"Thermal Stability"

[Huck Finn]

This question got lost on another thread, so i'm giving it its own post . . . which is probably what I should have done to begin with.

When yesterday's mail arrived, it brought the latest B&H catalogue & I found the follwoing curious comment listed as one of the features of the Zeiss Ikon:

"Metal body for mechanical & thermal long-term stability"

Does anyone have any idea what they're talking about?? "Mechanical stability" I understand. But I've never seen this description of "thermal stability" about a camera body before in a B&H catalogue or anywhere else. Nor does the ZI literature say anything about this. Is "thermal stability" a characteristic of all metal bodies or just the ZI? and does this mean that plastic bodies don't have "thermal stability"?

NWCanonman was kind enough to speculate that this may be a reference to carbon fiber. Any other guesses? I'm at a loss.

Huck

 

[cp_ste.croix]

Maybe it's an allusion to plastics expanding and contracting with heat changes and thus wearing the material to the point of cracking? (not that I've ever seen this in a camera)

Maybe it's an allusion to fog free glass?

Maybe it has something to do with keeping the film at a more constant temp?

Maybe it's all marketing B.S.

🙂

 

[David Kieltyka]

It sure reads like marketingspeak, but as you note no mention of this is made in Zeiss' own marketing efforts to date. 🙂 Maybe it's part of the spiel Zeiss (or Hasselblad) is providing to retailers.

-Dave-

 

[phototone]

Maybe it is referring to the ability of plastic to melt-down into unrecognizable shapes when left in direct sun on the dashboard of a car.

 

[mattg]

I'd always thought that Thermal Stability means the ability to retain particular mechanical qualities at a range of temperatures. I think in this case what they mean is what phototone said; plastic melts, goes soft, may change shape if repeatedly heated and cooled etc etc.

Carbon Fibre has many diffferent sets of properties depending on the manufacturing process and resins used etc. It can be thermally stable and unstable depending on the resin and curing. One thing it almost always is is brittle when used by itself so I don't think we'll be seeing all carbon cameras.

 

[Huck Finn]

Thanks, guys. I hate when the marketing people do this, i.e. list as an asset something that doesn't differentiate the product from all other similar products . . . or present what may be a unique feature with no explanation. All it does is create confusion. Maybe I'll e-mail Hasselblad . . . but not this weekend.

Huck

 

[gefoto3]

Hi guys. Mattg has the right idea. Being a chemist I work with pharmaceuticals and test the thermal stability of product using temperature/humidity chambers. All materials have a physical property called coefficient of linear expansion. Things expand when heated and contract when cooled. Plastics do the same. You would want to keep this coefficient as low as possible so mechanical parts function as designed and no molecular breakdown occurs. I don't think plastic materials hold thier molecular integrity as well or as long as metals in wide temperature ranges. One way to test is to put the whole camera in a temperature stability chamber like the ones I use and keep it there for 6 months at 120 degrees and see if there is any malfunction. I would think that plastics would not hold up as good as metal. Zeiss is only saying they chose a metal body for just this reason. All metal cameras will share this design qualification. Some better than others depending on the choice of metals used. This isn't to say plastics don't have thermal stability because they do. Maybe just not as long term or extreme temperatures. The only way to know is to test using a temperature stability chamber. Sorry for my ramblings 🙂 I agree with Huck Finn. It probably should not have been mentioned that way because this is something I would place a bet all cameras makers perform on their camera designs and they know the thermal properties of the bodies under certain temperature swings.

 

[Huck Finn]

I e-mailed Hasselblad with this very question. Here is their reply:

"This is a Zeiss claim (It's in the brochure too.) and we raised the same question from Hasselblad.The meaning is that by using proper design & materials, the camera will also stand high temperatures (for example, lying in the car window & heating up a lot) and low temperatures."

Sounds like much ado about nothing. Strange that B&H would lift this feature from the brochure from among all the ones they could have chosen.

Huck