3.2 Variable Focal Length (Zoom Lenses).
Description
This article is from the Gross
Specimen Photography, by Ed Uthman, MD
3.2 Variable Focal Length (Zoom Lenses).
These are very convenient for general photography, since you don't have to move the camera so much. I am still waiting for someone to come up with an affordable zoom lens that is macro at all focal lengths and can focus on close objects. Many of the lenses advertised as "macro-zooms" are really just zoom lenses that allow close-up photography only at a fixed focal length. When in "zoom" mode, such lenses are not macro. Other zooms supposedly have "continuous close focusing" throughout their range of focal length, but the specs I have seen on these show that they all have a minimal focusing distance that is too long for practical use on a copy stand. My advice is too stay away from zooms unless you are really up on the capabilities of the individual models and know exactly what you need. If are absolutely set on using a zoom lens, you could try this: get a regular (non-macro) zoom lens which zooms by turning a ring rather than sliding a slide (i.e., a zoom lens which is not a "one-touch" zoom). Then put extension rings between the zoom lens and the camera. Extension rings are simply a set of tubes which extend the lens forward from the body of the camera. This will give you a zoom lens which focuses close-up but not far away. Extension rings can usually be had for less than $100. Appropriate zoom lens focal lengths would include 28 - 85mm and 35 - 105mm.
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