Why plastic is trash for cameras

Discussion in 'Digital SLR' started by Rich, Aug 24, 2005.

  1. Rich

    Rich Guest

    Just another example. This fellow dropped a lens.
    It broke at the plastic point, even though the lens was
    a plastic-metal combo. Polycarbonate versus aluminum, stainless
    or magnesium? No contest.
    -Rich

    http://www.pbase.com/ckraft/image/48137019
     
    Rich, Aug 24, 2005
    #1
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  2. Rich

    Charlie Self Guest

    No one explained to "this fellow" that dropping lenses was not a great
    idea, regardless of material?
     
    Charlie Self, Aug 24, 2005
    #2
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  3. So, I knew this guy, and he had a plastic thing, and it broke, and he's
    all like "Plastic is crap, man" and I was "no way" and he goes "Way" but
    that's because he's a lamer.
     
    Brion K. Lienhart, Aug 24, 2005
    #3
  4. Rich

    Zeke Galama Guest

    On the other hand - an old-fashon lens is much heavier, and the shock is
    stronger when dropped. Besides, the plastic lens is normally prized at the
    same level as repairing the other lens.

    Only one conclusion: Don't drop lenses, and if you do - blaim yourself and
    not the material.
     
    Zeke Galama, Aug 24, 2005
    #4
  5. Rich

    Pete D Guest

    So you have done comparison tests with an all metal lens to show that the
    same will not happen? No, I thought not, I guess that makes you a troll
    then!
     
    Pete D, Aug 24, 2005
    #5
  6. Rich

    Rich Guest

    Then pray Canon makes "L" lenses in plastic.
    Not likely.
     
    Rich, Aug 24, 2005
    #6
  7. Rich

    Brian Baird Guest

    Or that the plastic used in this lens was most likely NOT polycarbonate?

    He's a dense fellow, for sure.
     
    Brian Baird, Aug 24, 2005
    #7
  8. Rich

    Rich Guest

    Apparently, the plastic wasn't!
     
    Rich, Aug 25, 2005
    #8
  9. Rich

    Brian Baird Guest

    So Rich, or "Michael", whatever your name is:

    Why don't you pipe down? You like making really bold statements for
    attention, yet you do a very poor job of it. Frankly, you're boring.
    You bore me.
     
    Brian Baird, Aug 25, 2005
    #9
  10. Rich

    Charles Guest


    that's right, but this fellow (me, in this case) would probably have
    guessed that dropping lenses was not a good idea if he had been asked
    about it, even without someone explaining it to me.

    Having the cheap lens break rather than the more expensive camera
    might not be such a bad idea.
     
    Charles, Aug 25, 2005
    #10
  11. Rich

    Skip M Guest

    Ok, that doesn't show a weakness in plastic, it shows a weakness in the
    joint. The same thing could happen with a steel/aluminum connection, too.
    Notice that the plastic isn't broken, just the junction. So the lesson here
    is to buy a lens of a homogeneous construction, all plastic, all metal,
    whatever...
     
    Skip M, Aug 25, 2005
    #11
  12. Rich

    RichA Guest

    Ever see where they have to put a screw into plastic? On anything
    with quality, it will have a brass or other metal insert. Why?
    Because plastic can't hold threads. Ever notice that if a piece
    of plastic has a screw hole in an area near the edge, it's very easy
    to fracture from the screw hole outward? Metal is superior in both
    cases.
    -Rich


    "Bittorrents are REFUNDS for all the BAD movie products Hollywood
    never gave us refunds for in the past"
     
    RichA, Aug 26, 2005
    #12
  13. Rich

    no one Guest

    Happens sometimes though.
     
    no one, Aug 26, 2005
    #13
  14. Rich

    Charles Guest


    In this case the plastic did break, and there were no metal inserts
    where the screws went into the plastic. there were 4 screws holding
    the rear portion of the lens to the main body, two screws pulled out,
    the other tow came with plastic attached.

    for sure, metal would have been stronger, something like stainless
    steel would have prevented the lens from breaking at this point. Hard
    to guess what other damage might have happened.

    It was an inexpensive lens, made inexpensivly.
     
    Charles, Aug 26, 2005
    #14
  15. Rich

    RichA Guest

    As I've pointed out before, plastic is a cost-saver, nothing more.
    Even weight doesn't enter into it because for most lenses, the weight
    comes from the glass, not thin-walled aluminum castings.
    -Rich


    "Bittorrents are REFUNDS for all the BAD movie products Hollywood
    never gave us refunds for in the past"
     
    RichA, Aug 26, 2005
    #15
  16. So now you're an expert materials engineer? Is there anything you can't
    do? All hail Emperor Rich!
     
    Brion K. Lienhart, Aug 26, 2005
    #16
  17. Gisle Hannemyr, Aug 26, 2005
    #17
  18. Rich

    Charlie Self Guest

    Sure. And sometimes thin metal castings break, just about as easily as
    plastic moldings, but no one seems to bother posting those.
    Understrength specifications always fail easily, regardless of
    material. Plastic is not a perfect material for all camera molding
    uses, but it is not as bad, nor is it as cheap, as too many people
    imply. If the moldings are done correctly, using the correct plastic,
    with support for things like screw threads where needed, they'll be as
    durable as something like a thin magnesium or aluminum castings.
     
    Charlie Self, Aug 26, 2005
    #18
  19. Rich

    Brian Baird Guest

    Brian Baird, Aug 26, 2005
    #19
  20. Rich

    eawckyegcy Guest

    eawckyegcy, Aug 27, 2005
    #20
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