For those readers who’ve never actually held a big birding lens in their hands, a reality check may be in order if you’re thinking of buying one of these monsters.  The largest of the  super-telephoto lenses used by pro bird photographers are not only expensive, they’re also heavy and awkward to carry around in the wilderness when searching for birds.  The image below shows the author carrying his big 600mm f/4 lens, tripod-mounted and with a large flash extender attached, over one shoulder while a smaller (but still sizeable) 400mm f/4 lens with external flash unit and flash extender hangs from the other shoulder.




In terms of carrying the largest lenses—namely, the 500mm f/4, 600mm f/4, and 800mm f/5.6 lenses of various brands—the most common method is to leave the lens attached to the tripod and to pick up the tripod and sling it over one’s shoulder.  This is very, very dangerous!  As you might be able to discern from the above photo, I keep a firm old of the gimbal head that the lens is attached to whenever carrying the tripod-mounted setup in this way.  There’s a reason for this.
    Over the years I’ve heard a number of first-hand accounts involving the loss of large telephoto lenses when carried as shown in the photo above.  Two warrant mentioning here.  The first involved a photographer using the same lens shown above (the Canon 600mm f/4 lens, which runs about US $8000) mounted on a cheap monopod.  When the chap hoisted the lens onto his shoulder, the tiny screw holding the monopod’s head in place on the end of the monopod snapped, allowing the lens and camera to fall to the ground.  But the photographer was on a bridge over “troubled waters”, so to speak.  The lens and camera rolled off the bridge and into an alligator-infested lake.  The photographer had to hire professional divers to brave the reptiles’ domain and retrieve the lens, which Canon later proclaimed was unfixable.  This story was posted on an internet forum by the photographer himself, who provided photographic documentation of the recovery effort by the professional diving team.
    The other story was related to me by a fellow photographer in Ohio.  While birding in some remote location with his Sigma 800mm lens and Nikon D700 digital camera, he slung the tripod-mounted rig over his shoulder to find that the lens bracket wasn’t totally secure in the tripod head’s quick-release clamp.  The lens and camera slid off the tripod and hurled toward the ground.  The camera was crushed by the force of impact, and completely demolished.  The 800mm lens snapped in half, but was ultimately repaired by the manufacturer.
    The moral of the story (or stories) is that bad things can happen if you don’t take care to carry your lens properly in the field.  Many birders simply sling their tripod-mounted lens/camera over their shoulder, apparently unaware that many tripod heads are held in place by a tiny, 15-cent screw that is likely not rated for the amount of torque applied by the maneuver.  If you’re going to use the tripod-over-the-shoulder approach, at least keep one hand firmly on the lens foot or on the tripod head, so that if the head detaches from the tripod, you’ll still have a chance to keep the lens/camera from falling to the ground.
    Another option for the super-big lenses typically used on tripods is to detach the lens from the tripod and sling it, via a lens strap, over your shoulder while you carry the tripod separately.  For long hikes I do this, while always being sure to check the strap itself to make certain that it shows no sign of coming un-fastened from the lens. 
    For smaller lenses used without a tripod, it’s a good idea to make sure you’re using a dependable strap.  I once had a strap break just as I was setting a lens on the seat of my car (it wasn’t damaged).  It’s worth spending an extra $10 or $20 for a robust strap to protect your $1000+ lens.  In terms of actual use in the field, I prefer to sling the strap over my shoulder rather than my neck, since a heavy 400mm lens around your neck can cause some seriously sore muscles by the end of the day.  If you do sling your camera/lens over your shoulder via the strap, be extra vigilant at all times to make sure the strap doesn’t slide off your shoulder.  I only use straps with rubber backing, which provides extra friction and helps keep the strap on my shoulder.  I also keep my elbow bent at a 90-degree angle at all times when a camera is slung over my shoulder, so that if the strap slips off my shoulder it’ll at least catch onto my forearm and hopefully prevent damage to the camera or lens.