[Leica] any Sony rx 1 users

[roark.paul at gmail.com (Paul Roark)]

Mark,

I agree, in general, with what you are saying.  However, assembly
costs of Cosina may be enough less that an equal optic can be made for
less.  Also, Leica can command more for the same just because of the
name.  So, there are differences in both the supply and demand sides
of the equation that may sometimes modify the strict "you get what you
pay for" formula, particularly if we are just looking at optical
performance.

I put a fair amount of weight on the published MTFs of the 2
companies.  While the MTFs of Leica and Zeiss may not be exactly
comparable, the main performance variances I've seen from either --
actually only Zeiss -- appear to be due to de-centering and focus
distance sensitivity.  Specifically, my Zeiss 50mm f/2 has off-axis
performance that takes its f/4 performance way below what the MTF
represented.  It is also clearly de-centered, and that may well
account for the deviation from the published MTF.  I buy from
retailers where I can send things back.  I did send 2 of the samples
back.  After the third de-centered sample I gave up and decided for my
uses and given the budget I had to spend at the time, I'd just accept
an optic that was barely better than the Canon equivalents, and
clearly not assembled with the perfection of the sample they tested
for the published MTF.  (I have a sharp mountain ridge view from my
back yard that easily detects a decentered optic.)

Subsequently, I did purchase a Leica 50 f/1.4 ASPH, and it is the best
1.4 I've used or tested.  However, consistent with it's MTF, I can see
a dip in performance, particularly wide open, half way out from the
center to the edge.  Also, the Zeiss f/2 is sharper in the center at
f8.  So, the Leica is not a perfect optic by any means (and it's way
heavier).  I might add that I've never had/tested a de-centered Leica
lens, and the Leica MTF representations have been right-on all the
time.

The 18 ZM -- my other Zeiss disappointment -- is a retrofocus that is
simply not good in the corners close up.  (My Rollei SL66 50 Distagon
was terrible there also.)   It's a likely eBay item in the future.

On the other hand, the ZM optics I have that are well
assembled/centered, the Biogons, have relative performances -- Leica
v. Zeiss v. MTFs -- that were very much predicted by the MTFs the 2
companies publish.  The 35 f/2.8 Biogon image, in terms of sharpness,
looks very much like that of the 28mm f/2.8 Elmarit ASPH I also have.
On the other hand, the published MTF of the 35mm Summarit 2.5 is very
unimpressive wide open -- sufficiently so that I am not interested.  I
believe Leica here and appreciate their honesty.  I also believe
Leica's MTF for its 35 f/2, and at f/2 it is not good enough to pay
for given my usual landscape shooting.   So, the Zeiss simply seemed
to have the best combination of price and performance for my uses at
this focal length.  Same with the 21mm focal length.

Down the road I may find that the Zeiss optics fall apart, whereas the
Leica ones are far more robust; they do have that feel.  So, far,
however, the Zeiss Biogons I have deliver performances that are right
up with the very good Leica optics but at a lower price, and so far
they have held up fine.

So, I tend to pick the optics based on the MTF as well as price.  I
don't expect magic from either (or any) company.

For those interested, I've posted a Jpeg containing copies of the MTF
charts of the optics I have and others of interest from Leica & Zeiss.
 See http://www.paulroark.com/BW-Info/Leica-Zeiss-MTF.jpg .

Paul
www.PaulRoark.com