I have an ancient and very simple analog light meter which can measure incident and reflected light, but has no spot metering capability. For some reason the protective transparent plastic in front of the small light dome broke. The crack goes across the area covered by the light dome, the dome itself is ok, though.
How likely does this affect my exposure measurements? Can I replace the transparent plastic front with some other piece of plexi glass or are these parts likely made out of some special material?