How your film camera’s light meter can be fooled.
Shooting with black & white film in snow using the manual settings of your camera requires some exposure adjustment. A manual camera, or a camera in the “Manual” or “M” setting, means you, the photographer, select the aperture and the shutter speed when taking pictures. The light meter in your camera averages the scene and suggests what setting will give you the best exposure. But, the light meter also “sees” everything in middle gray.
If you are shooting a scene with snow and accept the the exposure reading by the camera’s meter, it may look something like this:
The light meter averaged the scene to gray which made the snow look dingy and the subjects underexposed. This negative would be difficult to print.
The solution to getting a proper exposure is to override the meter’s suggested exposure setting by increasing the amount of light coming through the lens. Basically, you are overexposing the scene to make the snow appear white and to bring out the details in the subjects.
It is recommended by film manufacturers to overexpose snowy scenes (or bright sandy beaches for that matter) by 1 stop. That means increasing (opening) the lens aperature to the next bigger opening. For example, if the camera meter reads the scene at f8, adjust your lens by turning the aperture ring to f5.6. This will double the amount of light passing through the lens.
Remember, the smaller the f stop number the larger the lens opening.
If your lens has smaller increments between full stops, known as 1/3 or 1/2 stops. You can shoot frames between f8 and f5.6. This “bracketing” of your exposures gives you several choices on which negative will yield the best exposure for printing your picture.