Sigma 18mm f/2.8 Filtermatic
Sigma 18mm f/2.8 Filtermatic is a manual focus wide angle lens for full frame cameras.
Has 5 aperture blades, this number of blades are commonly used. Having rounded blades provides out of focus circle shape closer to a circle. Bright lens thanks to the high aperture value
77 mm lens filter diameter, commonly filter size, you have plenty of possibilities this lens deserves a good quality filter. 65 mm long, requires consideration if you want to carry in the camera bag. Weights 350 grams so plan ahead, carry only if really necessary.