f = 12mm F 2.8 For 2/3 type Cameras C‐Mount Model No. M1228-MPW3 Effective Front φ18.8mm Focal Length 12mm Lens Aperture Rear φ10.3mm Max. Aperture Ratio 1:2.8 2/3 type(Y=5.5mm) -0.10% Max. Image Format 8.8mm x 6.6mm(φ11mm) 1/1.8 type(Y=4.5mm) 0.04% Operation Range Iris F2.8 ‐ 16.0 1/2.5 type(Y=3.55mm) 0.00%