-inch type systems. Wide-to-telephoto zoom ratios can still be packaged efficiently, and depth of field remains naturally deep at equivalent fields of view. In the catalog, this format is useful for separating genuinely tiny compact-camera optics from the larger 1-inch and Four Thirds classes, especially when the same small mount family spans more than one sensor size.