April 18, 2014, 07:56:53 AM

Author Topic: Are Metal Mounts Better Than Plastic?  (Read 8318 times)

WPJ

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Re: Are Metal Mounts Better Than Plastic?
« Reply #60 on: January 05, 2014, 10:35:33 AM »
Don the pressure in water or atmospheric pressure is additive every 33' under water.

so 0-33 feet below the water line is the same pressure which is the same we have in land
at 34-66feet it doubles the pressure at land or sea level.

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Re: Are Metal Mounts Better Than Plastic?
« Reply #60 on: January 05, 2014, 10:35:33 AM »

Don Haines

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Re: Are Metal Mounts Better Than Plastic?
« Reply #61 on: January 05, 2014, 10:52:12 AM »
Don the pressure in water or atmospheric pressure is additive every 33' under water.

so 0-33 feet below the water line is the same pressure which is the same we have in land
at 34-66feet it doubles the pressure at land or sea level.
But we start off  at one atmosphere of pressure (at sea level anyway) and the pressure is relative to the inside of the unit.

Assuming sea level and no weird atmospheric conditions like hurricanes, etc....
1 foot above water - 1 atmosphere
at water level - 1 atmosphere
3.3 feet below - 1.1 atmosphere
16.5 feet below - 1.5 atmosphere
33 feet below - 2 atmosphere

2 atmospheres is where most of the P/S underwater cameras are rated for. It is one atmosphere higher than the internal pressure of the unit.

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privatebydesign

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Re: Are Metal Mounts Better Than Plastic?
« Reply #62 on: January 05, 2014, 10:53:30 AM »
Don the pressure in water or atmospheric pressure is additive every 33' under water.

so 0-33 feet below the water line is the same pressure which is the same we have in land
at 34-66feet it doubles the pressure at land or sea level.

Go check your PADI RDP, or the open water course book, each 33ft is plus one atmosphere; so 33ft below the surface at sea level is 2 atmospheres, or 28psi. The first 33ft is not free the water column still has the air column on top of it.
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WPJ

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Re: Are Metal Mounts Better Than Plastic?
« Reply #63 on: January 05, 2014, 10:56:36 AM »
Don the pressure in water or atmospheric pressure is additive every 33' under water.

so 0-33 feet below the water line is the same pressure which is the same we have in land
at 34-66feet it doubles the pressure at land or sea level.
But we start off  at one atmosphere of pressure (at sea level anyway) and the pressure is relative to the inside of the unit.

Assuming sea level and no weird atmospheric conditions like hurricanes, etc....
1 foot above water - 1 atmosphere
at water level - 1 atmosphere
3.3 feet below - 1.1 atmosphere
16.5 feet below - 1.5 atmosphere
33 feet below - 2 atmosphere

(2 atmospheres is where most of the P/S underwater cameras are rated for)

ya something like that, but it is more like at 16' is like 1.3, at 33 its 2

hence staying jn 0-33 or 33-66 is relatively easy to seal after that it get much harder to seal

Don Haines

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Re: Are Metal Mounts Better Than Plastic?
« Reply #64 on: January 05, 2014, 11:06:17 AM »
Don the pressure in water or atmospheric pressure is additive every 33' under water.

so 0-33 feet below the water line is the same pressure which is the same we have in land
at 34-66feet it doubles the pressure at land or sea level.
But we start off  at one atmosphere of pressure (at sea level anyway) and the pressure is relative to the inside of the unit.

Assuming sea level and no weird atmospheric conditions like hurricanes, etc....
1 foot above water - 1 atmosphere
at water level - 1 atmosphere
3.3 feet below - 1.1 atmosphere
16.5 feet below - 1.5 atmosphere
33 feet below - 2 atmosphere

(2 atmospheres is where most of the P/S underwater cameras are rated for)

ya something like that, but it is more like at 16' is like 1.3, at 33 its 2

hence staying jn 0-33 or 33-66 is relatively easy to seal after that it get much harder to seal
Yes.... we are saying the same thing :)

and at the risk of being publicly flayed on a canon forum... the Nikonos!!! Now that was a waterproof camera :) Add on an Ikilite strobe and you had a flash so bright you could annoy people in submarines :) :)
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WPJ

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Re: Are Metal Mounts Better Than Plastic?
« Reply #65 on: January 05, 2014, 11:07:22 AM »
Don the pressure in water or atmospheric pressure is additive every 33' under water.

so 0-33 feet below the water line is the same pressure which is the same we have in land
at 34-66feet it doubles the pressure at land or sea level.
But we start off  at one atmosphere of pressure (at sea level anyway) and the pressure is relative to the inside of the unit.

