Inon UWL-100 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 ≥ 35mm (or perhaps a little shorter), but the system tended to vignette with cameras having minimum f = 28mm.  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 bases. 
     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 UWL100 28AD Inon UWL-100 28AD
concave Magnification: ×0.63
Configuration: 4 elements, 4 groups, optical glass with AR coating.
cov Max FOV: 100° UW, 179° in air.
Dimensions /mm: 97.4 Ø, 43.2 L.  Weight: 370g air, 190g UW.
dot_bu Depth rating: 60m.

Camera lens: 24mm f/5.6

uwl100ad_24 uwl100ad_24dt

Radial correction

uwl100ad_24cor uwl100ad_24cdt


Radial correction

Collected correction coefficients - UWL-100 28AD with S100 camera (equiv f = 24mm)

Lens system magnif
FOV Geometry Aberration
a b c a+b+c Δdred Δdblue
Camera + flat port   60.0° 0 0.04 0 0.04 -0.0014 0.0056
Camera 1 84.1° 0 -0.015 0 -0.015 0.0012 0.0012
Port (f = 24mm)     0 0.055 0 0.055 -0.0026 0.0044
UWL-100 28AD 0.63    0.02 -0.1 0 -0.08 -0.0015 0.004

The UWL-100 28AD vignettes with the S100 af f = 24mm, 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. 25mm) 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 camera. 

David W Knight
Pictures by Steve Knight
© Cameras Underwater Ltd. 2102