With two lenses ranging in focal length from 24-300mm, I rarely found a need for shorter or longer focal lengths in most travel and people photography. (Left) at 24mm; (Below) at 200mm; both at f/11; B+W polarizer; Fujichrome New Provia 100F.)

A two part internal barrel (instead of a single fixed tube) helps keep this lens compact. Naturally, this internal barrel does extend when zooming to longer focal lengths, protruding by 2.8" at the 135mm end. The mount is made of stainless steel with gold-plated electronic contacts; the barrel is constructed of aluminum alloy with some polycarbonate components for durability. The designers also included a Zoom Lock mechanism that can be set at 24mm so the lens does not extend while you're carrying the camera around. The removable corner-cut (notched) lens hood is designed to shade the front element from stray light at all focal lengths without intruding on the image area. The optical formula includes a unique Anomalous Dispersion element. Tamron says this optimizes the dispersion characteristics of the optical system to compensate for lateral chromatic aberration at wide angle settings and helps compensate for chromatic aberration at longer focal lengths as well. Four Hybrid Aspherical elements help provide high image quality across the frame at short focal lengths. Made by bonding a non-spherical surface onto conventional glass, these are far less expensive to produce than ground and polished aspherical elements, but offer similar benefits. They correct distortion and spherical aberration (curvature of field) for more consistent edge-to-edge sharpness even at wide apertures, reduce comatic flare and linear distortion, and minimize size and weight as fewer elements are required.

Focus is internal but the focus ring does rotate during AF operation; I had to hold this short lens carefully so my fingers would not impede its movement. Both focus and zoom rings are coated with rubber for a good grip. A distance scale in feet and meters is provided but there's no depth of field scale, as with most rotary zooms today. I simply used the camera's depth of field preview to assess the range of sharp focus.

General Evaluation
During a week of extensive use in travel photography, I rated this Tamron zoom lens as an excellent performer overall.

It mated perfectly with an EOS-3 and all camera and flash functions operated perfectly. There was no looseness or "play" whatsoever. (The same applies to the 70-300mm zoom, too.) The notched lens hood worked well, but it's most effective at shorter focal lengths, like any hood on a wide to tele-zoom lens. In extreme sidelighting, I occasionally needed to change my shooting position slightly when flare was noticeable on the viewing screen.

Autofocus operation was reasonably quiet and focus acquisition was quick. The manual focus mechanism is also well damped, with enough friction for a familiar "feel." I really appreciated the Internal Focusing (IF) mechanism when using a polarizer to enrich blue skies or to remove glare from art deco buildings at South Beach in Miami. Because the front element does not rotate, the effect of the filter was not altered during focus (or zooming) operation.

A 70-300mm zoom is certainly more versatile than the more common 70-210mm models, while the extra focal length makes it more useful for some sports and for captive or habituated wildlife. Thanks to an element of LD glass, image quality can be high. (At 300mm; f/11; monopod; Fujichrome Provia 100F.)

Optical Evaluation
After viewing hundreds of slides under a 10x loupe, my final summary of this Tamron zoom's optical potential is that at the widest apertures, central sharpness is very high at all focal lengths. An 8x12 print would be highly acceptable unless the primary subject were near an edge of the frame. This is impressive performance for a zoom lens that ranges from a very short 24mm into the medium telephoto range.

At one stop down from maximum aperture, image sharpness and resolution are high across the entire frame at all focal lengths. I could make sharp 11x14 prints from any of my slides. Peak performance is reached at around f/11 in the 28-80mm range; adequate for a sharp 16x20 print, with crisp definition of details as well as fine clarity, contrast, and color rendition.

Some slight vignetting--darkening at the corners--is noticeable at the shortest focal lengths with subjects such as the sky, but disappears by f/5.6. This is common with zoom lenses, especially those of broad focal length range. There is little barrel or pincushion distortion: lines near the edges of the frame are rendered quite straight.

In extreme close focusing, optimum image quality was produced in the f/11 to f/16 range. These are exactly the apertures that I would typically use in such work, for the depth of field required to keep an entire subject sharply rendered.

Frankly, I'm convinced that this lens is suitable for professional applications and I would happily continue using it for my stock photography. An even wider aperture--perhaps f/2.8 at all focal lengths--would make it an ideal lens for photojournalism. However, the size, weight, and price would increase substantially, making the lens impractical for most photo enthusiasts. As denoted by the gold stripe and SP designation (for Super Performance) this is a lens of superior quality. Though not inexpensive, it rates high on the price/value scale and will help to maintain Tamron's already stellar reputation.

The extremely close focusing ability of the 70-300mm zoom will be greatly appreciated by those who enjoy occasional "macro" nature photography. The highest magnification of 0.5x (Above) is substantially more impressive than the 0.25x (Below) common with most tele-zooms. (At 300mm; f/16; mirror lockup; Photoflex reflector; Manfrotto tripod; Fujichrome Velvia.)

