0.2 m (7.9 in)
f/2.8 - f/22
| Ultra-Wide-Angle, Prime Lens|
The Canon EF 15mm f/2.8 was a fisheye lens produced by Canon from 1987 to 2011. The lens was compatible with all EF camera bodies but only intended for full-frame configurations, as the fisheye effect is much less pronounced with a cropped sensor (APS-C).
In 2010 Canon announced the upcoming EF 8–15mm f/4L Fisheye USM which replaced the EF 15mm f/2.8.
Canon EF 15mm lens Wikipedia
The EF 15mm is a full-frame fisheye lens, not a circular fisheye lens.
This means that it provides a full 180° angle of view only across the diagonal; it does not provide a complete hemispherical view, and is not suitable for hemispherical photography.