Called a Waterhouse Stop. A lot of old lenses took them and
nearly all process lenses took them. Not always for very small
stops, for half-tone work the dots are really somewhat defocused
images of the aperature so the shape can be important. Sometimes
square and, for three color, sometimes sort of football shaped at
various angles.
Weston may have done this for extended depth of field but
the resolution is also affected, becoming less at small stops, so
depth and very small aperatures may become counter productive.
Also: I have written before about the method used to measure
film speed and its history. The important part here is that
overexposure, if not extreme, does no damage and may improve tone
rendition. Shooting B&W still film at half the ISO speed is
probably advantageous under many circumstances. Note that the
method for measuring the speed of B&W motion picture film and all
color films is different so this is not applicable to them.
On 2/17/2019 11:44 AM, Richard Lahrson wrote:
Weston's pepper: he had spec. aperture plate, like f/280 or something.Richard Knoppow
On Sun, Feb 17, 2019 at 11:41 AM Richard Lahrson <gtripspud@xxxxxxxxx <mailto:gtripspud@xxxxxxxxx>> wrote:
Well, if it's a studio set up, test.
