RE: [Leica] Apo-Summicron-M 90/2.0 ASPH tested by CDI

[Paul Chefurka <Paul_Chefurka@pmc-sierra.com>]

Dominique,

Do you have similar MTF numbers for the old 90/2.0?  From my reading of
Leica's MTF chart for the APO, the number of 52% you quote is for 40 lp/mm
at a diameter of 18mm .  At the center the percentage is a a full 10 points
higher.  According to Erwin (as I understand his comments), the 40 lp/mm
reading isn't all that significant in general photography anyway - the 20
lp/mm measurement is of more benefit in predicting the kind of performance
most photographers will see, especially hand-held.

I'm not sure what you mean when you say "this lens is not an absolute
winner".  Against what competition are you measuring it?  Are there other
90/2.0 lenses out there that are better?  Comparing it to the 180/2.8 hardly
seems reasonable - they are very different lenses.  Are you saying that
Leica didn't make it better enough than the old Summicron?

Your comments are confusing - I've got one of these lenses, I've owned the
90 Elmarit-M, and the Summicron is significantly better than that lens at
2.8, as far as I can tell.  It goes without saying that it's infinitely
better than the Elmarit at f/2, which is why I bought it.

Paul Chefurka

> -----Original Message-----
> From: dominique pellissier [mailto:noct@club-internet.fr]
> Sent: Sunday, February 13, 2000 2:56 PM
> To: leica-users@mejac.palo-alto.ca.us
> Subject: Re: [Leica] Apo-Summicron-M 90/2.0 ASPH tested by CDI
> 
> 
> 
> ----- Original Message -----
> From: Dan Cardish <dcardish@microtec.net>
> To: <leica-users@mejac.palo-alto.ca.us>
> Sent: Sunday, February 13, 2000 5:33 PM
> Subject: Re: [Leica] Apo-Summicron-M 90/2.0 ASPH tested by CDI
> 
> 
> > Are you looking at the same MTF charts that I downloaded 
> from the Leica
> > site?  The APO 90 MTF at f2 looks excellent, at least the 
> way I interpret
> it.
> >
> > Dan C.
> >
> > At 05:03 PM 13-02-00 +0100, dominique pellissier wrote:
> > >>
> > >################
> > >On the official Leica site, there are some MTF tests.
> > >If you see the test of the apo90, there is no doubt : at 
> full aperture,
> this
> > >lens is not an absolute winner.
> > >
> > >Conclusion : don't buy the apo90 if you have the old90.
> > >
> ###########
> Yes.
> At full aperture, the contrast  is 52 %. At 5.6 : 72 %. Great 
> difference.
> By comparison (yes, i know, it's not very rigorous to compare 
> lenses of
> different focal lengths) the 2.8/180 apo gives 82 % at full 
> aperture and 82
> % at 5.6.
> Now, let's see the CDI tests for these 2 lenses.
> For the apo90 : good (center), good (edges) at full aperture 
> and excellent,
> very good at 5.6.
> For the apo 2.8/180 : very good, very good at full aperture; 
> same results at
> 5.6.
> The 2 tests are corroborated.
> 
> Leica writes : " The overall performance measures up to the 
> legendary LEICA
> APO-MACRO-ELMARIT-R f/2.8/100 mm from the LEICA R system."
> It's true. But not at full aperture for the 90.
> 
> I keep my elmarit 90...
> 
> 
> 
> 
>