Setting the Lens F-Stop
Note:
Lens manufacturers probably do not recommend actually doing this, but we have had no
trouble with it. But if it breaks your lens, remember we said not to really do it.
Most fast lenses will have to be stopped down to give the best performance. Normally when a
lens is removed from the camera body, the aperture automatically reverts to its wide open
position.
To set the f-stop on the lens for use with a CCD camera requires setting it on a DSLR body first.
Attach the lens as normal to the DSLR body and turn the camera on. Make sure the camera is in
“aperture priority” mode, usually by setting the dial on top to “A.” Use the appropriate controls to
set the desired f-stop.
Now, hold down the “depth of field preview” button, located on the camera body near the base of
the lens, usually on the left from the photographer's perspective. While holding this button down,
remove the lens from the camera body. This takes a little dexterity to hold the depth of field
button while also pressing the lens release button and twisting the lens off. The lens will now be
stopped down.
To revert to the fully open position, simply reattach the lens to the DSLR body and power it up.
Now take it off normally and it will be wide open again.
