it's nice but mine wasn't calibrated properly in terms of focus, maybe it's made like that
I recall having used several tries at adjusting the focus on Jakovs 16mm f/3.5 - sometimes it would render the scene less sharp than other times,,, especially with Infra Red captures.
The adjustment of the lens elements of the rear cell seems to be very tricky to get right,,,
Fisheye-Hemi can be quite useful for de-fishing or partly de-fishing an image - However care must be taken when shooting, be aware of the huge amount of cropping de-fishing causes,,,
I once used it for a 200 person event capture
But it's lightweight super Wide
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