Today’s Question: Am I missing something, or should I be able to lock the zoom for my lens at any focal length? Why does the lens only lock when it is at the shortest focal length? I think it would be helpful to be able to lock at the longest focal length, or anywhere in between.
Tim’s Quick Answer: Most zoom lenses only lock at the shortest focal length, in large part so the lens can be stored more safely without the risk of the lens extending or contracting. However, there are some zoom lenses that enable you to lock the zoom at any focal length.
More Detail: Many zoom lenses don’t have a locking mechanism at all, and most of those that do have a locking mechanism only allow you to lock the lens at the shortest focal length (the smallest overall size for the lens). This can help protect the lens in storage or in transit. I find this to be most useful when I’m carrying a camera and lens using a camera strap, and I don’t want the zoom lens to extend while I’m walking around.
Of course, a lens locked at the shortest focal length doesn’t provide as much utility as we might hope for. Being able to lock at any focal length could help prevent “lens creep”, for example, with lenses that are a little loose especially when pointed downward toward a subject.
However, some lenses do enable you to lock the zoom at any focal length. For example, I’ve been using the Tamron 150-600mm G2 lens somewhat extensively during my current travels (Nikon version here: https://amzn.to/2pVGZ5C, and Canon version here: https://amzn.to/2GNPUzW).
This lens is an example of one that enables you to lock the zoom at any focal length. In fact, there are two locking mechanism. There is of course the “normal” lock that keeps the lens secured at the shortest focal length. In addition, however, you can lock the zoom at any setting by sliding the zoom barrel forward. When you want to shift the lens to a different zoom setting, simply slide that barrel backward again to unlock.
There are other lenses that incorporate this same feature, and I do find it helpful in a variety of situations. That said, I have found that a relatively small number of zoom lenses actually incorporate this clever option that enables you to lock the zoom at any focal length setting.