Instruction: Using the product's title, description, features, price, and brand, identify and retrieve the values associated with a specified set of target attributes. Output the extracted values along with their respective sources (e.g., title or feature) indicating where each value was found.

Input:
Product title: Canon EF 35-70mm Macro Telephoto Lens for Eos Camera
Product description: This is the rare MARK I lens version, not the cheap plastic mount model. The particular lens is one of Canon's truly forgotten gems. The overall construction of this lens is simply amazing. Keep in mind this lens was last marketed in 1987, so it is no longer available at retail, thus becoming more difficult to find in this condition. Because of the 1.6X crop factor on the newer Digital Bodies such as the Rebel XT, 30D, 40D or any other Canon EOS bodies, the lens is equivalent to a 56-112mm zoom lens. Because of the extra zoom, this lens makes for an excellent portrait lens for all you photographers looking for a mid to wide zoom.
Product feature: Lens Construction (group) 8, Lens Construction (element) 9, No. of Diaphragm Blades 5, Minimum Aperture 29, Closest Focusing Distance (m) .39
Product brand: Canon
Target attributes: Fixed Focal Length
Answer: attribute: fixed focal length
value: None
source: None