> -----Original Message----- > From: Chris Brogden [mailto:[EMAIL PROTECTED]] > Sent: 19 November 2002 16:57 > To: [EMAIL PROTECTED] > Subject: RE: SMCP FA 20-35mm f/4 AL or the FA* 24mm f/2 AL > WAS -- Re:WideangleDilemmas > > > On Tue, 19 Nov 2002, Rob Brigham wrote: > > > While I suspect that Brad's comment was pure speculation, I > am certain > > you are wrong that weight is the only advantage to plasics. > I thought > > impact absorbtion was better for one. When plastic is deformed > > slightly it is more likely to return to its original shape > than metal. > > Possibly, but it's also more likely to crack. So many > examples... I've seen so many K-series bodies with dents on > the top plate from being dropped that still worked perfectly. > I bought a Super Program off eBay once that had a cracked > top plate. It didn't dent, just cracked. For digital, I'm > currently using an old Canon S10, which has a metal body. It > used to be my Canon rep's demo camera, and its edges are > covered in many small dents, none of which affect its > performance, only its aesthetics. Now there's no way to say > for sure, but I suspect that some those blows would have been > strong enough to crack a plastic housing, and once you get > the smallest crack the whole integrity of the camera is > threatened, as moisture and dust can get in.
I don't totally disagree, but plastic has come a long way since the super program days. What I am trying to convey is that this is a complex issue and not as simple as saying metal is better for everything than plastic. Certainly when pressed beyond its limits plastic has a tendancy to destroy itself whereas metal just deforms. However, metal deforms much easier and more permanently than plastic under smaller loads and where moving parts are concerned, these dents can cause problems. In a camera casing this is not an issue, so maybe metal is better. I am not saying plastic lenses are better, just that the reverse is not a given. > I'm not a structural or a materials engineer, so I'm speaking > from a somewhat ignorant perspective, but based on my > experience I'd rather have metal than plastic. Me neither, and ignorant could be my middle name. Generally I would tend to agree with you, but I would rather have a plastic Sigma 70-200/f2.8 than the way too heavy FA 80-200/f2.8 which I would just leave at home to save me from back problems! I would certainly rather the Mz-S to the plastic bodies, but then magnesium has a lot of the advantages of both.
