film speed

Mar 28, 2018 Written by Lubna Tafzeel Film speed


            Cinematography course Assignment no:1-Date:28th March 2018

Importance of FILM SPEED

  1. Film speed is the measure of a photographic film's sensitivity to light and is a method of correct exposure determination specified in terms of film’s ISO speed and DIN or the rate at which the film passes through a motion picture camera in frames per second.
  2. Film speed measurement-

3.  Film Speed Determination:-

Film speed is found from a plot of optical density vs. log of exposure for the film. There typically are five regions in the curve: the base + fog, the toe, the linear region, the shoulder, and the overexposed region. Determining speed for colour negatives is more complex because it involves separate curves for blue, green, and red.

4. Applying film speed:-

It is used in the exposure equations Four variables are available to obtain the desired effect: Lighting, F-number, film speed and shutter speed.

5. Film speed can also be referred to as ISO because it is defined by how quickly the image can be recorded with a given amount of light. Therefore, a high ISO number is called “Fast”, while a low ISO is referred to as “Slow”.

6. The lower the speed, the longer an exposure to light is necessary to produce image density. If the film speed is higher, it requires less exposure but generally has reduced quality in the form of grain and noise 

7. Slow-speed films generally refer to film with 100-200 ISO ratings. Since the film takes longer to absorb light, it captures detail more effectively

8. Medium speed is 400 ISO. The medium speed is probably the best for general-purpose use and can handle indoor lighting conditions, overcast days and any combination of the two. Even so, it's not suited for action shots or very bright days. 

9. Fast-speed film is usually rated at 800 ISO and above. It's best for moving subjects you might see at a sporting event or concert, using a zoom lens or are shooting in a dimly lit area. On enlarging the photos, they'll likely turn out grainy.

10. Film speed you choose will have a direct effect on the quality and density regardless of whether you're shooting digital or on film. Each film speed is used for different scenarios and lighting conditions.