dirk hr spennemann photography

 

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What is 'Banding' ?
 

Widelux F-series

'Banding' is a phenomenon of uneven exposure of a negative as the lens turret travels its 126º arc across the horizontal field of vision. If the movement of the lens turret is smooth and even, then the expousre will also be even (although it may result in some section of the image being overexposed). There are three factors that can cause and influence 'banding'

  1. Wear and tear in the gears and cogwheels, commonly a worn or bent tooth. As a result the turret retarded at regular intervals and does not travel evenly.
  2. Dirt in the gears and cogwheels or the speed regulating cups.
  3. Intrusive matter that may inhibit movement of the gears or speed regulators.

Manifestation of banding

Banding can be extreme as this example:

Massive banding in evidence @ f/11 1/125

Or as light as this:

Stop—Look for Trains

If the camera exhibits banding, it is most recognisable in areas of homogenous colours, such as the sky, road bitumen or water surfaces.

It is important to understand that banding may only manifest itself at specific speeds; i.e. a camera may exhibit banding, say at 1/250th, while no banding is visible at /15th and 1/25th.


Mitigation
To fix the banding problem, the turret should be exercised regularly. In addition, a deep CLA may be required.