The new Tamron AF55-200mm ƒ/4-5.6 Di II LD Macro zoom is an excellent choice for a hiker in a "tele" mood. It provides a focal-length range equivalent to about 82.5-300mm on a 35mm camera when used on the APS-C-sensor D-SLRs for which it was designed, yet weighs just 10.4 ounces.
The "Di II" in the name indicates that this lens is part of Tamron’s Digitally integrated II series of lenses that are optimized specifically for digital SLR cameras with APS-C-sized image sensors. These include all Fujifilm, Konica Minolta and Nikon D-SLRs (1.5x magnification factor) and the Canon EOS Digital Rebel XT and EOS 10D/20D/30D (1.6x factor). The smaller image circle used for the smaller APS-C-sized sensors allows for more efficient, smaller and less costly lenses, but will result in vignetting if such a lens is used on 35mm SLRs or full-frame D-SLRs.
I found the 55-200mm Di II zoom useful for a wide range of hiking subjects, including landscapes, detail shots, birds, beasties and flowers. It also worked well for aerial landscapes from lightplanes. I usually use lenses with built-in image stabilizers, so I was concerned about handholding the longer focal lengths without that assistance, but I found the Tamron zoom fit my hands well and presented no problems. I even got some sharp handheld shots at a shutter speed of 1/15 sec. at 144mm on the D-SLR I was using (that's equivalent to a 187mm focal length on a 35mm camera).
The mathematically minded among you will say, "Hey, 187mm is just 1.3x 144mm, not 1.5x or 1.6x 144mm." You're right; I tried the lens on a D-SLR with a larger-than-APS-C image sensor and a 1.3x magnification factor just to see how much vignetting would occur. The answer: not a lot, and easily cropped out. I'd stick with the cameras for which the lens was designed, though.
One of the 55-200mm zoom's best assets is its minimum focusing distance of just 37.4 inches at all focal lengths for a maximum magnification of 1:3.5 (the framing equivalent of 1:2.3 magnification with a 35mm camera). Other features include a nine-blade diaphragm for natural-appearing blurred backgrounds, internal surface coating to reduce ghosting and flare from the shiny digital image sensors, an LD (low-dispersion) glass element to minimize on-axis and lateral chromatic aberrations and, of course, the optical design that's optimized for the smaller-sized image sensors, reducing peripheral light falloff and maximizing sharpness across the image. List Price: $281.
Contact: Tamron, (631) 858-8400, www.tamron.com.
1 Optimized for APS-C-sensor digital SLRs
2 Compact portrait, sports and wildlife zoom
3 Focusing to 37.4 inches at all focal lengths
Specs Of Note
Focal Length: 55-200mm
35mm Equivalent: Approx. 82.5-300mm
Maximum ƒ-Stop: ƒ/4-5.6
Minimum Focus: 37.4 inches
Filter Size: 52mm
Size: 2.8x3.3 inches
Weight: 10.4 ounces
Mounts: Canon, Konica Minolta-D, Nikon-D