Quote Originally Posted by Paul McSweeney


Quote Originally Posted by Kayaker72
  • Dis-engagable extenders. Why don't they make external extenders that, with a push of a button, can be engaged or dis-engaged similar to the internal extender on this lens? That way this feature could be used for all compatable lenses. Right now I am thinking size, looking at the back of the 200-400 picture, the unit housing the 1.4x extender appears a littlelonger than the actual 1.4x extender. This makes me think that, in addition to an extender swinging into and out of place, there may be some other moving elements to make this work.. But, of course, that is just uneducated speculation on my behalf.




They'd have to redesign the optics of the current 1.4x extender to make a disengagable version for the other tele lenses. Consider the current separate 1.4x has a protruding front element, so it couldn't swing out of the way. In the 200-400 however it could be the same optical design as the separate 1.4xbecause it is built into the lens, sothey can build the lens body to accomodate swinging the entire optical unit in/out of the light path.


Paul.
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I was thinking of a redesigned extender, essentially slicing off the portion of the 200-400L that is the built-in extender that can slide in an out of place, and making optional extenders that could be used on any compatible lens. But, as I sometimes do, I typed before I thought, and thinking about it more the biggest problem if Canon ever created a product like that (extenders that can be disengaged) is that if the lens isn't designed for this option, when the extender is disengaged it would essentially be an extension tube. So I am not expecting to see that product anytime soon. Another million dollar idea that isn't worth 2 cents.


Here is a link to the ISO 12233 charts comparing the Nikon 200-400 to the Canon 300mm f/2.8L both at 300 mm f/4:


http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=704&amp;Camera=614&amp;Sample=0&am p;FLI=2&amp;API=0&amp;LensComp=249&amp;CameraComp= 453&amp;SampleComp=0&amp;FLIComp=0&amp;APIComp=2


If the Canon is optically equivalent or better, I can see it as a very flexible lens for high end users. If it is optically less, but still very good, then hopefully the price is much lower and this may be a flexible lens for someone like....me.