From: fiddler@concertina.Eng.Sun.COM (steve hix)
Newsgroups: rec.photo
Subject: Re: polycarbonate camera bodies
Date: 12 Aug 1992 22:19:06 GMT
Organization: Sun Microsystems, Mt. View, Ca.
NNTP-Posting-Host: concertina

In article <1992Aug12.164443.29081@midway.uchicago.edu> ar12@midway.uchicago.edu writes:
>the use of composite materials which may be rated at greater strength per
>unit weight than a given metal are also typically vastly less dense-so
>to actually take advantage of that greater strength per unit weight, you'd
>need a camera body greatly increased in size to accomodate the necessary
>increase in volume of material needed to exceed the per unit weight strength
>of a given metal. 

The places where plastics can replace metal in camera bodies are typically
places where the metal in question is a thin sheet.  The (mostly plastic)
back of my T90 is stiffer in torsion than the steel backs of a lot of older
cameras I've played with in the past.

Let the engineers get on with what they're doing.  The have a pretty good
handle on what the requirements of the job are.  (If they're wrong, they'll
find out where it counts most: their pocket books and in the marketplace.)

>Furthermore, in the case of camera bodies, we're not
>talking about carbon-fiber, we're talking about plastic. 

Quite a few of the structural plastics in use are fiber-reinforced materials.
Most of this is probably glass-fibre, but some is carbon-fibre reinforced,
too.

>Finally, someone
>also suggested that this whole discussion is moot since key structural &
>mounting components are metal- not so- ie: Canon. 

Depends on which model Canon you're talking about.  I know of one EOS model
that uses a plastic lens mount...the EOS-1 certainly doesn't do this.

Obviously, the (low-end) model with the plastic mount is not expected to be
attached to any of their large, heavy, expensive lenses.  For the expected
usage, it probably makes good sense.  (And gives Canon a way to field test
non-metal mounts fairly safely.)  Looks weird, though.

>Even the Nikon 8008
>is a hybrid (a little platic here, a little metal there)- and recently
>people on this net have complained about bending/breaking lens mounts
>on this beloved plastic wonder (I have one and hate it, by the way).

I know people who have broken lens mounts on Nikon F's, F2's, FM2's,
Canon F-1's, FTb's, Leicaflexes, Hasselblads, and others.  Hefty metal
machines, all (or almost all).  It's not common, but you can overstress
anything if you try hard enough.

>Well, just my $.02 worth. Again, my complaint is with the manufacturers who
>have sacrified quality while increasing profitability- to make this
>worse are the sales critters spewing the "plastic is better" line...

For most customers, "plastic is better" really *is* true.  For some, it
isn't.

Don't forget that you *don't have to buy* a plastic-bodied camera if you
don't want to!  There are still alternatives available, even if it's
getting harder to find *new* all-metal gear. (Sigh.)  The days of predominently
all-metal construction are gone.  Money is certainly a consideration in
their (relative) demise, but it's not the *only* consideration.

Maybe you'd be happier, btw, with a *real* camera; one that uses fine
hardwoods and leather.  :}

Me?  I think I'll pick up another F-1 while they're still fairly
plentiful...

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