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Thread: How big is f/1?

  1. #21
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    Quote Originally Posted by sehsuan
    the EF 50mm f/1.0L should have a filter size of 77mm if i remember correctly.
    i believe it's 72mm.

  2. #22
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    And talking about strange designs: Canon's 24-70/2.8L at the short (24mm) end is about 200mm long - not counting the hood.

  3. #23
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    i remember i read somewhere dat focal length divided by the aperture will give u the size.something like 200mm / 2.8 = 71.42mm,i might be wrong

  4. #24
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    Quote Originally Posted by blurblock
    200-400mm at f/2.8? Is there such a lens? at 400mm the aperture size of the lens will be around 142mm ..... adding another 54% for the angle of view, the filter size will be around 220mm
    Oops.... my bad... sehsuan has pointed out my mistake. Yah.... still it looks like a flower pot to me.

  5. #25
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    F-number is the ratio of diameter to focal length, technically speaking. But the definition only works for a simple convex lens, like the kind you draw in secondary school physics - 1 element only.

    The focal length of a real life lens is determined by the angle of view at the sensor/film - ie, despite how it looks or measures, if the angle of view landing at the focus point is a 50mm viewpoint, then that lens is classified as a 50mm lens. (That's why a physical 200mm 24-70 is a '24mm' at the wide end.)

    Can read more about it in Canon's Lens Work, at the back of the book. It gives a lot of technical definitions - F-number, focal length, etc.

  6. #26
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    my old PE teacher who is a photo enthuiast has one.. man.. compared to another fren's F1.8, ythe 50mm one is HUGE . No kidding.

    Sighz.. he have all the dream lens too... sighz... good thing is he lets me play with them sometimes.. very nice guy

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