Manual Control Options
The S3 UVIR has two control dials, which make manual mode convenient. One handles aperture and the other takes care of shutter speed. That's important because manual exposure is the only way to get useful images with the S3 UVIR. ISO and dynamic range can also be set manually.
Focus
Auto Focus
The S3 UVIR has the S3's autofocus system, but it doesn't work with IR or UV filters mounted on the lens, and it is calibrated to focus visible light. IR and UV light focus slightly differently, and with most lenses, focus should be racked out about half a percent of the focal length for maximum sharpness.
Manual Focus
Manual focus with the live preview is a little tricky. Our best results with it involved mounting the camera on a tripod, framing the image without a filter, getting a rough focus manually through the viewfinder, and then putting the filter on the camera and firing up the live preview. Live preview requires hitting the menu button and pressing a button a second time to bring up the view on the LCD. The LCD view remains visible for 30 seconds and a countdown timer keeps track. The view can be magnified to aid in focus. The 30-second limit is necessary because the sensor heats up. The S3 UVIR apparently keeps track of the heat because it won't allow repeated live views without a cool-down period in between.
Exposure/Metering
The S3 UVIR has the S3's light meter, but it simply doesn't give accurate results. It's not sensitive to UV or IR. User will have to establish exposure through trial and error or by creating standardized setups in a controlled environment.
White Balance
The S3's white balance controls remain on the S3 UVIR, but they don't work. The imaging chip has red, green, and blue sensors, but they are more or less equally sensitive to infrared and ultraviolet light, so their color data are contaminated. We didn't have the opportunity to test the S3 UVIR with a UVIR cutoff filter, which theoretically ought to turn the camera back into an S3. Our understanding is that the cutoff filters don't necessarily match the camera's original cutoff filter perfectly, so color would be close, but not quite like the original camera.
ISO
The S3's ISO control remains intact, allowing settings from 100 to 1600, in full EV steps. ISO simply controls how much the camera amplifies the signal from the sensor, so it works just the same way in IR and UV as in visible light. Noise increases with ISO. For most of our shooting, an ISO of 400 worked out well.
Shutter Speed
The S3 UVIR allows exposures of 1/4000 to 30 seconds, with a maximum flash sync of 1/180. The S3 body offers only 1/2-EV steps, not the more typical 1/3-EV.
Aperture
The S3 UVIR controls the aperture of AF Nikkor lenses via electronic contacts in the lens mount. It can set aperture in 1/2-EV increments.
