28AD test pictures
Inon introduced the AD bayonet as an ergonomic
(¼-turn attachment) alternative to the screw
thread. Early lenses were designed for f ≥ 35
mm (or perhaps a little shorter), but the system tended to vignette
with cameras having minimum f = 28 mm. This led to
introduction of the 28AD bayonet, which reduced the distance between
the converter back element and housing port. The 28AD mount
base (i.e., port adapter) can be fitted with an extension tube,
allowing AD lenses to be used, and 28AD lenses can be used in AD mount
The Inon UWL-100 28AD is tested below
with the Canon S100 camera (minimum f = 24mm) and a Recsea housing with
a Recsea 28AD port adapter. For results obtained from the camera and
housing without a wide converter, see Canon S100 test pictures
||Inon UWL-100 28AD
Configuration: 4 elements, 4 groups,
optical glass with AR coating.
100° UW, 179° in air.
97.4 Ø, 43.2 L.
Weight: 370 g air, 190 g UW.
rating: 60 m.
Camera lens: 24mm f/5.6
Collected correction coefficients - UWL-100 28AD with
(equiv f = 24mm)
|Camera + flat port
(f = 24mm)
The UWL-100 28AD vignettes with the S100 af f = 24 mm, but this is
pushed out of the final picture after radial correction. In
terms of aberration, the adapter offers a small improvement over the
bare port; but shows noticeable blue-yellow fringing, which is due to
the fairly large distance (ca. 25 mm) between the port and the camera
lens entrance pupil. Cameras with less extreme zoom range
will give better results because the port can be placed closer to the
Pictures by Steve Knight
© David W Knight, Stephen D Knight. 2012, 2018