Archived posting to the Leica Users Group, 2011/06/23

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Subject: [Leica] New Leica M Stuff
From: henningw at archiphoto.com (Henning Wulff)
Date: Thu, 23 Jun 2011 22:07:47 -0700
References: <78360B7C-76FD-4E7A-A744-C1F95F887902@charter.net> <CA26873F.1095D%mark@rabinergroup.com> <20110622030649.GA63482@selenium.125px.com> <BANLkTikB+aa3cQM49hjJQppmFubQmW29zQ@mail.gmail.com> <20110622042815.GB63482@selenium.125px.com> <BANLkTikcr+t9qgfuxdbD4+nQcdpR9-=Dww@mail.gmail.com> <20110622044205.GC63482@selenium.125px.com> <p06230904ca27419383db@192.168.1.8> <010b01cc30ea$19a891a0$4cf9b4e0$@earthlink.net> <p06230903ca291d250cfc@192.168.1.8> <BANLkTinh3Yvd2iQ+xLFoNL_94k3ToP4d5g@mail.gmail.com>

Thanks, I couldn't find where I'd gotten them again.


>And there's a good explanation of MTF as a starter here:
>http://www.luminous-landscape.com/tutorials/understanding-series/lens-contrast.shtml
>
>The Zeiss brochures Henning mentioned are:
>http://www.zeiss.de/C12567A8003B8B6F/EmbedTitelIntern/CLN_30_MTF_en/$File/CLN_MTF_Kurven_EN.pdf
>and
>http://www.zeiss.de/C12567A8003B8B6F/EmbedTitelIntern/CLN_31_MTF_en/$File/CLN_MTF_Kurven_2_en.pdf
>
>Marty
>
>On Fri, Jun 24, 2011 at 3:10 AM, Henning Wulff 
><henningw at archiphoto.com> wrote:
>>  Hi Frank,
>>
>>  The MTF curves give some indication of the relative performance, but
>>  certainly not all. Zeiss put out a couple of brochures that give a very 
>> good
>>  general explanation of MTF curves. If you want me to send them to you, 
>> send
>>  me a note off-list.
>>
>>  The MTF curves give an indication of the point transfer function of the
>>  lenses, so if the solid lines (for sagittal structures) and dashed lines
>>  (tangential structures) overlap, a point light source will be imaged as a
>>  slightly diffuse circle. If both lines are at 100%, the point will be 
>> imaged
>>  as a point. The lower the contrast value (%), the larger the diffuse 
>> circle;
>>  the more the two lines diverge, the more elongated the now oval diffuse
>>  circle becomes. This leads to flare and 'bleeding'.
>>
>>  All of this only applies at the plane of focus. Little about the out of
>>  focus imaging qualities can be deduced from these graphs. Also, testing
>>  protocols can vary quite a bit and still be 'accurate', so graphs from
>>  different manufacturers, or even different testers from the same
>>  manufacturer can't be compared reasonably.
>>
>>  There's a lot more to optics than these graphs can show, so they always 
>> have
>>  to be taken with a grain (kilo) of salt.
>>
>>  The Summilux at f/1.4 has the weakest performance (surprise, surprise!), 
>> but
>>  by f/2.8 is quite respectable and very close overall to that of the 
>> Elmarit
>>  ASPH. Especially the larger and medium details are rendered very well 
>> across
>>  the field, and if anything are rendered a bit better further out in the
>>  field by the Summilux than the Elmarit. Extremely fine detail has pretty
>>  good resolution but lower contrast than the Elmarit.
>>
>>  All the lenses are very good in the central 15mm at all apertures, with 
>> very
>>  fine detail rendered at high contrast; only the Summilux at the widest
>>  apertures falls off a bit here.
>>
>>  At f/4 there are actually only two categories in performance: the
>>  Super-Elmar and the others. The other three each have their strong points
>>  and their weak points (relatively), but the Super-Elmar is best. The 
>> Super
>>  Elmar has a very slight increase in performance at the edges at f/5.6, 
>> but
>>  for the most actually loses performance as it is stopped down.
>>
>>  So from the graphs the Super-Elmar is definitely the best, but the others
