On Jan 15, 2009, at 1:36 PM, Luiz Felipe wrote:
The problem here seems choice of words. You seem fed up with "crop factor" but willing to apply "field of view equivalence" to describe what happens when you change the size of the film or sensor used to capture the image.
I only use equivalence terms when discussing the subject of crop factor with users. I use neither of them when discussing lenses for a particular camera system.
Call it aardvark or pink panther, there is a numeric relation that will help me translate the lens to their new use. The same as my 120 and 4x5 experiences.
Do you call your 35mm camera lenses by a "crop factor" on your medium format and large format camera lenses? "Well, the crop factor for my Hasselblad 150mm lens makes it a 275mm lens for my Pentax K1000."
Just nonsense. It's a 150mm lens, the focal length has a meaning with respect to the FoV *in the context* of a particular format. Period. If you need to equivalence those fields of view, call the factor by which they difference an equivalence factor, not a crop.
Or just call it a telephoto lens for the 35mm camera and a portrait lens for the Hasselblad.
Or simply state the FoVs: 150mm = 21/21/29 degrees horizontal/vertical/ diagonal on the Hasselblad, or 13/9/16 degrees for the K1000. If that isn't informative enough, nothing is. It's a heck of a lot more informative than a "crop factor".
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