The longer answer is: Seems a lot of folks were asking Induro about a maximum focal length or lens weight for the various Gimbal Heads so Induro added this information to their web site just recently. Because there are so many different factors that come into play: camera body/lens combo, battery grip installed or not, flash attached or not, the length of the lens, etc they decided using a focal length was the best way to make a recommendation.
While I was waiting to hear back from Induro I did some of my own investigation. I wanted to see how the weight of my EF 400 lens compared to the EF 300 f/4 and EF 300 f/2.8. According to the specifications I found on the B&H Web Site my 400 weighs 2.8 pounds. The 300 f/4 weighs 2.6 pounds and the 300 2.8 weighs 6 pounds. Let's assume the camera body weighs another 2 pounds that would put my 400 with body at 4.8 pounds, the 300 f/4 at 4.6 pounds and the 300 2.8 at 8 pounds. Based upon that I would say as long as your camera/lens combo weighs 8 pounds or less the GHBA Gimbal Head should support it just fine. One very important caveat is that you are using a lens that has a tripod collar and you're mounting it to the GHBA Gimbal Head using that and not trying to attach it using the camera body.
Here's what I'll do since I'm such a nice guy. If you have any doubt that your camera/lens combination will work with the GHBA Gimbal Head send me your camera and lens for testing and I'll let you know if it works or not :)
With the Ballhead quick release plate locked into the groove on the side of the ballhead you slide the GHBA Gimbal Head into position and lock it down as shown below. You'll also want to tighten the main tension knob on the Ballhead. You don't want the Gimbal Head moving around in the Ballhead socket while you're trying to use it.
|Induro GHBA Gimbal Head on BHD3 Ballhead|
|GHBA Gimbal Head with Canon EF 400 Lens Right Side Mount|
|GHBA Gimbal Head with Canon EF 400 Lens Left Side Mount|
I am 100% certain my birding photography has improved since I've started using a Gimbal Head. That being said is do I have any dislikes or regrets about buying it? Yes but again my dislike is one that I probably shouldn't mention but will anyway. I'm slowly incorporating flash into my birding photography and right now there isn't any kind of accessory bracket available that would allow me to mount my flash above the camera like you can with similary style Gimbal Head manufacturered by a different company. I have a son that is currently serving as an Aircraft Mechanic in the Marines (Quick shout out to all service men and women in all branches. A huge THANK YOU for your service) and I'm going to see if he can use his sheet metal skills to fabricate something for me. Of course the ultimate solution would be if Induro made one for all of their Gimbal Heads. That would make me one happy camper.
I also have one regret after buying this Gimbal Head. Had I known in advance that I would enjoy using it so much I wouldn't have bought the BHD3 BallHead and GHBA Gimbal Head. I would have gone right for either the GHB1 or GHB2 Gimbal Head instead. Using a Gimbal Head has changed my game that much that I always want to shoot with it. For now, though the combination of Ballhead and separate Gimbal Head gives me the best of both worlds. When I do get that Canon Super Telephoto I'll probably buy the GHB2 Gimbal Head to go along with it but we'll see by the time I can buy that lens Induro may have come out with a GHB3 or something else that would work better for me.
Cost for the Induro GHBA Gimbal Head - $204.00. The link below is for the Ballhead on Amazon. If you use it to purchase one I'll receive a little commission and you'll get an easy to use Gimbal Head that you'll love as much as I love mine.