Assuming sea level and no weird atmospheric conditions like hurricanes, etc....
1 foot above water - 1 atmosphere
at water level - 1 atmosphere
3.3 feet below - 1.1 atmosphere
16.5 feet below - 1.5 atmosphere
33 feet below - 2 atmosphere

(2 atmospheres is where most of the P/S underwater cameras are rated for)

ya something like that, but it is more like at 16' is like 1.3, at 33 its 2

hence staying jn 0-33 or 33-66 is relatively easy to seal after that it get much harder to seal
Yes.... we are saying the same thing :)

and at the risk of being publicly flayed on a canon forum... the Nikonos!!! Now that was a waterproof camera :) Add on an Ikilite strobe and you had a flash so bright you could annoy people in submarines :) :)

love it.....

neuroanatomist

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Re: Are Metal Mounts Better Than Plastic?
« Reply #66 on: January 05, 2014, 11:49:28 AM »
That pretty well sums up DSLR "weather-sealing". It will survive being in the rain, but as soon as there is any pressure, the game is up. Splashproof is a much better word....

Well, I can't speak for you, but the weather has never submerged me in water.  Jumping in a pool or diving into the ocean aren't 'weather' - and anyone who does so holding their weather-sealed dSLR+lens expecting them to survive is an idiot.

So, I think 'weather sealed' is an appropriate term.  However, I agree that testing to an industry standard would be much better.
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Re: Are Metal Mounts Better Than Plastic?
« Reply #66 on: January 05, 2014, 11:49:28 AM »

marcel

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Re: Are Metal Mounts Better Than Plastic?
« Reply #67 on: January 05, 2014, 11:58:58 AM »
Plastic mounts on the lens and in the camera. The camera worked also with the extremely heavy EF 28-80 f2.8-4L with no problem, on tripod.
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sagittariansrock

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Re: Are Metal Mounts Better Than Plastic?
« Reply #68 on: January 05, 2014, 12:20:33 PM »
Don the pressure in water or atmospheric pressure is additive every 33' under water.

so 0-33 feet below the water line is the same pressure which is the same we have in land
at 34-66feet it doubles the pressure at land or sea level.

It's not that the pressure JUMPS from 1 atm to 2 atm and so on every 33 feet. It's a continuous increment. At 16 feet it is 0.5 atm, for example.
Anything that doesn't specifically say "water resistance to x feet depth" should not be intentionally immersed completely, no matter how "weather sealed" it is, for any length of time. A very little water pressure is required to allow ingress unless the seals are designed to withstand pressure and are not simple foam rubber gaskets or "scotch tape".
Never sarcastic, just misinterpreted sometimes.

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AvTvM

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Re: Are Metal Mounts Better Than Plastic?
« Reply #69 on: January 05, 2014, 12:29:05 PM »
That pretty well sums up DSLR "weather-sealing". It will survive being in the rain, but as soon as there is any pressure, the game is up. Splashproof is a much better word....


Well, I can't speak for you, but the weather has never submerged me in water.  Jumping in a pool or diving into the ocean aren't 'weather' - and anyone who does so holding their weather-sealed dSLR+lens expecting them to survive is an idiot.

So, I think 'weather sealed' is an appropriate term.  However, I agree that testing to an industry standard would be much better.


agree 100%. Appropriate Industry standard exists.

On their german website Ricoh rates its Pentax K-50 DSLR as "protected according to IPX2" ... which would not mean much, since an ingress prtotection rating of IPX2 only means "Protection against direct sprays of water up to 15o from the vertical." 
http://www.engineeringtoolbox.com/ip-ingress-protection-d_452.html

While I do not know, whether or not Ricoh has indepentently tested/certified the K-50 or just makes a claim, I juist love it that for once a camera manufcaturer quotes a specific and clearly understood ingress protection class.

