2x Teleconverter and autofocus

[girishmenon]

<p>I'm considering investing in a 400mm f/5.6 Canon lens for hand-held bird photography. However, I don't see myself using this lens more than 25 days in a year.<br>

Instead, I'm considering a Tamron SP 70-200mm F/2.8 Di LD [iF] for my D300 (yes, I use both Canon and Nikon gear). <br>

On their official website, they tell us that the Kenko TELEPLUS PRO 300 AF 2.0X DGX will autofocus with lenses having a maximum aperture of f/2.8. I'd like to know if you have any personal experience with using such a setup especially since I'd like to avail of all the focus points available on the camera.<br>

If this setup works seamlessly, the additional battery in the battery grip should help with the the speed of the autofocus, right?</p>

[rodeo_joe1]

<p>I've used a lot of teleconverters from Nikon, Teleplus, Vivitar and Telemore (Komura). Best by far is a 1.4x Nikon TC-14 converter, closely followed by the Vivitar 2x Macro converter - no longer made unfortunately. All other 2x converters I've tried, including Nikon's TC-201, aren't worth using IMO, and you're better off just cropping and digitally 'zooming'.</p>

<p>Issues range from a drop in contrast and definition to vignetting and very noticeable pincushion distortion. Metering accuracy is also affected in some cases. The Telemore converter ranks last FWIW, and is truly dreadful.</p>

<p>I currently have 3 AF compatible off-brand converters (probably out of the same factory as Kenko/Teleplus), which lie unused due to the above mentioned drop in IQ - make that 4 if you count the awful Nikon TC-16A.</p>

<p>The current version of Tamron's non-VC 70-200mm lens has a Built-In Motor (BIM) I believe, so autofocus speed won't be affected by the power source used for the camera.</p>

[oliver_flint]

<p>I haven't nearly the same experience as Rodeo Joe with TCs but have recently been using the new Nikon 2x TCIII with the Nikkor 300 mm f/2.8 for bird photography. The attached image shows that this combination can be quite sharp. Following Rodeo Joe's suggestion I imagine the TCIII 1.4x is even sharper.</p><div></div>

[georges_pelpel]

<p>Another example with the Nikon TC-20eIII.<br>

Shot this afternoon in Alsace, France.<br>

D810 + Nikon AF-S 70-200 f/4 VR + Nikon TC-20eIII, AF on light Gitzo series 1 tripod (from my travel kit).<br>

No sharpening.</p>

<p>Original image:<br>

<img src="http://logisoftinc.com/photos/2014/_GP12001.jpg" alt="" /></p>

<p>Crop:<br>

<img src="http://logisoftinc.com/photos/2014/_GP12001-1.jpg" alt="" /> </p>

[girishmenon]

<p><img src="http://www.girishmenon.com/forphotonet/BH01-13.jpg" alt="" width="700" height="467" /><br>

I have used the Nikon TC-14B on the Nikon 500mm f/4 P IF ED AiS lens with excellent results. I was considering the Nikon TC-301S but then again, I can do more with an AF teleconverter, like use it on a 70-200mm f/2.8 Tamron lens.<br>

Having gone to these sanctuaries a couple of times, I feel that I need that little more to make the sort of photos that I'm aiming for. Maybe I'll get the Nikon 1.7x instead.</p>

[glen_h]

<p>I have a Kenko 2X for Nikon mount. Seems that it was designed such that autofocus using the camera motor is geared down by a factor of two. The 2X converter also mutliplies the effect of focus changes, so the focus servo system might not be stable at 2X. (In addition to the aperture loss.)<br>

With motor in the lens, though, it isn't, at least on lenses that I know, reduced by 2X. <br>

In my tests, though, VR seems to work just fine. <br>

I don't know about TC vs. digital cropping. </p>