From: utzoo!decvax!ucbvax!CAD:tektronix!tekmdp!markp Newsgroups: net.physics Title: slit in spectrograph Article-I.D.: tekmdp.1722 Posted: Thu Jan 27 13:03:16 1983 Received: Sun Jan 30 08:52:21 1983 I'm no expert, but I thought that the function of the slit was to give a "line" of light which is imaged by the grating to form the "lines" of a line-spectrum. Of course the narrower the slit the closer the lines of your spectrum can be without overlapping, but I'll bet that this is true only down to a certain slit narrowness beyond which the diffraction effect of the slit itself causes problems. Always ready to speculate, Mark R. Paulin ...decvax!teklabs!tekmdp!markp