A7R Plastic Flange

[Samouraï]

I think there is one thing standing in the way of the A7 series, or any E-mount lens for that matter, being a great all-lens camera: and that is the fact that the A7 has a plastic flange.

The problem is that the Metabones mounts aren't machined to a strict enough tolerance, and the edges aren't softened to protect the plastic flange inside the camera.

I had some light plastic shavings from the camera come off on the mount on my Metabones adapter. It went on fine, but was very difficult/tricky to remove from the camera. I don't think it's a serious issue, as everything is working fine, and my native FE lens isn't exhibiting any play. Over time, this could ruin the camera.

But this sort of hurts the camera for me as a professional tool. A plastic flange is just a problem waiting to happen. The more third party adapters, the more wear. There's going to be more play. And I'm sure heavy lenses won't be so forgiving as the system's small primes.

 

[Sam N]

Can you post a photo of the part you're talking about?

 

[GaryLH]

U gotta be kidding Sony. A $1700 camera body and your not using a metal mount flange !!!

Gary

 

[Samouraï]

U gotta be kidding Sony. A $1700 camera body and your not using a metal mount flange !!!

Gary

It's actually a $2300 body. A7R.

Now I could be mistaken of course. The flange might be a piece of blackened metal, but it looks like plastic and feels like plastic to me. Anyway, the mount consists of a plastic throat that also makes up part of the sandwich where the lens mount sits. The flange is a ring inbetween the leveling plate (I'm making this up, but it's the silver ring that says E-mount). And that's the mount. Here are a couple pictures. My copy is pretty well-oiled, too (weird).

 

[Sam N]

Do any native lenses or Sony adapters rub against that part? If not, I don't see how you can blame Sony.

 

[Samouraï]

No, it was a 3rd party adapter. Not Sony's fault. And it didn't do any damage besides a very small bit of plastic shaving. However, the E-mount is a delicate mount, and I don't understand why it was designed the way it was.

 

[sebastel]

the plastic parts are not relevant for the flange distance. also i don't see a problem with the long term stability, unless those parts disintegrate to fluffy foam.

the important part is the metal ring on top (the part you called "levelling plate"). this one needs to withstand mechanical use in order to keep the flange functional.

 

[Scrambler]

No, it was a 3rd party adapter. Not Sony's fault. And it didn't do any damage besides a very small bit of plastic shaving. However, the E-mount is a delicate mount, and I don't understand why it was designed the way it was.

It's basically the same design that Leica have - only with three rather than 4 links. The bayonet design has been implemented in plastic in many SLRs (Canon EOS among others) since the 80's and wear has been the usual complaint. Sony uses metal for the face of both the camera and lens mounts, in fact the entire lens bayonet is in metal even on my basic kit lens.

A mix of metal and plastic parts is a higher risk, but the design should not have metal coming into contact with plastic other than the "stop" at the end of each mounting face, as the spring which grips the lens bayonet is metal as well.

Without taking the camera body apart, I would say that the design is excellent in that it should work without any issue if all elements are in tolerance, but the camera body mount is the deliberate design weak point. Any truly excessive force would break a replaceable part rather than the lens.

Compare its ancestor, the Vectis APS SLR mount.


Vectis and E-mount APS by Scrambler@4350, on Flickr

 

[Mark Schretlen]

If you are concerned about metal vs plastic lens mounts, this is worth a read:

http://www.lensrentals.com/blog/2013/12/assumptions-expectations-and-plastic-mounts

 

[btgc]

If that part would be made of metal then there would be metal-metal friction, right? As I see it, this is more about precision of adapter and configuration of mount and adapter allowing friction anywhere except vertical surfaces.

Once I got SLR with a mount making considerable friction while mounting any lens, with fine metal particles accumulating inside. Then I stopped using that particular camera and had I expensive A7R I'd consider using particular adapter.

 

[Samouraï]

What are you guys talking about?
I was simply pointing out that if you are buying this camera to use with a bunch of third party adapters for other lenses, be careful. I have the active Metabones adapter, and it has already caused an issue (plastic shavings coming from my camera because of poor tolerances with this well-regarded metabones product). The design of the mount is partly at fault because it is not designed with wear and tear in mind.

