Not necessarily, I actually look at it a bit differently. It really just depends on your requirements - If you want to shoot every image at the maximum available resolution, absolutely you need a zoon. However, if you want to scan all images (regardless of size) at a constant resolution then a prime may work just fine. For example, I normally scan pages 11x14 and smaller, and seldom scan anything larger than that. I normally scan at 300 dpi, so at 11x14 that translates to about 3300x4200, which puts me right at the 15 megapixel range to accomplish that resolution.Misty wrote: Even given the quality advantages a prime lens's optics have that you bring up, Jon, I'm thinking that a zoom lens might be better at dealing with that kind of size variation in my specific case; however, prime lenses might have an advantage for people dealing with mostly similarly-sized items.
Now assuming that I scan something smaller such as a 4x6 page, I would still normally scan it at 300 DPI. Zooming in with the full resolution available on the camera would increase the DPI because you are applying the same amount of pixels to a smaller area, so using the previously calculated 3300x4200 that would translate to over 800 DPI. I don't increase resolution for smaller pages, so for me it makes sense to scan smaller documents the same exact way I would for the larger size and just crop the image, pretty much the same as with a flatbed type scanner but in post processing. As such, this should be good for any size page up to the max size I have configured the setup for.
Now if I needed to scan something larger than my configured size or needed a higher resolution for a smaller page then that is really where a zoom may come in handy, just not for my application where I want to maintain a constant archival standard of 300 DPI regardless of page size.