Leica Is The Best Forget The Rest! (2 Viewers)

[Dorian Gray]

I've always suspected that the use of titanium is what explains the tendency of the Ultravid focus to be more sticky than the Ultra/Trinovid focus.

I think the biggest reason for the Ultravid's less-than-buttery focus feel is the fact that it uses grease-free sliding plastic discs rather than lubricated metal gears. Lubricated metal on metal is smoother than just about anything short of ceramics, but the resistance of such a focus mechanism would vary greatly with temperature, due to the variable viscous nature of grease. By eliminating grease Leica have managed to ensure relatively constant focusing resistance across a huge temperature range.

Titanium has many advantageous characteristics in addition to its most appealing property: the highest strength-to-weight ratio of any metal. For example, it is very resistant to corrosion (unlike many steel alloys), it is almost as hard as steel (unlike most aluminium alloys), and it has a very high fatigue limit. This last might be important to Leica. Some metal alloys, such as all aluminium alloys, suffer from a property by which it is impossible to clearly define a strain (stress amplitude) limit, below which the material will not suffer permanent damage. In other words, as aluminium alloys are subjected to daily strain, their life ebbs away, inexorably towards fatigue failure. No matter how stiff the aluminium structure (and aluminium structures tend to be designed to be particularly stiff for this very reason), even small stresses will cause some deformation, and each such cycle causes irreparable harm. By contrast, ferrous alloys and titanium alloys have a clearly defined fatigue limit, which means they can be subjected to an unlimited number of cyclic strains as long as the amplitude falls below a certain value. As long as the designer makes the product stiff enough that all foreseeable strains fall within the fatigue limit of the material, the product will have an indefinite life.

Titanium alloys are also particularly elastic, especially in comparison with other light alloys such as aluminium. So a titanium axle can bend significantly without plastic deformation, returning instead to its exact original shape. Binoculars are dropped from time to time, and if the hinge axle bends permanently they go out of alignment. (If the hinge does not bend yet the binocular still loses alignment due to the failure of another component, the hinge is over-engineered and therefore dead weight: a no-no in today's weight-obsessed climate.) So a titanium axle may reduce the weight by more than appears at first glance and/or increase the durability of the binocular, due to its elastic nature.

I'm not particularly defending the use of titanium in the Ultravids, but Leica do seem to have the kind of corporate philosophy that would allow their designers free reign to make whatever they think is best, almost without regard to cost. In everything they do, from camera lenses to binoculars, Leica is firmly in the land of diminishing returns. The modern Zeiss company on the other hand gives me the impression of designing extremely competent products, but ones designed with a bit of economic sense. Swarovski is obsessed with quality but they probably don't have the R&D clout and materials know-how that Leica have.

By any reasonable assessment Leica should have died a long time ago, but thankfully they still give every sign of kicking despite year after year of dodgy finances!

 

[Alexis Powell]

I think the biggest reason for the Ultravid's less-than-buttery focus feel is the fact that it uses grease-free sliding plastic discs rather than lubricated metal gears.

If you read my post again, you'll see that my comparison is between the focus of a typical Ultravid unit vs a typical Ultra/Trinovid. As far as I know, the focus system of the Ultravid is identical to that of its Ultra/Trinovid BA/BN predecessors but with the substitution of titanium for the central drive shaft. Until the recent incorporation of plastic/teflon washers into the Ultravid focus, I didn't think either model used plastic washers. Neither model uses any grease, but rather rely on "self lubricating" metal parts. In summary, nothing that you've described explain the difference in focusing performance between the average Ultravid and the average Ultra/Trinovid BA/BN. Given the phyical/mechanical reliability of the Trinovid focus, I see no justification for the use of titanium other than marketing (The use of titanium WAS heavily advertised). Leica design is as driven by style as it is mechanical engineering concerns, as can easily be observed from their many products made to be collectibles. Or perhaps I should be made better aware of the unique engineering potential of ostrich hide leather?

--AP

 

[Swissboy]

I think the biggest reason for the Ultravid's less-than-buttery focus feel is the fact that it uses grease-free sliding plastic discs rather than lubricated metal gears. Lubricated metal on metal is smoother than just about anything short of ceramics, but the resistance of such a focus mechanism would vary greatly with temperature, due to the variable viscous nature of grease. By eliminating grease Leica have managed to ensure relatively constant focusing resistance across a huge temperature range....

I had thought this was basically a problem in cold temperatures. But on my recent trip to Australia, I realized that it's a problem for hot conditions as well. My otherwise very fine Zeiss FL 8x42 binoculars just would not stay in the infinity range when I walked around at temperatures in the 30+ Centigrade (Celsius) range. Thus, every time I stopped to look at a bird or something, I had to refocus from scratch. It took a while before I realized what was going on.