What is film iso 400?

Film ISO 400 is a film speed that falls in the middle range of available film speeds. The ISO number represents the sensitivity of the film to light, with higher numbers indicating greater sensitivity. Films with an ISO of 400 are considered fast films that are able to capture images in low light conditions or fast-moving subjects. This makes them a popular choice for indoor or outdoor photography, photojournalism, and street photography. Additionally, film ISO 400 usually provides a good balance between grain and sharpness, making it an excellent all-purpose choice for many photographers. However, higher ISO films will result in faster shutter speeds and smaller apertures which will give you less depth of field and may require additional light source or longer exposure time depending on the lighting.