Steve'sDigicams

Contriver · Aug 6, 2006, 9:24 PM

I am considering purchasing a low-end DSLR as my next camera purchase, but I don't know anything about lenses. Does anyone know ofa website which has abeginner's guides to lenses?

Oneexample of something that confuses me is: One DSLR I am looking at is a refurbished Digital Rebel which comes with a Canon EF-S 18-55mm, f3.5-5.6 zoom lens. Why does it say f3.5-5.6? Why such a small range? Also, I figure since this lens is only a 55mm, I might need a telephoto lens as well. I found this on Amazon for $199: "Canon EF 80-200mm f/4.5-5.6 II Telephoto Zoom Lens". Again, why such a small f-number range? Are there 80-200mm lenses which offer a greater range? Is there some technicalhangup that prevents a lens from having a better range?

jacks · Aug 7, 2006, 1:45 AM

The f-stop numbers are the widest apertures, not a range of possible apertures. 18-55f3.5-5.6 means the lens can do f3.5 at 18mm but only f5.6 at 55mm. At any focal length it can be stopped down to much higher f-stop numbers.

Wildman · Aug 7, 2006, 10:21 AM

Get your hands on Canon's EF Lens Work III. It's really a big advertisement, but covers everything you'd ever want to know about fields of view, f-stops, etc. as well as manufacturing processes. Each lens in Canon's lineup (at publishing time) is covered specifically, complete with some beautiful photos. While the lens write-ups are Canon specific, most of the information is pretty generic.

You might find the book in a large library. I got my copy free of charge when I bought my EOS 20D from Canoga Camera.

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Aug 6, 2006, 9:24 PM	#1
Contriver Senior Member Join Date: Aug 2006 Posts: 268	I am considering purchasing a low-end DSLR as my next camera purchase, but I don't know anything about lenses. Does anyone know ofa website which has abeginner's guides to lenses? Oneexample of something that confuses me is: One DSLR I am looking at is a refurbished Digital Rebel which comes with a Canon EF-S 18-55mm, f3.5-5.6 zoom lens. Why does it say f3.5-5.6? Why such a small range? Also, I figure since this lens is only a 55mm, I might need a telephoto lens as well. I found this on Amazon for $199: "Canon EF 80-200mm f/4.5-5.6 II Telephoto Zoom Lens". Again, why such a small f-number range? Are there 80-200mm lenses which offer a greater range? Is there some technicalhangup that prevents a lens from having a better range?

Aug 7, 2006, 1:45 AM	#2
jacks Senior Member Join Date: May 2005 Posts: 221	The f-stop numbers are the widest apertures, not a range of possible apertures. 18-55f3.5-5.6 means the lens can do f3.5 at 18mm but only f5.6 at 55mm. At any focal length it can be stopped down to much higher f-stop numbers.

Aug 7, 2006, 10:21 AM	#3
Wildman Senior Member Join Date: Oct 2002 Posts: 544	Get your hands on Canon's EF Lens Work III. It's really a big advertisement, but covers everything you'd ever want to know about fields of view, f-stops, etc. as well as manufacturing processes. Each lens in Canon's lineup (at publishing time) is covered specifically, complete with some beautiful photos. While the lens write-ups are Canon specific, most of the information is pretty generic. You might find the book in a large library. I got my copy free of charge when I bought my EOS 20D from Canoga Camera.