I recently purchased a used Omega SCA-300 color analyzer - but no instructions. I only want to use it for exposure measurements on B&W prints. Can someone help me out with simple instructions on how to use it just for that? The unit has to 2 modes "operate" and "reference." I can set the digital readout while in(the reference mode which seems to be independent of any realtime measurement. Is this setting supposed to be a "guess" of the correct exposure? In the operate mode setting using the attached light detector changes the digital meter readings according to the light and dark part of the photograph. Where should the detector be placed - some mid values I presume? How is the light detector supposed to be oriented since the meter readings varywith position? There is also a control on the remote light detector light slightly rotates the actual light meter on its axis - what's the purpose of that? Any help would be appreciated.