Re: [Leica] CDI tests: was Consensus? Skopar 24mm

[Lucien <director@ubi.edu>]

The German Foto Magazin (February 2000) was giving 9,8/10 to
the Skopar 25/4 and 9,4/10 to the M 21/2,8 ASPH. for the
optical quality.
And for the mechanical quality it's 9,6/10 for the Skopar
and 9,4/10 for the ASPH.

Are those test serious is the question !

Lucien


Mikiro wrote:
> 
> At 5:50 AM +0200 00.4.7, Dominique.Pellissier@droit-eco.univ-nancy2.fr
> >Tests made by Chasseur d'images : n。 219/dec.99.
> >
> >The bargraph is graduated from "weak" to "excellent".
> >I've chosen the following rating : "weak" =1; "poor"=2;"good"=3;"very
> >good"=4;"excellent"=5.
> >The first grade is for the center of the lens ; the second for the edge.
> >
> >Cosina 15 :
> >at 4.5 :1.5;1
> >at 8 :3;3 (="good,good"). The optimum.
> >
> >My comment : not too bad for a 15.
> >
> >By comparison, for the elmar R 3.5/15 (in fact a Zeiss Distagon): 3;2 at
> >full aperture and 4;3 at the optimum (5.6 and 8).
> >
> >Cosina 24 :
> >
> >at 4 : 1.5;1.5
> >at 8 : 3.5 ; 3. The optimum.
> >
> >By comparison the elmarit M 24 gives :
> >
> >at 4 : 4;4 (=very good, very good)
> >at 8 : 5,4 the optimum.
> >
> >My comment : no need for a photo finish!
> >
> >Dominique
> 
> Dominique,
> 
> I am also a regular reader of this CdI.  I should tell you that their test
> results are sometimes very different from what I have felt with my own
> lenses.  I am not familiar with how they do MTF tests and rate the results,
> but let me point out two things.
> 
> 1) MTF tests someties give false results because they are easily affected by
> measurement conditions.  Asahi Camera also does MTF tests in their review
> articles.  When they have results very different from those pubslished by
> the manufacturers, they will do tests again with the manufacturers.  In some
> cases, a re-test gives better results that are nearer to what manufacturers
> officially publish.
> 
> 2) Some variation in production is unavoidable.  Asahi Camera sometimes
> tries a second sample.  The source of the samples is also important.  Some
> journals have their test material from manufacturers, which should be one of
> their best.
> 
> I love looking at MTF charts as well as taking pictures.  However, I do not
> rely on one single test.  BTW, if I remember correctly, Aashi Camera
> reported very good MTF results with these Cosina lenses.
> 
> Amicalement,
> 
> Mikiro

Mikiro wrote:
> 
> At 5:50 AM +0200 00.4.7, Dominique.Pellissier@droit-eco.univ-nancy2.fr
> >Tests made by Chasseur d'images : n。 219/dec.99.
> >
> >The bargraph is graduated from "weak" to "excellent".
> >I've chosen the following rating : "weak" =1; "poor"=2;"good"=3;"very
> >good"=4;"excellent"=5.
> >The first grade is for the center of the lens ; the second for the edge.
> >
> >Cosina 15 :
> >at 4.5 :1.5;1
> >at 8 :3;3 (="good,good"). The optimum.
> >
> >My comment : not too bad for a 15.
> >
> >By comparison, for the elmar R 3.5/15 (in fact a Zeiss Distagon): 3;2 at
> >full aperture and 4;3 at the optimum (5.6 and 8).
> >
> >Cosina 24 :
> >
> >at 4 : 1.5;1.5
> >at 8 : 3.5 ; 3. The optimum.
> >
> >By comparison the elmarit M 24 gives :
> >
> >at 4 : 4;4 (=very good, very good)
> >at 8 : 5,4 the optimum.
> >
> >My comment : no need for a photo finish!
> >
> >Dominique
> 
> Dominique,
> 
> I am also a regular reader of this CdI.  I should tell you that their test
> results are sometimes very different from what I have felt with my own
> lenses.  I am not familiar with how they do MTF tests and rate the results,
> but let me point out two things.
> 
> 1) MTF tests someties give false results because they are easily affected by
> measurement conditions.  Asahi Camera also does MTF tests in their review
> articles.  When they have results very different from those pubslished by
> the manufacturers, they will do tests again with the manufacturers.  In some
> cases, a re-test gives better results that are nearer to what manufacturers
> officially publish.
> 
> 2) Some variation in production is unavoidable.  Asahi Camera sometimes
> tries a second sample.  The source of the samples is also important.  Some
> journals have their test material from manufacturers, which should be one of
> their best.
> 
> I love looking at MTF charts as well as taking pictures.  However, I do not
> rely on one single test.  BTW, if I remember correctly, Aashi Camera
> reported very good MTF results with these Cosina lenses.
> 
> Amicalement,
> 
> Mikiro