[Leica] ZM 50/2 planar ?

[freakscene at weirdness.com (Marty Deveney)]

I've been conducting some tests on the Zeiss 50/2, a couple of six-element 
Summicrons of varying vintages and a Konica Hexanon-M 50/2 over the last few 
months (the tests are ongoing).  These lenses are mostly the same basic 
symmetrical six-element double Gauss design, as is the Zuiko 50/1.8 for the 
Olympus OM SLR cameras (I threw a few of these in for comparison).  The 
first six-element Summicron (Type II) is the exception; it differs slightly 
and is a six elements in five groups design.

In good conditions all the RF lenses perform equally.  All are very well 
corrected for spherical abberration (the Zuiko less than the others), which 
means that the issue of optimisation for contrast or resolution is not an 
issue - the designers can optimise for both.  Nonetheless, the designers of 
each of these lenses have made some choices - the Konica appears to have 
slightly more spherical abberration and is slightly lower contrast but 
equivalent in resolution.  Handheld monochrome images from the Zeiss and 
Summicrons using 400 speed film were indistinguishable.  These lenses all 
have slightly different colour rendition.  If you use colour a lot and are 
very sensitive to colour rendition from lenses you may prefer one lens over 
the others; in digital capture it's easy to fix and doesn't matter.  If I'd 
shot a target, I don't doubt I'd have got the same results as Erwin Puts, 
who found that the Zeiss was slightly better in most respects than the 
latest Summicron.

The Zeiss is really outstanding in contrasty light, on back-lit subjects and 
with oblique light that may fall on the front element; the Summicrons are 
very flare-prone in this latter circumstance and the Hexanon moderately so.  
The Summicrons I tested and also the one I used to own also flared a lot 
when taking a picture directly into a bright light.  The Zeiss is very 
flare-resistant.  At least part of this is due to the Zeiss T* coatings; 
they are standard-setting.  The Zuikos I tested (3) are also flare prone, 
but I think this can be put down to poorer collimation, cheaper glass types, 
single-coated internal surfaces and other measures that were taken to make 
this a budget lens.  Olympus were never very good at coating - hough they 
seem to have improved immensely recently.  It is also easier to tell when a 
lens on an SLR is going to flare - you can see it.  The Zuiko is still a 
bargain since you can get very nice ones for $US30-50.

I sold a nice latest type Summicron because the flare issue bothered me - I 
just seemed to have the knack of finding conditions where it would flare and 
as a result I lost 2-4 pictures per roll.  I replaced it with a Hexanon 
because one turned up at the right time at the right price and I like the 
look it gives very much.  If I hadn't found the Hexanon I'd have bought a 
Zeiss.  If you have a modern Summicron you are happy with, you're unlikely 
to gain much by buying the Zeiss.  If you are plagued by flare, you main 
gain something by getting a Zeiss.  I know you have a Nocti, a DR and a 
pre-asph Summilux Steve (have you been spending time with Jeffrey?) - so if 
you're looking for a modern 50 to complement those the Zeiss is probably the 
best.  If you already have a six-element Summicron and you like it, there's 
not much to gain.

The Summilux ASPH is another question altogether . . . these f2 lenses are 
still better performers inside 1.5m and the Summilux ASPH still has visible 
aberrations.  I have always figured that if you can see them, it doesn't 
matter how well corrected they are, you'll still know they are there.  But 
if you had to choose just one 50 mm lens . . . 

Marty


Gallery:
http://gallery.leica-users.org/main.php?g2_itemId=7617

Most people can only judge of things by the experiences of ordinary life, 
but phenomena outside the scope of this are really quite numerous.
        Shen Kuo - 'Dream Pool Essays'


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