Tamron’s AF18-200mm F/3.5-6.3 XR Di II Lens;
By Joe Farace • November, 2005
Tamron’s
AF18-200mm F/3.5-6.3 lens is part of their digitally integrated (Di II) lens
series that’s designed for digital SLRs and is not recommended for use
with cameras having image sensors larger than 24x16mm, or 35mm film cameras.
The lens is available in Canon EF, Konica Minolta AF-D, Nikon AF-D, and Pentax
AF mounts and is maximized for smaller-sized imaging chips.
The lens is compact, smaller than you might think, because the use of extra
refractive index optics permit a smaller lens diameter while maintaining the
same aperture values as similar lenses. An internal focusing system provides
improved optical characteristics by minimizing light loss in the corners and
suppresses focusing aberrations, but my favorite feature is the AF18-200mm F/3.5-6.3’s
short minimum focus distance (17.7”) that at 200mm permits macro-like
capture. Low Dispersion (LD) glass elements compensate for chromatic aberrations
that can create problems at the telephoto end of the 18-200mm range.
Out Here In The Real World
I didn’t photograph any lens resolution charts with Tamron’s
AF18-200mm F/3.5-6.3 lens and I’ll bet you won’t either. Instead
I attached the lens (see “Canon Mount”) on two different Canon EOS
digital SLRs and captured images with a wide range of subject matter under many
kinds of lighting and environmental conditions. Through it all, I never encountered
any kind of mechanical or optical flaw in the lens that prevented me from capturing
the image I wanted. While photographing drag races with two different Canon
digital SLRs with the Tamron mounted on one and a Canon EF zoom on the other,
I was struck by how much faster the AF18-200mm F/3.5-6.3 lens focused than the
Canon lens. Because of the AF18-200mm F/3.5-6.3’s internal focus mechanism,
manual focusing with the lens was fast and crisp, too, but I rarely used it
that way.
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This photograph of a classic Ford Thunderbird was made at The
Mathews Collection (www.mathewscollection.com). Yup, there are
two other classic T-birds parked right behind it. I attached Tamron’s
AF18-200mm F/3.5-6.3 lens to a Canon EOS 20D that was solidly
mounted on a Manfrotto tripod. Exposure in Aperture Preferred
mode at ISO 400 was 3.2 seconds at f/40 to maximize depth of field.
After reviewing the histogram of a few test exposures, exposure
compensation was set at +1/3 stop.
All Photos © 2005, Joe Farace, All Rights Reserved
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“Without” moving the tripod from the original shot
of the Thunderbird, I zoomed the Tamron AF18-200mm F/3.5-6.3 lens
to 18mm to demonstrate its wide 11.1:1 zoom ratio. This exposure
was 1.3 seconds at f/22 in Aperture Preferred mode at ISO 400.
A +1/3 stop exposure compensation was used. Now, the Thunderbird,
which previously filled the frame, is seen as a small car parked
in the middle of a much larger collection that features several
rare McLaren automobiles in the foreground.
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The build quality of the lens is appropriate for its price point and maybe
just a touch better than you might expect and its compact size makes you want
to keep it on your camera all day. By using an image circle designed to match
that of smaller-sized imaging chips, Tamron produced a lens as compact as its
28-300mm lens, and, depending on your camera’s multiplication factor,
offers the same angles of view.
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Venues with interesting architecture and landscaping, such as
the Arvada Center for the Arts and Humanities, make interesting
infrared photography subjects. I mounted the Tamron AF18-200mm
F/3.5-6.3 lens onto a Canon EOS D30 that was modified (www.irdigital.net)
to capture infrared images. The lens was set at 18mm, but since
Tamron’s 18-200mm lens is designed for digital cameras with
smaller-sized imagers, the D30’s 1.6x multiplication factor
produced a focal length equivalent of 29mm. Exposure was 1/100
sec at f/16 in Aperture Preferred mode at ISO 400. A +1/3 stop
exposure compensation was used to open up the “white”
tree leaves.
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A “tulip” lens hood is included with the lens and did an effective
job of controlling flare at the 18mm focal length except in those extreme cases
where the sun was shining directly into the lens. Even then, flare was well
controlled and while present (I always like to use flare as a compositional
element) never significantly reduced the overall contrast of the shot. Sharpness
was very good at all focal lengths and with many different kinds of subject
matter, varying from portraits to landscapes to digital infrared architectural
images. I used the lens to photograph everything from close-ups to flowers to
tire-smoking dragsters and never felt like I wanted anything more.
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Dramatic drag racing images are possible with Tamron’s AF18-200mm
F/3.5-6.3 lens even from the grandstands. For this shot, the lens
was attached to a Canon EOS 20D and panned to follow the action
of this funny car. Exposure was 1/80 sec at f/18 in Aperture Preferred
mode at ISO 200.
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Backlit infrared? There are all kinds of so-called “rules”
about “when” you can capture infrared images, but
I’ve found that the best way to learn is to make pictures
and observe the results on the digital camera’s preview
screen. Sometimes you’ll be surprised as I was with this
backlit shot of trees made at the Arvada Center for the Arts and
Humanities. I used a modified Canon EOS D30 with the Tamron AF18-200mm
F/3.5-6.3 lens set at 22mm. Exposure was 1/200 sec at f/10 at
ISO 400.
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All of the pundits will tell you that you should only make infrared
photographs in bright sunlight, but I photographed this nearby
farm when a storm was approaching. The brooding effect of the
storm clouds, combined with the typical infrared effects on the
trees, produced an infrared image I thought was anything but normal.
Camera was a modified Canon EOS D30 with the Tamron AF18-200mm
F/3.5-6.3 lens at 200mm. Exposure was 1/200 sec at f/10 at ISO
800.
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