On 03.6.8 1:55 AM, "Alan Chan" <[EMAIL PROTECTED]> wrote: > That's what happened when you are sleepy. You said something you shouldn't > have said. Now we know Takeshita didn't make the number up himself. :-)
>> If you made that number up, then you are very good. 7075-T6 is the most >> widely used alloy in the military aircraft industry. I did not quite make up the number but was approximating it. I knew it was a 7000 series and close enough but was not sure if it was bang on. Turned out it was. Sometime, memory serves right ;-). Cheers, Ken P.S. Aircraft grade aluminum is used everywhere. Looking at tightly fitted retainer rings etc of a lens, some stiff materials must be used. But as long as it is aluminum, alloy or not (no pure aluminum please), it is an inherently soft material, used mainly to reduce the weight at the sacrifice of the hardness and the rigidity. Looking at just the back of one my lenses, it does look like light material (and sounds light too when tapped---like my brain :-).