AF 70-300mm f/4-5.6LD Macro
Tamron has made a 70-300mm zoom for years, but this model is entirely new, with enhanced (internal) anti-flare precautions, lighter weight, and wider zoom and focus rings. It also has a nine bladed diaphragm, creating a circular aperture, so out of focus highlights are rendered as round and not octagonal. But there's a more significant advantage. This model focuses much closer: down to 37.4" in the special Macro mode in the 180-300mm range for a maximum magnification of 0.5x or 1/2 life size. In this respect, this zoom competes with some single focal length macro lenses. Standard close focusing is typical for a zoom of this type: 4.9' for a maximum magnification of just over 0.25x at 300mm.

This is a very light lens with metal lens mount and rubberized zoom and focus rings. It includes an element of LD (Low Dispersion) glass to reduce secondary chromatic aberration, the tendency for various wavelengths of light to focus at different distances. This element is useful at longer focal lengths, especially at wide apertures, for superior image sharpness, contrast, and color reproduction. Considering the low price of this zoom, its other characteristics are not surprising. The front element does rotate during focusing, though not when zooming. The focus mechanism is smooth but without much friction and it does rotate during AF operation. The internal barrel protrudes quite far out (a full 3.4") in Macro mode at 300mm, but it's made of lightweight polycarbonate so overall balance is not significantly affected.

Evaluation
Intended as an entry-level telephoto zoom, it produced slides of high sharpness, especially in the mid range of focal lengths and apertures. With an ISO 400 film there would be little need to shoot at the widest apertures, allowing the production of images that would make for beautiful 8x10 prints. Stop down to f/11 and even 11x14 prints would be sharp, particularly near the center of the frame. In extreme close focusing, the loss of light is less than one stop, in spite of the lens extension required. This makes for a reasonably bright viewing screen and shutter speeds that do not become significantly longer. Optimum results were produced in the f/11 to f/16 range. Since depth of field is extremely shallow at high magnification, these are the f/stops to use when you want to sharply render an entire three-dimensional subject such as a blossom or a butterfly. Although Tamron's single focal length macro lenses produce even higher image quality, this zoom would be great for those who only occasionally need extreme close focusing capabilities.

At more typical focusing distances, sharpness/contrast was very good from 70-200mm, especially at f/8 and f/11, where the slides are truly impressive and are suitable for an 11x14 print. At the longer focal lengths, central sharpness was high but edge sharpness did benefit from stopping down. I did not hesitate to shoot at 300mm at f/8 when filling the frame with colorful macaws at the Parrot Jungle in Miami. My slides would make for nice 8x12 prints.

Slight pincushion distortion (bowing inward of lines near the edges of the frame) was observed, especially at longer focal lengths. Unless you plan to use a tele-zoom lens for formal architectural photography--highly unlikely--this factor is irrelevant. Flare is well controlled. The bayonet-type lens hood (removable for reversed storage) is very effective. Autofocus speed with the EOS-3 was good, capable of tracking vehicles traveling along a Florida freeway on bright days. AF operation is certainly not silent but is comparable to that of many other affordable zooms.

In moderately close-focus work, the 70-300mm zoom produced fine image quality at most focal lengths and apertures. Since the subject is often near the center of the frame in such photography, there was no need to stop down for superior image quality. (At 250mm; f/8; fill flash; Fujichrome New Provia 100F.)

Advanced photographers who demand professional caliber sharpness, resolution, and clarity may prefer the "pro" SP AF 70-200mm f/2.8LD zoom, but as a first tele-zoom, the AF 70-300mm f/4-5.6LD Macro would be a more suitable choice. Far more portable, it also extends to longer focal lengths and allows for much closer focusing. It would be great for family outings, hikes, and vacation trips when you want to travel light. Finally, since Tamron lenses have a fine reputation for reliability, it should provide years of trouble-free picture taking. If the price, performance standards, and extreme close focusing ability suit your own demands, this Tamron lens would make for a suitable investment. For information contact Tamron USA Inc., 10 Austin Blvd., Commack, NY 11725; (631) 858-8400.

Technical Specifications

AF 70-300mm f/4-5.6LD Macro
Construction: 13 elements (one LD) in nine groups
Angle Of View: 34 to 8
Minimum Focus Distance: 59" normal; 37.4" in Macro
Maximum Reproduction Ratio: 1:2 in Macro at 300mm
Filter Size: 62mm
Dimensions (LxD): 4.6x9"
Weight: 15.3 oz
Accessories: Hood; vinyl case
AF Mounts: Canon, Minolta, Nikon (D), and Pentax

SP AF 24-135mm f/3.5-5.6AD [IF] Macro
Construction: 14 elements (one AD and four aspherical) in 10 groups
Angle Of View: 84 to 18
Minimum Focus Distance: 15.7"
Maximum Reproduction Ratio: 1:3.3 at 135mm
Filter Size: 72mm
Dimensions (LxD): 3.1x9.5"
Weight: 18.5 oz
Accessories: Hood; vinyl case
AF Mounts: Canon, Minolta, Nikon (D), and Pentax