Since much of our discussion of the past few days was lost in the switch back & forth between the two servers. I thought I'd post an update on my thoughts on "build quality."
So often I read that an experienced photographer can evaluate build quality just by the "feel" of the camera and by how "solid" it is. While some of that has to do with evaluating operational issues, such as how easy it is to turn the shutter speed dial while you're looking through the viewfinder, much of it has simply to do with the weight of the camera. Leica continues to make their M-cameras from brass just as they did 50 years ago when this was probably the best metal for the job. However, they don't make all their cameras of brass, so there must be good reasons to look at other alternatives.
Brass is a soft metal, so it must be used in heavier amounts to achieve the same strength as some other more modern metals. Titanium was used for the Contax G & is well known for its excellent strength-to-weight ratio although it is expensive. Carl Zeiss AG & Cosina chose magnesium for the Zeiss Ikon, so I decided to do some research on magnesium since the weight difference between the ZI & the M7 is almost entirely due to the selection of magnesium instead of brass.
Magnesium is the lightest structural metal available, but its combination of low density & good mechanical strength results in a high strength-to-weight ratio. Magnesium alloys can absorb energy elastically, making them resistant to shock. They also have good dent resistance & high damping capacity. Modern alloys have added other elements for additional strength & have eliminated pure magnesium's problem of lack of resistance to corrosion. Such alloys have also made magnesium the easiest of the structural alloys to machine, resulting in significant cost savings in the manufacturing process. Some of its common usages today are for wrist watch bodies, housings in power tools, and parts in automobiles such as valve & timing covers, brackets, clutch-transfer housings, & windshield-wiper motor housings.
I'm convinced that the prejudice toward heavier metals as an indicator of a more solid build is erroneous & in the case of brass vs magnesium adds unnecessary cost. The issue of weight depends on the usage for which the camera is intended & is not necessarily good or bad. When thinking of real world problems with build quality, they typically have nothing to do with the "heft" of the camera. Some examples that come to mind are the repeated misalignment problems with the hefty Konica Hexar RF & some CV Bessa models, problems with dust in the viewfinder of the M7 due to faulty seals, the notorious disappearing focus patch on the M6 due to uncontrolled flare, and the problems of loose front elements on some recent Leica lenses due to the use of glue instead of screws to secure these elements. I hope that Zeiss has addressed these issues with their quality control program & with tests for vibration & shock in their "torture chamber" (environmental testing lab). I see no way of evaluating these issues by inspecting a camera - unless parts are falling off - so I will look for reports from users when they get to handle them & put them through their paces in the next few weeks.
Cheers,
Huck