Have you ever tried changing lenses on a DSLR, in a situation where you had to keep hold of the camera the whole time? The problem is that it essentially requires three hands. You need two hands to twist off the old lens and put its rear protective cap on, and to un-rear-cap the new lens and twist it onto the camera – your non-existent third hand, meanwhile, is required to hold the camera body. Because photographers are in reality limited to two hands, they instead perform a sort of awkward juggling act, in which they risk dropping the camera or one of the lenses. The Backer Capper, however, is a product-in-development that’s designed to make the task considerably easier.
The Backer Capper system consists of replacement rear lens caps for the user’s existing lenses – each cap incorporating a strong Neodymium magnet – along with a magnet-equipped base that those caps can be pressed into. That base is strapped someplace where the user can easily get to it, such as on the shoulder strap of a camera bag or backpack, or on a belt.
When it’s time to change lenses, the photographer just uses one hand to twist the old lens off of the camera, and then onto its base-mounted rear cap. When the photographer then pulls out on the lens, the magnets release from one another and the base lets go of the cap, so the protected lens can be put away. With the new lens, the process is simply reversed – its rear cap is pressed into place on the base, and stays there when the lens is subsequently twisted off and put onto the camera.
Needless to say, you could also just let your camera hang from a neck strap while you change lenses. Not everyone likes using those straps, however.
The Backer Capper is the creation of San Jose-based company camarush, and is currently set up to work with most Nikon and Canon lenses. Other models are on the way.
Its makers are currently raising production funds on Kickstarter. A pledge of US$20 will get you a set that includes two caps, when and if the product reaches production. Larger pledges will get you more caps.
Additional information is available in the pitch video below.
Source: Kickstarter
Why? "Needless to say" I've never met anyone else with a disability of using such basic common sense, until I read this article.
so... what's the point?
I use a Spider holster.
Back on topic: I would never trust the weight of a f/2.8 zoom to a little magnet.
Back in early 70s Canon had a very innovative design for their F series cameras. The mounting ring could be turned to release the lens from camera and it would click into open position. The lens simply had to be pressed against the rear cap which released the spring loaded mounting ring on the lens to turn and hold the cap in place.