Pretty sure that looks like Pentax mount
Sigma AF Super Wide II 24mm F2.8 Lens Reviews - Sigma Lenses - Pentax Lens Review Database
Sigma AF Super Wide II 24mm F2.8 reviews and specifications. Auto focus successor to the Superwide II (several reviews of this lens were posted [url=https://www.. This is a Sigma Prime lens.www.pentaxforums.com
Yes relative positions of all the features (red dot, locking hole, contacts, aperture readout, AF screw & stop down lever) are identical. more specifically it's a PKA autofocus variant (probably KA2).Pretty sure that looks like Pentax mount
Sigma AF Super Wide II 24mm F2.8 Lens Reviews - Sigma Lenses - Pentax Lens Review Database
Sigma AF Super Wide II 24mm F2.8 reviews and specifications. Auto focus successor to the Superwide II (several reviews of this lens were posted [url=https://www.. This is a Sigma Prime lens.www.pentaxforums.com
Yes relative positions of all the features (red dot, locking hole, contacts, aperture readout, AF screw & stop down lever) are identical. more specifically it's a PKA autofocus variant (probably KA2).
FWIW OM mount is easily recognised by the two buttons either side of the rear of the lens (lens release & DOF preview). M42 is slightly trickier as there is a T2 thread with the same 42mm OD but a finer pitch. Some adapter rings even label T2 threads as M42 (technically they are M42x0.75 while Pentax screw is M42x1)