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FORUMS ➔ Cameras, Lenses & Accessories ➔ Canon Lenses 
Thread started 22 Jan 2008 (Tuesday) 13:43
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OK Propeller heads, explain something for me...

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FlyingPete
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Jan 22, 2008 13:43 |  #1

I have a 70-200 f/2.8L, as we all know this is a constant aperture lens.

So my question is around the element size required for a given f-stop at a given focal length. From my understanding at 200mm to achieve f/2.8 you need a 71.4mm element. So why doesn't this same element allow f/1.02 at 70mm :confused:

I suspect this is something to do with the constant aperture design but still confused.

Peter Lowden.
EOS R6 and assorted glass

  
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OK Propeller heads, explain something for me...
FORUMS ➔ Cameras, Lenses & Accessories ➔ Canon Lenses 
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x 1600
y 1600

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