So now I'll ask: is the mounting plate of the E-mount a ring of plastic or a ring of darkened metal. Because I can take my camera apart, but I'd rather not. It appears to be plastic to me.

 

[Samouraï]

If that part would be made of metal then there would be metal-metal friction, right? As I see it, this is more about precision of adapter and configuration of mount and adapter allowing friction anywhere except vertical surfaces.

Once I got SLR with a mount making considerable friction while mounting any lens, with fine metal particles accumulating inside. Then I stopped using that particular camera and had I expensive A7R I'd consider using particular adapter.

My Leica has a metal mount, my Canon has a metal mount, and my Nikon has a metal mount. It's common.

I bought the 400usd Metabones EF to E adapter. It's the only one of it's kind I think. But it's kind of crap for it's poor machining.

 

[Samouraï]

If you are concerned about metal vs plastic lens mounts, this is worth a read:

http://www.lensrentals.com/blog/2013/12/assumptions-expectations-and-plastic-mounts

I've read it. Not really relevant. I'm worried about the camera mount and its hardiness with metal adapters by third parties and long lenses. Not the bayonet on the lens (but I still wouldn't trust a 300mm with a plastic bayonet).

 

[btgc]

I bought the 400usd Metabones EF to E adapter. It's the only one of it's kind I think. But it's kind of crap for it's poor machining.

Not wanting to fall into technical discussions about mount/adapter compatibility, I'd want to not see plastic, metal or any other material degradation had I spent 400 greens on adapter. This isn't usd4 filter adapter, shipping included.

 

[lam]

Thanks for the heads up, not buying Metabones adapter.

 

[Scrambler]

I've read it. Not really relevant. I'm worried about the camera mount and its hardiness with metal adapters by third parties and long lenses. Not the bayonet on the lens (but I still wouldn't trust a 300mm with a plastic bayonet).

Partly because you didn't understand it? It isn't referring to the bayonets but to the block the bayonet (on the one side) and the lens body (on the other) mount into. And the relevance to this discussion is that plastic as a structural material is no more likely to give trouble than metal.

I've thrown out both my torn-down Minolta XG-1 of 1979 and the 70-200mm metal-and-glass lens I had on it, but I can assure you that the camera chassis was plastic and the lens the heaviest I have ever owned. The body mount was metal but anchored to plastic by 4 small screws. No trouble at all with that combination (a beverage poured through the camera did for it, and the lens developed terminal fungus).

Given your worry, what metal were you hoping to see?

The metal of the lens bayonet on my only native e-mount lens is aluminium (aluminum if you prefer). The metal of the $10 e-bay adapter I use is aluminium. I'm guessing the same is true of the Metabones?

If the body mount was in aluminium you would still get damage, only this time metal shavings from either the adapter or the camera.

If the body mount were in chromed brass, you would lose the chrome, if in plain brass it would (a) look stupid (b) corrode and (c) still have metal filings. If in stainless steel you would still have metal filings, but definitely from the adapter.

In Australia, and possibly other places, you would have the right to return the adapter. It is clearly not "fit for purpose." And this would not be altered if the lens mount were made of diamond-coated steel.

 

[Samouraï]

Partly because you didn't understand it? It isn't referring to the bayonets but to the block the bayonet (on the one side) and the lens body (on the other) mount into. And the relevance to this discussion is that plastic as a structural material is no more likely to give trouble than metal.

I've thrown out both my torn-down Minolta XG-1 of 1979 and the 70-200mm metal-and-glass lens I had on it, but I can assure you that the camera chassis was plastic and the lens the heaviest I have ever owned. The body mount was metal but anchored to plastic by 4 small screws. No trouble at all with that combination (a beverage poured through the camera did for it, and the lens developed terminal fungus).

Given your worry, what metal were you hoping to see?

The metal of the lens bayonet on my only native e-mount lens is aluminium (aluminum if you prefer). The metal of the $10 e-bay adapter I use is aluminium. I'm guessing the same is true of the Metabones?

If the body mount was in aluminium you would still get damage, only this time metal shavings from either the adapter or the camera.

If the body mount were in chromed brass, you would lose the chrome, if in plain brass it would (a) look stupid (b) corrode and (c) still have metal filings. If in stainless steel you would still have metal filings, but definitely from the adapter.

