Sensei Rob wrote:

Mako2011 wrote:

Polycarbonate can withstand forces nearly 200 times stronger than steel. 2DPA-1 and Hemp Plastics are also much stronger than steel

This is a bit of a weird one. You'll often hear things like "spider silk is stronger than steel", or in this case, various plastics are stronger than steel, but the figures never really hold up.

For example, if you look at the young's modulus (the point at which a material elastically deforms), you get these figures:

I don't think your numbers tell the practical story

Polycarbonate can withstand blasts of over 900 psi and is about 200 times stronger than steel by weight, and is also more flexible than steel. Polycarbonate typically has a tensile strength of between 55–75 MPa (advantage steel) but has an advantage over metal in strength-to-stiffness Ratio. Many PC have an impact rating in the IK10 range...same as stainless steel.

We also see the use of Polycarbonate with stainless steel fiber. Pros and cons to that one.

Bottom line...the advantages of "plastics" in lens design really do exceed the use of metal by large margin now.  Same basic durability for much less cost and weight with additional design advantages/flexibility

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)