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New lens or Extender

Discussion in 'Canon Conflab' started by medavidcook, Jul 21, 2015.

  1. medavidcook

    medavidcook Well-Known Member


    I have a 55-250mm lens and looking at maybe getting a 400 fixed or a 100-400mm zoom or should I just go for an extender as already have a 55-250mm lens.

  2. nimbus

    nimbus Well-Known Member

    Extenders or converters tend to work best on the upper end lenses. One problem with them on a wide range zoom is that the finder image becomes dark, in some cases the light loss also leads to autofocus becoming inoperative, the longer end of an f5.6 with a 2x converter loses two stops of light becoming in effect f11.
  3. PeteRob

    PeteRob Well-Known Member

    If the max aperture of the 55-250 at the long end is F5.6 then don't bother with an extender even if you have a camera body that will AF at F8 with the center spot. The canon extenders are good with lenses of F4 or faster.

    The two other options are a big step up in price. I have the 400 F5.6 L which is an excellent lens although you are a bit limited on shutter speeds because it has no IS. If you are always shooting things smaller than the field of view this is a good lens. If you want something you can take to the zoo get the zoom. It might be a bit heavier and less sharp wide open at the long end but it is much more flexible.

    I have used an extender on the 400. At F8 the loss of non-centre focussing points means no track focus so for wild-life in motion you have to be able to keep the one point exactly where you want it. On a long lens handheld this is almost impossible.
  4. El_Sid

    El_Sid Well-Known Member

    Point 1: Canon extenders don't work with EF-s lenses. They simply don't fit and even if they did they may automatically disable the AF on the camera - probably even one with f8 capability if the extender were a 2x type.

    Point 2: Third party teleconverters may fit but even then some are not compatible with EF-s lenses (my Teleplus models aren't). Third party converters are less likely to automatically disable the AF (they don't communicate the required effective aperture setting) but it's almost certain it won't find focus either. I have tried my converters on EF lenses with this kind of slow aperture and they simply thrash back and forth through the focus range without ever locking on.

    Point 3: Converters and extenders degrade image quality, the 1.4 x less than the 2, so are best suited to lenses with high image quality to begin with (primes, top end L zooms). The 55-250 is a good lens but even so I think the results with a converter, assuming you can focus it, would not be as good as you'd like.

    I'd honestly save the pennies for a proper long lens. With the new 100-400 MkII coming on the market there's a fair few MkIs starting to turn up on the used pages. By the time you've saved up the money there may a few bargains to be had...
  5. Roger Hicks

    Roger Hicks Well-Known Member

    Same here. Although the best zooms are a LOT better than they were, not all are the best, and even among the best, comparatively few perform at all well with anything except matched, manufacturers' converters -- and then they really are deadly slow.

    But then, what does the OP want to photograph?



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