There is a common misconception about the direction in which this adjustment needs to be made. In the case of IR the lens must almost invariably be moved somewhat further from the film than visual focus demands. The use of small apertures will in most cases diminish or eliminate the need to make a focus adjustment. When using a fluorescing screen in UV photography the UV rays are properly focused when the image on the screen is sharp. In a sense they change the color of the light falling on them.
Some subjects change short, ultraviolet energy into longer, visible, wavelengths or colors.
Others may change visible rays into yet longer, infrared wavelengths. The former effect is, of course, visible while the latter is not. To photograph fluorescence excited by UV, which usually results in a visible effect, color film can be used to good advantage with Kodachrome 64 being paricularly suitable. For UV work this barrier filter is the 2E or similar, pale yellow, filter. Exposure may possibly be metered in the camera especially with the newer more sensitive in-camera meters.