Advantages:
Large aperture 1.8, no need for flash when shooting in dark places. The large aperture (77mm filter) makes it very cool when shooting outdoors. The image is sharp and the out-of-focus image is smooth. Low price and extremely cost-effective professional head. For commonly used focal lengths, fixed focus heads are preferred.
Disadvantages:
Like other brands of original fixed-focus large-aperture lenses, AF is often inaccurate (commonly known as out-of-focus). Only machines with focus fine-tuning can be purchased with confidence. Machines without focus fine adjustment must be selected on site. Small brands such as Pentax are slightly more expensive than other brands.
Summary:
For experienced photographers, this head is worth having.