To my knowledge Canon has never provided such a rating, not even for its super-expensive "fully weathersealed" 1-series cameras.  To me ... "professional" grade ... would mean clearly class IP67 ingress protection (against both dust and water; anything less allows for limited ingress of water and/or dust). Currently I would expect a Canon 1 D X with body cap on (no lens!) to be ingress protected at about IP 54.

Of course a rating should also be provided for any "ingress protected" ("L") lens. Along with an assurance that any given camera body + attached lens will adhere at least to the lower IP number.

Alternatively I would also be happy to see (even tougher) MIL standards quoted, if the manufacturers want to really boast about their "professional grade" stuff. :-)

In Europe I would love the EU commission to regulate the matter and require manufacturers to provide a certified ingress protection standard for any consumer product [which includes any camera and lens we are discussing here] if any claims regarding "wheather protection", "sealing" or "professional grade" or similar are being used in advertising a product.

acoll123

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Re: Are Metal Mounts Better Than Plastic?
« Reply #70 on: January 05, 2014, 12:55:32 PM »
Ironically, I had my new conn 24-70 II break at the mount a few months ago after being dropped. In the article, Roger said it had a metal mount but it appeared to be plastic to me . . .  I was actually glad it was plastic and broke where it did. None of the optics were broken and the repair from CPS only involved replacing the mount ring . . . still $350 but cheaper than a new lens or glass. I think engineering a planned "break point" into a lens is a very good design decision and probably precludes more catastrophic damage.

Andy

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Re: Are Metal Mounts Better Than Plastic?
« Reply #71 on: January 05, 2014, 02:17:32 PM »
The more I think about the original title question, the more I come to the classic engineering answer ie: it depends...

Best for what? Strongest, lightest, most thermally stable, most rustproof, most bombproof or... cheapest...

As an aside, I had a look at a 18-55 kit lens and it looks like it is ABS plastic all aroud. That would seem like a good material as it is quite stiff, has  high impact resistance and is easily moulded to good precisions.

Personally, I would not mind having plastic mount (not bayonet) designed as a fuse, but I also concede that 'made to break easily at the mount to prevent internal damage if hit' won't make for a strong marketing punchline.
What a mess, my camera's sensor is full of massless particules that keep on trying to behave like waves!

RustyTheGeek

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Re: Are Metal Mounts Better Than Plastic?
« Reply #72 on: January 05, 2014, 02:18:30 PM »
Plastic comes in many forms and grades... If it is the right material for the job, then it is the right material.... In some cases, plastic is superior to metal, in other places it is inferior.

You can not treat all plastics the same. Just like tin is different from titanium, so are the plastic parts of your lens different from a child's sippy cup.

I think it would be cool to see a Canon L lens made from a child's sippy cup.  (Complete with the bright colors!)  It would be great for shooting child portraits.  And when not mounted to the camera, it could double as a pacifier for toddlers.   :D
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Re: Are Metal Mounts Better Than Plastic?
« Reply #72 on: January 05, 2014, 02:18:30 PM »

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Re: Are Metal Mounts Better Than Plastic?
« Reply #73 on: January 05, 2014, 02:27:31 PM »
And then for weatherproof and professional grade claims, these kinds of empty phrases are all around for each and every products that we are advertised. It is hard to find an objective claim in any publicity. Not that we should not be unsatisfied of the situation, but I think it is a general issue and would be hard to prevent through advertisement regulations.

I mean consumers bite, so the lines are going to be cast...
What a mess, my camera's sensor is full of massless particules that keep on trying to behave like waves!

RustyTheGeek

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Re: Are Metal Mounts Better Than Plastic?
« Reply #74 on: January 05, 2014, 02:28:55 PM »
Great article.  I worry about 3 things with my lenses. 
1. fungus. I live in a very humid environment
2. Will the IS element fail?
3. Will he AF element fail?

You forgot #4.  The risk of throwing the lens at the subject because they won't/can't pose or smile.

OK, I'm feeling kinda mean today.  Shoot me.   ;)
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Re: Are Metal Mounts Better Than Plastic?
« Reply #74 on: January 05, 2014, 02:28:55 PM »