In Australia, and possibly other places, you would have the right to return the adapter. It is clearly not "fit for purpose." And this would not be altered if the lens mount were made of diamond-coated steel.

I misspoke then, my apologies. I will say, however, I don't know of any other currently produced "professional" cameras that employ a plastic mount. Besides that, I can understand wanting the mount to be the easily breakable part of the camera (as someone said above), in case one were to drop their camera (breaking the replacable bayonet/mount is preferable to bending something structural.

edit: I read the article again, and I don't see where it talks about camera mounts being plastic. Regardless, they have no evidence that a plastic bayonet is equal to a steel bayonet. Unless we're talking next-generation plastics (which are stronger than steel), I don't buy that article. There must be a reason that cinema lenses employ steel pl flanges (it's because of durability and lateral strength).

 

[Scrambler]

I misspoke then, my apologies. I will say, however, I don't know of any other currently produced "professional" cameras that employ a plastic mount. Besides that, I can understand wanting the mount to be the easily breakable part of the camera (as someone said above), in case one were to drop their camera (breaking the replacable bayonet/mount is preferable to bending something structural.

edit: I read the article again, and I don't see where it talks about camera mounts being plastic. Regardless, they have no evidence that a plastic bayonet is equal to a steel bayonet. Unless we're talking next-generation plastics (which are stronger than steel), I don't buy that article. There must be a reason that cinema lenses employ steel pl flanges (it's because of durability and lateral strength).

The confusion you are having is clarified in the comments below the article, as well as in my comment above. The article uses "mount" to refer to the bridging element within the lens that links the bayonet to the lens body. If you look at the photos you will see that all the lenses have their bayonets removed. The author states that all these lenses, and indeed every lens he rents out, have metal bayonets, but in many cases these are screwed into plastic "mounts" within the lens.

The E-mount camera I own appears to have plastic in the location you mention. As designed it should be structural (i.e. require strength) but is not a wear surface. All the wear surfaces are metal (though mounted into plastic).

I am saying that the adapter is the issue, and this would be true regardless of the material of the inner lens mount elements you refer to. The problem is that the adapter rubs against a surface it should not. If this surface were metal, it would cause metal to be worn off into the camera body.

 

[Samouraï]

The flange inside the camera needs to touch the flange on the lens in order to maintain a tight fit, no? I don't think I would have gotten the Metabones adapter on the camera if it had a metal flange, and I certainly don't think I would have had the kind of scraping taking it off that I had with the plastic.

What's really interesting to me (and this might be the ace in the hole) is that the E-mount on the Sony camera has a healthy reserve of lubricating oil hidden in the cracks around the flange. I noticed this when I was using my goat's hair brush to clear the plastic shavings from the throat of the camera (blower wasn't doing as it was trapped where the lens flange would rest) and found oil seeping out and getting on plastic inside the throat (luckily brushes are cheap, because it's in the trash now). If the plastic was better, why the lubricating oil reserves hidden in the cracks? My metal-mount cameras have no signs of lubricating oil on the flange.

 

[Scrambler]

The flange inside the camera needs to touch the flange on the lens in order to maintain a tight fit, no? I don't think I would have gotten the Metabones adapter on the camera if it had a metal flange, and I certainly don't think I would have had the kind of scraping taking it off that I had with the plastic.

What's really interesting to me (and this might be the ace in the hole) is that the E-mount on the Sony camera has a healthy reserve of lubricating oil hidden in the cracks around the flange. I noticed this when I was using my goat's hair brush to clear the plastic shavings from the throat of the camera (blower wasn't doing as it was trapped where the lens flange would rest) and found oil seeping out and getting on plastic inside the throat (luckily brushes are cheap, because it's in the trash now). If the plastic was better, why the lubricating oil reserves hidden in the cracks? My metal-mount cameras have no signs of lubricating oil on the flange.

Don't know about the oil, but if you look closely at the camera side of the e-mount you will see that there are small metal springs inside the plastic tabs which provide the mating surface holding the lens on the camera. The other points where the bayonet and body meet are the metal ring around the front: outside and within the throat. All these surfaces are metal-on-metal. If the springs were mounted on metal tabs rather than plastic, it would make no difference.