Teleconverters?

Discussion in 'Photography Beginners' Forum' started by Markw, Dec 31, 2008.

  1. Markw

    Markw No longer a newbie, moving up!

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    I have the Nikon D90. I was looking to buy a teleconverter for it. Say I wanted to buy the Sigma 70-300mm lens for it instead of the Nikon 70-300mm. What teleconverter would I need? Would I need a Sigma with a Nikon mount or a Nikon teleconverter? What terms should I lok for to make sure the camera still autofocuses with the TC on it? This confuses me terribly. Any help and/or links would be greatly appreciated. Thanks in advance.

    Mark
     
  2. chrisburke

    chrisburke TPF Noob!

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    i'm thinking you've mixed up your deffination of what a teleconverter is.. its not for mounting other lens on your nikon body.. Its job is to enlarge the central part of an image obtained by the objective lens. For example a 2× teleconverter enlarges the central 12×18 mm part of an image to the size of 24×36 mm.

    but to let you know how to go about a sigma lens on a nikon body.. you order the one with the nikon mounts... sigma makes lens that will fit on nikons, canons etc.. you just get the one made for the nikon
     
  3. Markw

    Markw No longer a newbie, moving up!

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    I know all of this. What Im saying is, I know both sigma and Nikon make Teleconverters. If I have the Nikon body, but the Sigma lens, which brand would I use? Since the Sigma lens has a Nikon mount, I would need a Nikon Teleconverter, correct? Or do other brands make teleconverters that would fit both the Nikon lenses and bodies?

    Mark
     
  4. chris miss

    chris miss TPF Noob!

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    You might want to contact customer service at Sigma. I have the 70-300 lens for a Canon and was thinking of doing the same thing. They told me that the 70-300 lens isn't compatible with a teleconverter. Maybe someone else knows something different, but that's what they told me.
     
  5. davebmck

    davebmck TPF Noob!

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    You can buy a third party teleconverter for your Nikon, just get one with the mount for your camera. There have been many threads here on teleconverters. You should do a search and read these, because there are many issues with using teleconverters, such as losing autofocus and incompatibility with certain lenses.
     
  6. Dao

    Dao No longer a newbie, moving up!

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    If I am not mistaken, the 70-300mm lens from both Nikon and Sigma will not work with the TC.

    You need a lens that has a Max Aperture of F/2.8 or larger in order to use it. And in general, the 2x TC lose 2 stops of light and 1.4x TC will lose 1 stop.

    So a 70-200mm F/2.8 will work and it behave as a 140mm-400mm F/5.6 lens with a 2x TC
     
  7. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    there are several types of teleconverter on the market:

    1.4 teleconverter - increases focal length of the lens by 1.4times and reduces max aperture of the lens by one stop; thus can be used on an f4 lens - moving it to an f5.6 which is the AF limit on Canon cameras and is petty much a limit on Nikon as well (unless you buy the top range flagship camera bodies). Note that whilst Nikon has no AF limit after f5.6 accuracy and speed take a noticable hit especailly in less than very bright conditions.
    A 1.4TC generally will give you very little to no (when combined with pro end lenses) loss of image quality and is about the best TC for your money.

    1.7TC - nikon make one and it takes away 1.5stops of light and also reduces quality further than a 1.4TC. I have not used one myself (canon user only) but to all extents I belive its a good choice for combining with a good lens (probably limited to primes only and the very top range of zooms)

    2TC - doubles your focal lenght, but also robs you of 2 stop of light - so its f2.8 lenses only or else your onto manual focusing. It also gives you a very noticable drop in image quality. This TC is best reserved only for the top lenses where a drop in quality will not be too damaging on the final image.

    As for the lenses you are thinking of - the 70-300mm zooms - I don't think any TC would be of use on them - even the 1.4s. The quality of the 70-300mm is just not high enough (in general) to be able to take a TC and still produce acceptable results - though of course acceptable is a personal standard. Also I don'y think there are any TCs that will actually fit a 70-300mm - certainly my Canon and Sigma TCs will not fit my 70-300mm sigma. Further after seeing the TCs in action and also my experiences of my sigma lens I think and boost in focal length gained would be offset by a larger loss of quality - cropping from a 300mm shot without TC would probably produce a better or equal quality image as one taken with a 1.4 TC and zoomed in closer
     

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