The HD bayonet mount lens is an improved lens, it has a new bayonet mount, it is optimal for 28mm native lenses, it does not have native vignetting when the dome kit is installed as does the 100-28AD. When the dome kit is installed on the current WAL100-28AD there is a 96% crop required to eliminate dark corners, this is covered in the Inon lens catalog which is on-line as a PDF. Again, the new WAL100-HD will not require cropping when the dome is installed as does the WAL100-28AD. This should result in a full 165 degree FOV for the HD lens with dome vs 157 degrees for the dome equipped 100-28AD and as well it is said it will have less corner distortion with the dome.
The other supposed benefit is that Inon is sharing the specifications for the new bayonet mount so it can be industry shared, whether it is or not remains to be seen.
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