teleconverter for 70-300 1:4-5.6 is usm

Discussion in 'Canon EOS' started by dave_dise|1, Dec 1, 2009.

  1. I hike alot with my camera equipment. I chose the 70-300 as my telephoto for hiking. I am investigating adding a teleconverter to the hiking gear.
    I carry a wide angle for the landscapes and the telephoto for birds and other wildlife as well as far away objects like old mine remains etc.
    From many other postings I decided to look at the 1.4x not the 2x. I am not a practiced manual focuser and would find that a real problem. I can live with some reduced quality for the few shots for which I would use the TC.
    Any insight would be greatly appreciated. Since Canon does not make a TC for this lens, any 3rd party TC's you think I might want to consider for my needs would also be greatly appreciated (Tamron, Sigma, ...)
  2. As far as autofocus goes, with a 70-300 the difference between 1.4x and 2x is academic - AF will be gone or unreliable with either one. But you'll probably be happier with the 1.4x image quality and ease of manual focus.
    The TCs from Tamron, Sigma, and Kenko are generally considered pretty good. Some useful links - (review has samples with Tamron 1.4x)
  3. fjp


    I own a 70-300 IS and also have a Sigma 1.4X TC.
    You can mount the Sigma 1.4X TC on the 70-300, but you have to be very carefull:
    From 70mm to around 130mm the 70-300's rear glass element touches the converter front plastic protection and you always
    have to remember not to turn the zoom ring to the lower end.
    In practice that isn't a big problem because you only need a TC to get more reach and are only going to use it at the long range, to get 300-420mm focal lengths.
    Regarding autofocus, this converter provides autofocus over the entire range (the converter simulates a max 5.6 apperture), but at the long range (more than 200mm) it isn't accurate and tends to hunt a lot except with lots of light.
    In conclusion: it works but I wouldn't recommend it.
  4. My personal opinion is a SHARP 300mm photo enlarged is better than a 420mm poor quality shot. I would like to hear other opinions.
    Unless your 300mm zoom is very very sharp, I would not put a 1.4 tc on it.
  5. Forget about teleconverters completely unless you're shooting with L series primes. That's my blunt but experienced opinion. Crop your images instead. You'll save money, you'll save weight and you'll retain autofocus.
  6. Alan, Fernando, Ronald, Bob, and Jamie - thank you very much for taking time to share your experiences with TCs.
    Does the Tamron easily mount or are there tricks needed?
    Does the Tamron significantly degrade auto focus or is there a trick to tell the 50d to focus with the Tamrom mounted?
    When mounted does the Tamron hit the lens glass when the zoom ring is not extened as Fernando experieced with the Sigma?
    Again, thanks to all for the help - Dave
  7. Sometimes I use 7-300 IS with kenko 1,4 DG Pro 300 and it works beautifuly. It even autofocus at 300 ( 420) with the central point on a 20D. And at f8 ( which is f 11 in reality) it manages to be very sharp. The level of details you got in a long distance shot is much more than any possible crop you may try. The cheapest way to have the equivalent of a good 670 mm.

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