Archived posting to the Leica Users Group, 1999/01/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]"Martin V. Howard" <marho@ida.liu.se> wrote: >Guido Ridoli wrote: >> >> Is it possible to measure the brightness and focal lenght of an >> external finder for example, there is a great difference in >> brightness between a 35mm finder SBLOO and a 35 mm WEISU; >> and if it is, can we measure a "kind of f/stop" for an external >> finder? > >Shine a light of known strength through the finder and measure the >strength of the light (lux? lumen? something else?) on the other side. >Would that work for an absolute rating? > >Illuminate the white side of a grey-card (90% reflectance) with >uniform diffuse light. Use a spot meter to measure through the view- >finder to get a reading. Use same spot meter to measure through another >viewfinder. Provide a relative rating. Feasible? This is entirely feasible and is exactly what I did to compare the brightness of my M6 finder with that on my Mamiya 7. I got fed up with people denigrating the Mamiya and saying that the Leica viewfinder was much brighter. I was convinced that there was very little difference and the test proved that to be correct. The M6 viewfinder is indeed brighter than the Mamiya but only by a small fraction of a stop. Simon.