The backpack style camera bags are orientated so the lens hangs down. I wouldn't carry a camera by hand with lens attached handing down, meaning I wouldn't hold it by the camera body, rather by the lens. Also, if I carry a camera in the bag the lens cap is always attached.
Not very concern about it. Random put it in the insert bag.
me too, Lowpro classified 200AW, no matter 70-200 or 24-70., always lens facing down. But good thing is the inside partition pad actually support my camera body and the lens actually don't touch the base of the bag.
the only problem I always have is: the lens cap is so easy to fall out. ( I rarely put my lens hood on)
the only time I put camera and lens sideway is when I carry only one camera with one lens in one bag where space is no problem for it to lay down comfortably.
There you have it. "Hanging" is the key here. Lens down with the weight of the camera body supported on either side so that the weight of the lens hangs on the lens mount. If the lens rests on the bottom of the bag and the weight of the camera is supported by the lens, where is the weight of the camera actually resting? On the lens zoom stop? On the lens focus stop? If the bag is thumped down on the floor, there is a lot of inertia in the camera body. The lens was never designed to support the camera in this way.
Graham, what about the other way round. Your camera weighs a lot less than let's say a 70-200mm f2.8. What do you think 1.5Kg of lens weighing down on the camera/lensmount does opposed to 0.5-0.8Kg of camera?
Just one small thing to keep in mind with "lens down, camera attached"; If you have a UV filter attached to the lens, and a lens cap on the end, a bit of a "jolt" can drive the lens cap into the filter and break it (been there, done that).
As for the rest of the argument, it's "pie in the sky" in my opinion. If you put a camera and lens combo in a padded bag and then put the whole lot in a tumble drier you MIGHT break a mount, but even then I doubt it. My 70-200/2.8 is often hanging from my cameras (which are inturn hanging from my hand in a hand strap); it doesn't bother it in the least.
I do the same thing. Just walk around with my 70-200mm attached to the camera hanging by the shoulder strap. Hell, I even run around venues (mainly track and field events) with the camera flopping everywhere. It's been three years of doing that and I see nothing on the mount that has me the least bit concerned.
CS
It's not the weight, it's the inertia. The camera mount is bolted directly to the camera body chassis, be it metal or poly. There are no moving parts there. The lens barrels are not bolted to anything, and come to rest on their adjustable stops, which are not designed to support any mass (weight) at all.
I certainly don't know the answer to the question, but I think Graham has clarified what the question IS. As I tried to imply in noting that my Tamrac holds the camera lens down but supports the camera body, the issue is not position; it is where the weight is supported. The OP's question, as I understand it, is about supporting the camera's weight on the lens barrel.
I also think that Graham is right that mounts are not the issue. They are solid, have no moving parts, and are clearly built to handle substantial weight and torsion. The question, it seems to me, is the focus and zoom mechanisms. My camera body weighs 860 g (close to 2 pounds). That is a fair amount of weight at rest, but it is a lot more force if decelerated, e.g., putting the bag down abruptly. So it seems to me that the question--to which I don't have an answer--is whether the lens mechanisms can handle that force.
Hero's question complicates matters. The 70-200 f/2.8 IS weighs about 1.5 kg -- far more than even my fairly heavy camera body. It is only the portion of the weight that is above the zoom ring that would matter. I assume that weight is still more than my camera body. So it seems to me that he has a good question: if supporting the rig by the lens can cause damage, why wouldn't similar damage arise supporting the camera upright, resting on the camera back? My packs don't do that either, but I wouldn't have given it a moment's thought if they did.
I think I won't worry about this one.
Graham, weight, or rather mass is an intricate part of inertia. if it weren't for mass we wouldn't have to worry about inertia.
And as sturdy as the mounting plate on a camera seems, it's not. It's quite a delicate high-precision part.
One of the most common side-effects of a frontal impact, aside from the obvious scratches (to the front element), is a misalignment of the mounting-plate of the camera. Not damage to the barrel or the mechanics of the lens. Only the cheapest of lenses that expand while focussing often suffer damage to the focussing unit. Most other lenses will, in their collapsed state, transfer any impact force to the more sturdy outer barrel and away from the more delicate inner parts.
So if you ask me, I rather put the grunt of the mass below the weakest point(s) (I mentioned the back-lcd in an earlier post) of my camera-lens combination.