First of all, be sure you are using the correct photo lingo when you use the word "fuzzy". Do you mean "camera motion"? Do you mean "out of focus"? Do you mean "the image was in focus and there was no camera motion, but the lens was of poor quality and did not have the ability to render a clear and distinct image onto the film"? Each of these definitions is a different meaning for the word "fuzzy", and each will appear differently on the film.
Did you ever shoot some test slides to check lens sharpness before heading out into the field to photograph moving trains? Set up your zoom on a tripod and shoot photos of stationary trains from the same distances that you would be using to photograph moving trains. Use a variety of focal lengths, and for each focal length use a variety of equivalent exposures so that you cover the entire range of f/stop and shutter speed combinations for your lens and camera (e.g. 1/60 @ f/16; 1/125 @ F/11; 1/250 @ F/8; 1/500 @ F/5.6, etc., depending on your film speed and lighting conditions). These are called equivalent exposures because you get the same exposure on the film even though the settings are different. Write down each f/stop-shutter speed-lens focal length combination for each photo for future reference. Take a look at your test slides to see if the lens is as sharp as you wanted at all focal lengths. If these photos are not sharp, take the lens back to the camera store for exchange or refund. You would be amazed at how much difference there is from lens to lens of the same type and manufacturer, and you might have gotten one whose lens elements are out of alignment. Even reputable lens makers produce a sub-standard lens now and then. If the lens was purchased in used condition, it might have gotten bumped very hard by its previous owner which could cause focus or lens alignment problems. Nearly all zoom lenses are trade-offs between their convenience and 1.)sharpness, 2.)maximum f/stop, 3.)weight. When buying zooms, spend as much as you can afford in order to get the sharpest lens possible. Send your child to college next year, get a second mortgage on your house, take on a second or third job. Just do whatever it takes to get the dough for good glass, especially with zooms. John B. Corns --> SPORRS: Serious Photographers of Railroad Related Subjects
