Mar 12, 2013· It may happen that from 1/1000s to 1/2s you may not obtain apertures which you can set on the CL's lens. In that case you can change the intensity of your lightsource. E.g. at 1/1000 use your slide projector, at 1/2s use a 25W lamp at an appropriate distance to light the screen. Just take care that the screen is lit well-balanced.