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Why The EF 200-400 f/4L IS 1.4x Delay?

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neuroanatomist:
You're right, of course, Trowski.  I never even looked at the shorter supertele lenses that closely - my 600 II has sufficient space.  I suppose people are grasping at straws because this is one more delay in a long line of delays from Canon...


--- Quote from: sanj on November 16, 2012, 03:23:48 AM ---And if I had to put a filter on these lenses it would be almost certainly a grad and that would go in the front.

--- End quote ---

You'd need a pretty big grad filter (minimum front element size is 100mm diameter, filter would need to be even bigger) to put in front of a supertele lens, and some jury-rigged way to hold it there since there are no filter threads in front. 

sanj:

--- Quote from: neuroanatomist on November 16, 2012, 06:24:03 AM ---You're right, of course, Trowski.  I never even looked at the shorter supertele lenses that closely - my 600 II has sufficient space.  I suppose people are grasping at straws because this is one more delay in a long line of delays from Canon...


--- Quote from: sanj on November 16, 2012, 03:23:48 AM ---And if I had to put a filter on these lenses it would be almost certainly a grad and that would go in the front.

--- End quote ---

You'd need a pretty big grad filter (minimum front element size is 100mm diameter, filter would need to be even bigger) to put in front of a supertele lens, and some jury-rigged way to hold it there since there are no filter threads in front.

--- End quote ---

You suppose the 200-400 has front element that large?

neuroanatomist:

--- Quote from: sanj on November 16, 2012, 07:43:36 AM ---You suppose the 200-400 has front element that large?

--- End quote ---

Yes.  With a telephoto lens design, the entrance pupil is basically at the front element, and since the entrance pupil is the optical representation of the physical aperture (iris diaphragm) it has the same diameter.  400mm f/4 means a 100mm diameter entrance pupil (400 / 4 = 100).  With it being a zoom lens, the front element may need to be a little larger than that, to reduce vignetting.  If you compare it to the 500/4 II (~125mm diameter front element), you can see that it's probably at least 100mm in diameter:

sanj:
Thank you Neuro. I understand corrected.

Kit.:

--- Quote from: neuroanatomist on November 16, 2012, 06:24:03 AM ---
--- Quote from: sanj on November 16, 2012, 03:23:48 AM ---And if I had to put a filter on these lenses it would be almost certainly a grad and that would go in the front.
--- End quote ---
You'd need a pretty big grad filter (minimum front element size is 100mm diameter, filter would need to be even bigger) to put in front of a supertele lens,
--- End quote ---
http://www.cokin.co.uk/pages/cokinX.htm


--- Quote from: neuroanatomist on November 16, 2012, 06:24:03 AM ---and some jury-rigged way to hold it there since there are no filter threads in front.
--- End quote ---
There is a lens hood mount.

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