[Leica] Leica response to Tri Ermar (28/35/50) is retrofocus?

[Paul Roark]

I might add that I find the lens a reasonable one-lens outfit for casual
walk-around, daylight photography.  However, I do not consider it up to
Leica prime standards, aside from maybe the 35mm f/8 performance.  The zoom
sits at home usually.  The relatively new 28 f/2 and 75 f/2.5 are the main
optics that will accompany me to Europe this spring.  (The 135mm will be in
its separate case for occasional use.)  For Sony, the primes take the
KolariVision UT cover glass modification to perform well.

Paul
www.PaulRoark.com

On Wed, Feb 19, 2020 at 1:21 PM Paul Roark <roark.paul at gmail.com> wrote:

> This is a review that includes a cut-away of the MATE optics here:
>
>
> https://www.stevehuffphoto.com/2010/11/11/the-leica-mate-lens-review-medium-angle-tri-elmar-by-ashwin-rao/
>
>
> Paul
> www.PaulRoark.com
>
> On Wed, Feb 19, 2020 at 12:43 PM Ken Iisaka <ken at iisaka.com> wrote:
>
>> I think there is more to it.
>>
>> Tri-Elmar 28-50 is basically a zoom lens with two groups: a positive
>> focusing lens group closer to the film, and a negative group up front. The
>> distance between them is what determines the effective focal length of the
>> lens.
>>
>> To have a negative group up front and having a positive group in the back
>> is the definition of a retrofocus design.
>>
>> At 28mm, the centre of the lens is well ahead of the focal plane,
>> certainly
>> further than 28mm. This indicates that it is effectively a retro focus
>> lens. At 50mm, it is less so.
>>
>> On Wed, 19 Feb 2020 at 11:21, Frank Filippone via LUG <
>> lug at leica-users.org>
>> wrote:
>>
>> >  It is not considered a retrofocus design.
>> >
>> > That's it folks.... Final answer
>> >
>> > Frank Filippone
>> > BMWRed735i at gmail.com
>> >
>> > _______________________________________________
>> > Leica Users Group.
>> > See http://leica-users.org/mailman/listinfo/lug for more information
>> >
>>
>>
>> --
>> Ken Iisaka
>> first name at last name dot org or com
>>
>> _______________________________________________
>> Leica Users Group.
>> See http://leica-users.org/mailman/listinfo/lug for more information
>>
>