Which Teleconverter?

[confindelmundo]

<p>Hello Folks,</p>

<p>I have a Nikon 7000 and a Sigma lens for Nikon, 120-400 mm. If I want a teleconverter from Nikon 1,4x, which one should I buy?</p>

<p>Thank you.</p>

[Wouter Willemse]

<p>If I recall correctly, the Sigma-lens has a f/4.5-5.6 aperture. I wouldn't mount any teleconverter on a f/5.6 lens at all, as the resulting effective aperture would be too small for AF to work effectively on a D7000, and typically the image quality takes a (too) significant hit.<br>

Either way, it may be that the Nikon TC will not mount by default as Nikon added a tab on them to avoid using them on most lenses. A second consideration is the risk of the rear element of the lens to hit the protruding front element of the TC. You could check with Sigma for their teleconverters, but the limitation of the effective aperture will remain.</p>

[Matthew Brennan]

<p>I agree with Wouter, adding a TC to an f/5.6 telezoom will yield AF difficulty with all but the brightest lit / high contrasting subject matter.</p>

<p>However, if you are still keen <a href="http://www.sigmaphoto.com/teleconverter-compatibility">this compatibility chart</a> is found on the Sigma website. Alternately, as suggested you will in all likelyhood need to file the tab down on a Nikon TC.</p>

<p> </p>

[Peter_in_PA]

<p>You are probably better off cropping the non-TC image anyway.</p>

[confindelmundo]

<p>Many thanks for your answers which make sense. Fortunatelly I did not buy yet any converters. My lense is quite new, so I will keep taking pictures without converters meanwhile, and maybe crop. Greetings to all.</p>

[munim]

You're better off upgrading to D7100. The extra megapixels allow you to crop more and still maintain IQ. D7100

horizontal resolution is 6000 vs 4928 pixels for D7000. So that's worth about 1.2x increase in focal length.