4.5mm F2.8 EX DC HSM Circular Fisheye
Pentax K
Sigma 4.5mm F2.8 EX DC HSM Circular Fisheye

About

This is a full frame Pentax K mount lens introduced by Sigma 17 years ago. Its focal length is 5mm with an aperture of ƒ/2.8. You can find a review of it on DPReview.

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KEH is American and has slightly higher grading standards, while MPB is originally from the UK. Both are global leaders in used lens trading.