Reader's Comments - Index of - Free

Lens
A teleconverter is a small lightweight intermediate optic that will increase the magnification of a lens,
while reducing its effective aperture. So a 2X teleconverter turns a 300/2.8 into a 600/5.6. A lot of times
new photographers ask me if they can save money by buying a teleconverter and sticking it onto their 28-
70 zoom to get a 140mm lens. Sadly, good teleconverters cost $400 or $500 and they only work
optically on expensive lenses. With a typical zoom lens, you'll get vignetting (darkening of the corners)
when using a teleconverter.
Teleconverters are for professionals who own expensive lenses and want to save weight by not carrying
two lenses. They are also useful sometimes with specialized tilt-shift lenses so that you don't have to buy
these in lots of different focal lengths.
Zoom lenses
Why carry around a whole bag of fixed focal length ("prime") lenses when you could just buy a Tamron
28-200 zoom lens for $300? With a twist of a ring, the Tamron will give you any focal length from
28mm to 200mm. The only problem with this idea is that, sadly, the laws of physics and common sense
have not been repealed.
Photographic lenses in general are not very good. They only appear to be good because people very
seldom enlarge or closely inspect images. Lenses are subject to many kinds of distortion, all of which
are more difficult to engineer around in a zoom lens. Furthermore, zoom lenses tend to be slower (admit
less light) than prime lenses. This forces the photographer into using flash and/or a tripod.
Does that mean you shouldn't buy a zoom lens? Absolutely not. I own three beautiful zoom lenses for
my Canon EOS system: 20-35/2.8L, 28-70/2.8L, and 70-200/2.8L. These are a great convenience for the
lazy and/or pressed-for-time photographer. However, none of these are as good as prime lenses in their
focal length range. Each of these zooms costs about $1500 so they won't help you out if you don't like
the prices of the prime lenses.
Personally I'd rather have my 28-70/2.8L than a 50/1.8. But I'd rather have the 50/1.8 than Canon's
cheaper mid-range zooms. And I'd rather have a Yashica T4 point-and-shoot than a bottom-priced
Tokina mid-range zoom.
Weird Lens #1: The Fisheye
See my review of the Canon 15mm fisheye lens.
Weird Lens #2: The Beyond 1:1 Macro lens
As far as I know, Canon is the only company in the world that makes a lens intended for convenient
photography of objects smaller than a 35mm frame. See the photo.net review of the Canon MP-E 65mm
http://www.photo.net/making-photographs/lens (6 of 9)7/3/2005 2:22:04 AM