[Leica] M4 versus M6

[Erwin Puts <imxputs@knoware.nl>]

Stephen Gandy and now Mike Johnston noted that in their opinion the 
M4 is the last Leica build to standards where cost would be of no 
concern. Mike includes the seven element Summicron to belong to that 
same class. The implication as I see it is that the current Leica 
models are build with a cost conscious mind.
Now what is truth here? And what is the importance of such a 
statement if true? I am not trying to discuss opinions. If anybody 
would say: "I regard the <whatever camera or whatever lens> to be the 
best build ever" I would not even try to comment. Opinions are just 
that: a person's view about whatever.
But as soon as an opinion is transformed into a fact, we need proof.
First we need a testable definition of what constitutes a manufacture 
"where cost is no concern". Secondly we need a standard of deviation 
where any manufacture would depart from that definition.  One of my 
hobbies is the engineering of old trucks and one of my favorites is 
the Mack "Red Ball Express". According to current engineering  the 
strength of the basic chassis could be assessed as overkill and the 
same structural integrity could be secured with a different 
engineering. The second approach might be notified as  "cost cutting" 
as less material is involved. But the new design is smarter and uses 
more mathematics to get the same durability and longevity. So is cost 
cutting in itself a bad act and does it lead by necessity to a lesser 
product? Not at all!
But independently of the consequences and implications of cost 
cutting, we need to establish some criteria to be able to note when a 
design is beyond these criteria. The original 7 element chrome 
Summicron weights 285 grams. The current chrome version of the 
Summicron weights 335 grams. The current one has six elements. Now 
assume for the sake of the argument that the amount of  material of 
the mount has been reduced or that the choice of material is such 
that in the past some part would be brass where it is now a light 
alloy. Is that bad? But the surfaces of the lens elements have a 
coating that is more laborious/expensive to apply and the surfaces 
itself are better, that is more accurately/more expensivlye finished 
and the mounting is more laborious/expensive because more attention 
is given to the process of centring the lens elements. The glass is 
more costly etc. Now how do we establish that the 7-element version 
is built with a perspective of  "cost is of no concern". We should 
dismantle both lenses and look at the material, the precision of 
machining and of mounting and we should know about the process/cost 
of producing/assembling  this lens then and now. Only when we know 
this all and have verified it, a statement can be made. And as we do 
not have so, any statement about cost cutting is at best a 
hypothesis, yet to be proven.
My position here has nothing to do with not accepting any critique 
about any current Leica product. I deplore the dust in current 
lenses, the friction of the distance rings, the rough moving of 
aperture rings, the nonalignment of rangefinder patches, the not 
functioning of electronics, the flare in the viewfinder etc.
I also note that when putting an older Leica lens on the bench I have 
a 50% chance of decentring and when putting a current lens on the 
bench this same chance is less than 5%. That is progress! Is it the 
result of cost cutting?
The same story can be told for the M4/M6 comparison. Nor Mr Gandy nor 
Mr Johnston have disassembled an M4 and an M6 and have proved with 
solid engineering arguments that the M4 is better built or is built 
with a "cost is irrelevant"- perspective, whatever that is supposed 
to be.
In fact we have returned to that enigmatic discussion that "they do 
not built them now as they did in the past". I did disassemble an M3 
and M6 and compared it gear for gear, screw by screw and component by 
component. My conclusion? Read the above.

Erwin