So what makes a housing rated to 200 feet vs 130 feet?

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reefvagabond

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So I have a polycarbonate ikelite and canon housing for the same camera. The ikelite is rated to 200 feet (60 meters) while the canon is rated to 130 feet (40 meters). But after reviewing both housing, I'm left wondering what exactly makes one rated to 200 feet vs 130?

The ikelites springs seem stronger so maybe the buttons won't get pressed at 200 feet, and its buttons are made of metal. But in terms of stopping leaks i don't really see the difference. What am I missing?
 
You need to ask the manufacturers. But the simplest guess is, the 130 ft rated housing can simply crack at 200 ft.
 
i would be most worried about the pushbuttons leaking or the housing door deflecting and allowing a leak.

polycarbonate is pretty tough so i do not think you need to worry about cracking as it will bend first. maybe overtime a thinner housing would craze and then (if ignored) eventually crack?

this link https://theses.lib.vt.edu/theses/available/etd-08142000-13410044/unrestricted/etd.pdf discusses crazing in fighter jet canopies and observes that finger oils contribute to crazing.
 
What Bill says. it would be a poor housing indeed that cracked at 200 feet and not at 130 feet. If it were that fragile, it certainly wouldn't take any of the normal bumps and bounces of a dive.

It's typically the springs for the buttons. A consumer who is happy with a 130 foot housing is probably not going to want hard to push springs that will return the buttons at a deeper depth. Since most photography takes place in recreational depth to use natural light, etc, the button springs are made to be comfortable to use where the target audience is.

For years, Nauticam refused to depth rate a housing deeper than 300 feet. It has nothing to do with the strength of the housing, but with the procurement of button springs for a very limited market.

A housing manufacturer who makes a 130 foot depth rated housing is playing to his strengths.
 
In some more simple housings, like some housings made for GoPro that I have seen, the critical point is the window in front of the lens. Unlike most of the parts of a housing, that window cannot be convex or have any reinforcing thicker parts, but has to be absolutely flat and uniform. At some pressure the material starts to give in and the window bends inward, which of course ruins its optical properties.
 
I've seen polycarbonate vials crack in high speed centrifuge. Every material has its limits.
 
I've seen polycarbonate vials crack in high speed centrifuge. Every material has its limits.
interesting. any idea how this relates to scuba housings?

i know nothing about centrifuges except that they spin.
 
interesting. any idea how this relates to scuba housings?

i know nothing about centrifuges except that they spin.
Just like I said, every material has its limits. Do not assume that if it is rated to 130 it won't crack at 200. Maybe it will.
 

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