A&P Focal lengths with Film SLR vs DSLR

Discussion in 'Lifestyle' started by Claydus, Apr 13, 2006.

  1. Claydus

    Claydus Active Member

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    Ok so I have D70 and I was browsing fredmiranda.com reviews about a 20mm lense and someone mention if the lense was used with a DSLR the focal length would only be 30mm? What's the deal? :wtf:

    So that's what a 1.5 focal length multipler does to your pics??
     
  2. tenplanescrashing

    tenplanescrashing Active Member

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    its what they refer to as a 35mm equivalent. most DSLR's aren't full frame, hence the 1.5x crop. Nikons have the 1.5, canons have the 1.6. but there are a few full frame cameras (canon 5d is one of them).
     
  3. Jcolman

    Jcolman OT Supporter

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    it's not a multipler is a matter of physics. A DSLR uses a smaller size "negative" (sensor chips) than a 35mm SLR. The smaller size means that the coverage of a given lens is smaller than on an SLR. Conversely, a telephoto lens for a 35mm SLR will give you a longer lens on a DSLR.
     
  4. mojito

    mojito New Member

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    if you go into a dark room, and then shine a light through a lens and you look through the back of it (from a distance) you'll see the "circle of illumination" that the lens produces. So if you take this and what jcoleman said, you have that crop factor in a nutshell. thats why medium and large format lenses are so much more expensive, they have to produce a much larger image circle. and thats why ef-s lenses are so cheep, their circle is so small.
     
  5. Kinks

    Kinks Sup. OT Supporter

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    Technically, it's a Field of View crop, not a change in focal length... the focal length is a constant optical property, but the perceived field of view (due to a smaller sensor) means that 35mm on a DSLR "looks like" a 50mm shot on a film camera :)
     
  6. 00soul

    00soul halfsharkalligatorhalfman

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    :werd: focal length stays the same, you just see less in the viewfinder
     

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