Dumb Question...

[rocketdesigner]

Is it a bad thing to leave my 24-70 lens attached to my t2i when I am done shooting and for a few days? Should you always remove your lens when you know you might be awhile before you use your camera again?

Just thinking in leaving it on I might be somehow damaging the lens due to its weight ...

[Canon Rumors]

There's no problem leaving lenses attached. It will marginally help reduce dust getting inside the mirror box.

[CanineCandidsByL]

While it probably bad to disagree with the administrator  , I'll say it can be bad, but only a little little bit. Vs the extra chance of dust getting in, I'd leave the lens on except when swapping lenses. The risk, if any, comes from the torque the weight can apply to the mounting ring.  Like many, I have the tales of a friend of a friend, but haven't seen myself, of a lens ripping the body mount ring off. But its not happening enough that I'd worry about it. Just as a matter of preference, I keep my camera body and lens equally supported in my bag when not using. That effectively eliminates the risk and makes sure the camera is protected when not in use.

Besides, if your a gadget freak like many here, its just another perfect reason to upgrade.

[rocketdesigner]

That's what I was afraid of also ... the weight of the glass and possibly harmful torque. But as you mention, I try to set it in my bag so there is support under the lens (usually just by placing it in the bag sideways).

Maybe it boils down to how often I actually use it: if I know I won't be shooting for a week or two, take the lens off?

[CanineCandidsByL]

I have a canon A1 (think 1980s) sitting supported in a bag with a 300mm lens attached. Its been that way for at least a year and I'm not sweating it. I wouldn't take the lens off.

[neuroanatomist]

Maybe it boils down to how often I actually use it: if I know I won't be shooting for a week or two, take the lens off?

Seriously, I think you're worried about nothing.  If there's going to be torque on a lens mount, it's more likely to occur as you swing the camera around while you're using/carrying it than when it's sitting in a bag.  Any current Canon body has a lens mount that's designed to take any EF lens.  If a lens is so heavy that it would put undue stress on the lens mount to support the lens by the camera body, Canon would provide an alternative means of support.  They do that for the supertele lenses (strap lugs on the lens barrel, non-removeable tripod mounts), the lightest of which is the EF 400mm f/4 DO IS at 68.5 oz (1.94 kg), but not for next-heaviest lens in the lineup, the EF 28-300mm f/3.5-5.6L IS at 59 oz. (1.67 kg).  So, the inference is that a lens weighing 60 oz. or less will not place undue stress on the lens mount.  The 24-70mm, despite sometimes being referred to as the 'wedding brick,' is a mere 33.5 oz (0.95 kg) - nothing to worry about in terms of stress on the lens mount.

[KurtStevens]

What you should be worried about is the torque from the 50mm 1.8.  Talk about a beast.

Leave the lens on, and you can pull your camera right out of your bag without having to tell everyone wait, while I find my lens and put it on and blah blah... know what I mean?

[Mt Spokane Photography]

I would never worry about the lens staying on the camera.  My 100-400mm l lived on my 1D MK III for a couple of years, and now stays on my 7D.

I also have other heavier lenses, none of them heavy enough to worry about leaving on a camera, not even a 600mm L.  The really big lenses support the camera, its the lens you carry and mount on the tripod.  The camera is not heavy enough to damage a lens or itself.

[iris chrome]

@neuroanatomist, it's only semantics and I'm probably just nitpicking but the EF 28-300mm f/3.5-5.6L IS would actually be the next-lightest lens in the lineup 

@rocketdesigner and CanineCandidsByL, is there going to be continuous stress and torque on the mount from leaving the lens on all the time? Definitely. Is this stress going to cause any damage to your camera and mount? Unless you've got one of the heavier lenses mounted on your camera, absolutely not. The tolerance level of your camera mount is beyond just having a lens attached while your camera is sitting idly.