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In defense of plastic

But thinking about it ... I have my eye on an Aria.

Don't scare me about the plastic!
 
I'm not going to get into the discussion of the physics here (seriously busy at work today) but I will say that the only serious drop that has befallen any of my lenses occurred when my Canon 85/1.8 flew out of a bag from nearly shoulder height and landed on stone. If it wasn't for the presence of the reversible plastic hood (in its reversed position) and a Hoya UV filter with any ally ring, I have no doubt that the lens would have been history. The thought of my Zeiss 85/1.4 undergoing the same sort of abuse makes me wince. There's no way it would have survived it. In this case, I believe both the design and the material of the hood played a part in minimising the shock to the bits that matter.

-= mike =-
 
I would add my angle of view to this. I would not like to repeat the same what was said above, so say this:fully metal bodies very often have a more quiet shutter.
The movement of the inside mirror is a existing danger for the final sharpness of photography, especially when body is plastic only. (for ex&le y fx-3 has 1/30 as a critical ex.time, although anyway belongs to quite good designed cameras- with comparing to other similar models).
This danger is very reduced with big metal body. Polycarbonate cameras also have limitations- with using of heavy lenses, or with using a tripod. I even saw a camera fully carbonate- bayonet and loading film track too...(other producer)
Nothing beats big heavy camera in stability, only bigger ones- or medium or large format! :)Weight has a sense... I am pretty much convinced that with metal body you achieve higher results, how much *higher* that's a question and a matter of direct comparing.

Plastic ones have another advantages for what are bought-menitioned already above.
just my observation, pavel
 
Hi Pavel,

"The movement of the inside mirror is a existing danger for the final sharpness of photography, especially when body is plastic only. This danger is very reduced with big metal body."

I disagree, that is if you are talking about stability of the lense mount/mirror/focusing screen/film plane (which the assembly is called the mirror box) assuring accurate focusing. The body could be cardboard...it is the mirror box that is important, and I believe the Contax cameras that have polycarbonate bodies have metal mirror boxes, so this issue is mitigated at least with Contax.

If you are talking about sheer weight to d&en the shutter etc. yes, I agree, and a heavy lense like the 85/1.4 I believe makes for a wonderful d&ener on my Aria...and I have no problem shooting at 1/15 at 1.4 with that lense.

Regards,

Austin
 
Hi Pavel

I think Austin has put it well. A heavy camera body will certainly decrease vibration due to mirror movement. But the simple solution to this problem is not to build a 5 kilo body; just provide a means to lock up mirror. Something that many manufacturers have neglected of late.

Regards,

Mike.
 
Physics? Inertia? Young's modulus of elasticity? D&ing factors? d = ut + 0.5ft*t ... All Greek to me!
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All I know is that plastic (sorry, polycarbonate) don't show brassing, can be polished with care to take out minor scratches that would show base metal if the same amount of polishing was applied to metal.

It doesn't take off as much skin when it sticks to your hand in sub-zero temperatures.

Can take minor knocks and rebound without being permanently deformed.

On the other hand there is also a disadvantage ...

Can take minor knocks and rebound without being permanently deformed

(What! Deja Vu?)
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..................

I have seen circuit boards hidden under the pentaprism that show impact damage, even though the outside plastic showed no damage at a cursory glance. Only on close inspection did the plastic show that the camera had taken a fair "whack"!

I did chuckle at the thought of a RTS III or an AX made of wood .... in fact I still am .... better still, an ND in finest rosewood ..... don't start me off again, please.

Cheers, Kyocera Kid.
 
Sorry ... didn't mean "under" the pentaprism .... meant under the pentaprism housing .... if you see what I mean!

Cheers, Kyocera Kid
 
Fellow Photo-enthusiasts,

Choice of materials is only one aspect of good engineering. Which is best really depends on what your criteria for "best" is.

Then again, if your criteria is, say, survivability from a one meter fall onto a cement floor, then choice of material still is only one design parameter. In the case of a fall, damage does not depend on f=ma. The force on a body is relatively the same anywhere close to earth whether stationary or falling. The only time the force would be different would be if you are in space or on another planet. What is more of a concern is the difference of potential energy from a body at rest one meter from the ground to the potential energy from the same body at rest on the ground.

The basic law of physics says that energy must be conserved or rather the potential energy lost in the fall of a body must be converted into either heat, noise, or deformation of the material (this doesn't cover bouncing which would be converting the kinetic energy back to potential energy minus losses). Clearly, modern polycarbonate materials are more efficient at converting kinetic energy to heat or in effect absorbing the shock. Metal parts will tend to deform or transfer the energy. Again, either the energy causes the metal to bend or break or it is transfered to whatever is attached to the metal or it is returned to potential energy.

Survivability for a metal camera will depend on whether the transfer of energy can be dissapated by the rest of the non-metal parts or if the deformation itself, if any, causes the camera to malfunction. In the former case, the survivability will depend on the non-metal parts and metal parts inside the casing that are more fragile.

Ultimately, it is not cost effective to design a camera based on crash-survivability alone. Size and weight must also be considered. If they were not considered then the best camera to take an impact would be a massive sorbethane blob that would covert all kinetic energy to heat or massive metal exoskeleton that would deform but not transfer energy to the innards.

Obviously, the best camera has metal parts where you need 'em (where rigidity and wear are factors) and polycarbonate parts where it makes sense (size and weight, impact absorption, et al). All this in a package that isn't too expensive or made of unobtainium.

For those who have a look at the Aria, it is a beautifully engineered camera that is very compact and lightweight and mounts wonderful lenses.

Suggestion: don't drop your camera.
 
Perhaps I can add a piece of anecdotal evidence.

Last week I dropped an RTS with the 5fps drive and power pack coupled to a 300mm f2.8 Tamron from shoulder height onto a carpark. The lens which took most of the impact has a very large dent in the ring but the old RTS and its huge motor drive and power pack are fine. It has resulted in some damage to the focusing screen which isn't a major issue. There is a large dent in the car park.
 
A camera in rosewood would be beautiful but not very stable when humidity changes.
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Seriously, though, I appreciate my Aria when I travel. I carry so much as it is, having the Aria allows me to carry three primes in a compact pack. The camera is either around my neck or in my well padded bag. Therefore, I didn't consider its survivability in a fall to be a consideration when I bought it.
 
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