The term “tracking zoom” is used to describe a zoom lens that, once set-up, will maintain focus throughout the full zoom range of the lens.
Tracking zoom lenses are of great benefit to users. However, to get the best performance from your lens you must set it up correctly each time you use it on a new camera. If you only use the lens on a single camera then the set-up need only be performed once. However, it is recommended that you periodically check the set-up to make sure nothing has changed and best performance is maintained.
Setting-up your tracking zoom is a relatively simple procedure but absolutely vital to ensure the best performance from your zoom lens.
Step 1. With the Zoom Lens mounted on the camera, zoom to the narrow image and use the lens focus to bring the image into sharp focus.
Step 2. Now zoom to the wide image. The image is likely to be out of focus consequently you need to focus by adjusting the register or back-focus setting. This can be done by using the lens register setting (if provided) or the camera adjustment. By adjusting the register you will bring the image back into best focus.
Step 3. Repeat steps 1 & 2 several times until focus is maintained at either end of the zoom without having to refocus. You will now find that optimum image quality is maintained at any point within the zoom range.
Your Zoom Lens is now set for optimum performance. Please keep in mind that this set-up procedure should be carried out even if you are swapping the lens between cameras with the same standard lens mount. Tiny positional errors between the camera register and sensor position can be enough to stop your lens tracking correctly. For further information on tracking zoom lenses please visit http://www.resolveoptics.com/zoom-lenses/