Archived posting to the Leica Users Group, 1997/11/22[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
At 05:36 PM 22-11-97 +0100, you wrote: >I downloaded the two pictures from Dan (and deleted them immediatelely >after the analysis) and noted two things. >In Photoshop I superimposed both pictures and noted that the distance from >the corner of the wooden bench to the white house in the backfround ws >different. So both pictures are taken from a different angle and >perspective, [snip] My >first impression (given the zonal diffenence and the very unsharp >background) than the apertures are not the same. >Erwin The possibiltiy that both lenses were not set at the same apertures has already occured to me, except that I was very careful at the time to make certain that all lenses in the test were set to f2.8, and 1/125 (not 1/60 as I previously reported). I also took pictures at f5.6 and 1/30 sec, but in almost all cases there was some blur visible under the loupe, so I decided not to print those, and yes, I double checked to make certain that I did not inadvertantly print one of the f5.6 negs ;-). Also, the two leica images have identical densities, and the two prints were almost identical in terms of density. Is it possible that 2.8 on one lens is not the same as 2.8 on another? Also, it is true that I did not stand in exactly the same place for each photo, but I was probably within a one or two foot radius of a common point for all the photos. As I said before, the pictures were originally taken to be part of a "challenge", but that it was flawed. In any case, I agree that this one piece of anecdotal evidence does not prove anything, but I hope to repeat the test under more comtrolled cirmumstances (inanimate subject, tripod, constant light, transparency as well as negative film and several examples at various apertures). Thanks for the analysis, Irwin, I am keeping an open mind in all this! Dan C.