Spot light meter
The spot exposure meter (engl .: spot = point ; Spot Exposure Meter = engl .: spot meter ) is a device from the photographic technique . It is a special exposure meter that enables the photographer to aim at the subject through a viewfinder and to determine the light value of a very narrowly defined area. Spot exposure meters work on the principle of object measurement .
functionality
Spot exposure meters often have a selectable measuring angle from 1 ° to 5 ° or even 10 °. Apart from the necessary viewfinder, they correspond to the normal light meter in the rest of the handling. There are also special attachments for professional hand-held exposure meters that turn them into full-fledged spot exposure meters.
The spot exposure metering is also integrated in some higher quality single lens reflex cameras . With many cameras, the so-called spot measuring field is located in the center of the image and is usually identified by a mark on the focusing screen. The size of the field is approximately one to five percent of the size of the entire imaging area.
With some camera models (e.g. from Nikon ), the area around the active autofocus measuring field can be used for spot metering , not just the center of the image. It is thus possible to measure exposure and distance simultaneously at the same point in the image. This can be an advantage for action-packed subjects and high contrast. In concert photography , for example, it is possible to match exposure and distance to a person's face as they move across the stage without having to pan the camera.
application
Compared to integral or matrix measurement , spot measurement offers significantly better control over the result with little additional effort and a little experience. Spot metering always requires the photographer to decide which part of the subject is important for correct exposure before taking the picture. “Aiming and firing” often leads to incorrect exposures if the small measuring field happens to cover a particularly dark or particularly bright area of the subject.
Light meters are set up for a reflectivity of around 18 percent, which corresponds to a medium gray (see gray card ). Exposure compensation is usually required when measuring exposure on areas of skin. The palms of the hands are - largely independent of the skin color - about one f-stop lighter than a gray card and can serve as a guide.
With spot metering with a measuring field in the center of the image, you first aim at a detail of medium brightness (see above), which is in the same light as the main subject, then adjust the camera manually or save the measured value in the case of automatic cameras, align accordingly the camera to the desired section and then pulls the trigger. This procedure sounds complicated, but after getting used to it, it isn't.
With spot metering on any autofocus metering field , an AF metering field is manually selected that is focused on a detail that is important to the image (a face, for example, with exposure compensation, see above). At this point, exposure and distance are measured simultaneously and triggered without panning the camera. It is important to select a suitable measuring field, since the image section and structure depend on this when using this procedure. With this method it is possible to react more quickly to dynamic subjects (concert photography, sports). However, depending on the appropriate image detail, exposure compensation may need to be set before taking the picture.
Spot exposure metering is also a method of calculating the subject contrast and the resulting mean values. This method according to the zone system was described in detail and propagated by the famous landscape photographer Ansel Adams (1902-1984). Some modern cameras with matrix or multi-field metering are based on these methods when evaluating the lighting conditions, but naturally cannot automatically handle every arbitrary or imaginable subject correctly.
Products
The Spot Meter from Minolta was from the NASA in the moon landing used. Another well-known manufacturer is the German company Gossen , and spot knives from Pentax and Sekonic are also common.