Canon EF 28-105mm lens
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The Canon EF 28–105 mm f/4-5.6 is an inexpensive zoom lens often included as a kit lens with Canon 35 mm single-lens reflex cameras. 28–105 mm is a standard wide to telephoto zoom range. The Canon EF 28–105 mm f/3.5-4.5 USM is a higher quality zoom lens with a better build quality. Currently every version of this lens is discontinued. Some versions of the lens may include the word macro or a flower icon which indicates macro capability, however due to the 1:5.2 image magnification ratio it cannot be considered as a true macro lens.
EF 28-105mm f/3.5-4.5 USM 
This lens is a well-regarded consumer-grade lens. Its focus motor is ring USM, resulting in quick and quiet autofocus operation; this motor also allows the lens to offer full-time manual focusing. The lens uses internal focusing so the inner lens barrel does not rotate when focusing. This lens uses a "duo cam" type zoom barrel, this allows a more compact design, but still does not rotate while zooming.
This duo cam type zoom barrel is illustrated with the following two pictures:
There are three versions of this lens. The original lens has a five-blade diaphragm. The second version, with the flower icon having been replaced with the word "Macro," has a seven-blade aperture but no change to the name of the lens. The third version is named 28-105 3.5-4.5 II, and it has 7 blade diaphragm along with some minor physical changes.
EF 28-105mm f/4-5.6 USM 
These are two inexpensive versions of the 28-105mm, cosmetically similar to the EF-S 18-55mm or the 90-300mm lenses which have the characteristic rubber grip on the barrel. While retailing for around $100 less, these lenses have a decreased f-stop range and cheaper build quality (with a chrome-plated ring). The first 4-5.6 version has a DC motor for autofocus, while the second version uses a micro-USM, instead of ring USM that the 3.5-4.5 models use.
|Weight||0.46 lbs. / 210 g||0.83 lbs. / 372 g|
|Diameter||2.6" / 6.7 cm||2.8" / 7.2 cm|
|Length||2.7" / 6.8 cm||3" / 7.5 cm|
|Filter diameter||58 mm|
|Horizontal viewing angle||65° - 19° 20'|
|Diagonal viewing angle||75° - 23° 30'|
|# of diaphragm blades||6||5 or 7|
|Closest focusing distance||1.57'||1.6'|
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