The Sigma 4.5mm has an average review score of 75%

Score (%):
Sigma 4.5mm f/2.8 EX DC Circular Fisheye HSM
Multiple user reviews on slrgear.com
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90

Sigma 4.5mm EX DC Fisheye
A fisheye lens is an extreme wide-angle which doesn’t attempt to correct distortion and produces a characteristically ‘rounded’ look, where nearby objects appear hugely distorted and things in the background shrink to tiny specks. Fisheye lenses come in two types: full-frame and circular. The 4.5mm lens we’re looking at this time produces a circular image which falls entirely inside the sensor’s imaging area, so that you end up with a circular image in a rectangula...
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60