anyone out there ever use a barrel lens on a Crown, using a lens cap to control exposure?? I can't envision any particular problems doing it, just looking for others experiences
thanks,

other than fast or consistent exposures it's not a problem at all. A variation of the lens cap shutter is called the country shutter. It's nothing more than half a 4x5 film box (black interior) on a paint stick. The paint stick is about a foot long, which gives you leverage--a small movement of your hand equals a large movement of the box. So you can open and close the lens with a flick of the wrist, rather than your arm. With a little practice you can get speeds as fast as 1/15th of a second--Good enough for shooting portraits under the trees at f4.5 with ISO 100 or 200 film on a bright day.

You can also try using the dark slide. By holding it horizontally by the upper corner, you pivot the slide out and back in the path of the lens in a quick wrist flick. This method is best used when the camera, operator and the darkslide are in shadow, as the dark slide is reflective and could cause flare on the lens if the sun is behind you.

The country shutter is also useful when you want more than one pop of the flash, but don't want ambient light build up while the flash is recharging. The country shutter lessens the chance of moving the camera while re-cocking the shutter.