Tight Or Gritty Rings

In some lenses, the focus and zoom rings may become a little tight, especially if the lens has been put in storage for a long time.

Dust can also get lodged in the helicoid threads. Then you will get a gritty sensation when you turn it.

Try turning the zoom and focus rings one at a time. They should move smoothly and quietly.

If the action is tight or even gritty, you will need to send the lens in for cleaning and lubrication. This shouldn't cost much though.

Loose Zoom Action

Push-pull type of zoom lenses have a tendency to develop a loose zoom action over time. Try turning the lens end over end. If the zoom action is loose, the zoom ring will move of its own accord. No, it's not a poltergeist. It's just a loose zoom action.

Although this will not affect the lens optically, it is certainly a nuisance to have the zoom ring move so easily. Of course, the degree of looseness varies from lens to lens. So, you will need to evaluate how bad it really is and weigh that against the price. This problem usually cannot be repaired cheaply, although it can be "fixed" using the the barrel tape trick.

This trick involves taping the barrel of the lens over which the zoom ring slides. You will probably have to apply a few layers of tape but be methodical about it - check the zoom ring's looseness after each application. Eventually, you should be able to get the zoom ring to slide smoothly, without any free play.

Damaged Zoom Action

In lenses that have taken a good knocking, the zoom action may be damaged. In such cases, the lens may not be able to achieve its full zoom range.

To check for damaged zoom action, simply twist the zoom ring back and forth. Make sure the lens is capable of achieving its full zoom range. If it cannot do so, then the zoom action is damaged. You should also check for rattling sounds or focus problems since the shock that damaged the zoom action could also affect the lens elements or focusing helicoid.

If you have an external flash unit, like the Nikon SB-800 AF Speedlight or the Canon Speedlite 580EX II, you can use it to read the exact focal length from the lens at any particular point in its zoom range. Just turn on your external flash and it will display the lens' current focal length. Twist the zoom action from one end to the other end and use the external flash's readings to verify the lens' zoom range.

You can still use a lens with a damaged zoom action, if that is all that is wrong with the lens. There should be nothing optically wrong with it. All you have to live with is the limited zoom range. Such lenses can be repaired but the repair cost and the hassle of sending the lens for repair may not be worth the discount you get. So, unless you are getting it at a real bargain, it would be best to avoid such damaged lens.

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