>>  are all outstanding lenses. The Summilux, for example, is a fair bit 
>> better
>>  at f/1.4 than the non-ASPH Elmarit was at f/2.8.
>>
>>  The Tri-Elmar is quite interesting in that at f/4 it's performance is 
>> quite
>>  similar to that of the f/3.4 Super Angulon at f/5.6, except the far 
>> corners
>>  of the T-E are better than those of the SA. The old f/4 SA was noticeably
>>  worse than the f/3.4, and closer to the non-ASPH Elmarit in performance.
>>
>>  At present I have a number of 21's; the Summilux, the Elmarit-ASPH, the
>>  Tri-Elmar, the f/3.4 SA and the CV f/4. The CV is decent, but lacks the
>>  clarity of the Leica lenses and all samples I've tried of the CV have had
>>  some decentering, which I've not had with the Leica lenses. The CV is not
>>  bad, but it's just not as good. The SA isn't useable on the digital M's, 
>> so
>>  it's hard for me to really compare it. On B&W film I still like it, but 
>> it
>>  clearly is not a modern optic. The other three I use pretty much
>>  interchangeably. The Summilux has a bit more distortion than the others, 
>> and
>>  the distortion on the Tri-Elmar is a bit more strongly mustache-shaped, 
>> so
>>  the Elmarit wins here. At medium apertures they are largely equivalent 
>> for
>>  practical purposes, and I tend to carry one or the other depending on 
>> their
>>  other attributes. Since distortion can be corrected in software when
>>  necessary, it's not as big a deal anymore as it was in film days, and the
>>  other qualities are reasonably given priority.
>>
>>
>>
>>
>>
>>
>>  At 7:38 AM -0700 6/22/11, Frank Filippone wrote:
>>>
>>>  Henning... you are among the few LUGgites that can read and make sense 
>>> of
>>>  MTF charts.
>>>
>>>  Can you give a quickie review of the MTF charts for the 4 x 21mm lenses?
>>>   21
>>>  ASPH Elmarit, WATE, Summilux, and Super Elmar.
>>>
>>>  I have always wondered their relative merits....
>>>
>>>
>>>
>>>  Frank Filippone
>>>  Red735i at earthlink.net
>>>
>>>
>>>   From the MTF graphs the new 21 looks as good as anything ever made at
>>>  that
>>>  focal length, but it's not perfect :-). Still has distortion, the 
>>> sagittal
>>>  and tangential curves don't cover each other, they're not all above 95 
>>> at
>>>  40lp/mm, and there is significant light falloff.
>>>  When will they ever make a perfect lens??? :-)
>>>
>>>
>>>
>>>
>>>  _______________________________________________
>>>  Leica Users Group.
>>>  See http://leica-users.org/mailman/listinfo/lug for more information
>>
>>  --
>>
>>       Henning J. Wulff
>>   Wulff Photography & Design
>>  mailto:henningw at archiphoto.com
>>   http://www.archiphoto.com
>>
>>  _______________________________________________
>>  Leica Users Group.
>>  See http://leica-users.org/mailman/listinfo/lug for more information
>>
>
>_______________________________________________
>Leica Users Group.
>See http://leica-users.org/mailman/listinfo/lug for more information

-- 

       Henning J. Wulff
  Wulff Photography & Design
mailto:henningw at archiphoto.com
   http://www.archiphoto.com


In reply to: Message from s.dimitrov at charter.net (Slobodan Dimitrov) ([Leica] New Leica M Stuff)
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Message from tgray at 125px.com (Tim Gray) ([Leica] New Leica M Stuff)
Message from benedenia at gmail.com (Marty Deveney) ([Leica] New Leica M Stuff)
Message from tgray at 125px.com (Tim Gray) ([Leica] New Leica M Stuff)
Message from msadat at gmail.com (mehrdad) ([Leica] New Leica M Stuff)
Message from tgray at 125px.com (Tim Gray) ([Leica] New Leica M Stuff)
Message from red735i at earthlink.net (Frank Filippone) ([Leica] New Leica M Stuff)
Message from benedenia at gmail.com (Marty Deveney) ([Leica] New Leica M Stuff)