specifications:
Focal length: 50-300 mm f4.5 L
Aperture ratio: 1:4.5
Lens construction: 13 groups, 16 elements (including 2 UD glass elements)
Coating: S. S. C. (super spectra coating)
Angles of vlew: Diagonal 46°- 8° 15, Vertical 27° - 4° 35' Horizontal 40.- 6° 50' Focusing mechanism: Rotation of front lens group
Zooming: Two-ring rotary type, mechanical compensation system
Mimmum aperture: f/32. A
Closest Focusing Distance: 2.5 m (8 ft.)
Diaphragm: Automatic
Filter type: Rear section filter holder, drop in type (with 34 mm exclusive filter Regular 1X)
Cap: S-95 (CA2-3144)
Filter Size: acetate or gelatin w/filter holder GH Regular-L (CG0-2006)
Lenshood: Lens Hood S-100 (C44-8111)
Case: Exclusive (C48-0101)
Coating: S.S.C. (Super Spectra)
Function: Auto Aperture, Full aperture metering (AE operation when used with ALL Canon automatic SLR cameras.
Length x max. diameter: 250 mm x 104 mm
Weight: 1,820g.

This lens combines the advantages of a normal, portrait, telephoto and long telephoto focal lengths, and comes with a reasonable speed for its zoom range. Although in films or on television, lenses with zoom ratios of 10 or more are used to create impressive zoom effects. But an increase in the zoom ratio means loss of brightness and a deterioration of image quality. Therefore, the zoom ratio is usually limit to 2 or 3 with ordinary still photography lenses. The lens featured here, however, boast an unusually high zoom ratio of 6x and was also the first of its kind to use internal focusing. The 50-300mm f4.5 L was Canon\'s eventual answer to frequent requests from professional photographers to demand a similar class of high performance zoom lens, although this lens has long been available in Nikon\'s Nikkor line-up.

The FD 50-300mm f4.5 L lens was boosted with two UD glass to correct the secondary spectrum and thus achiveing high optical performance despite its high zoom ratio and with such a complex optical construction within.