We sometimes encounter cameras shutters that allow us to set the camera exposure in terms of exposure value (Ev), a quantity that reflects the joint effect on exposure of shutter speed and aperture. An example is the Prontor SVS shutter often found on Graflex Century Graphic cameras with the Graflar 101 mm lens.

I have just posted to my technical information site, the Pumpkin, a new tutorial article, "Setting Camera Exposure in Terms of Ev", available here:

http://doug.kerr.home.att.net/pumpkin/index.htm#SettingEv

This brief (!) article explains what Ev means (and doesn't) and the significance and use of the Ev scale on camera shutters.

Ev is a part of an overall system called APEX, The Additive System of Photographic Exposure. An extensive discussion of this entire system is given in my companion article, "APEX - The Additive System of Photographic Exposure", available here:

http://doug.kerr.home.att.net/pumpkin/index.htm#APEX