Will a Canon extender work with a Tamron lens?

[Marvin]

<p>I'm enjoying the versatility of my 18-270mm Tamron lens on my 7D. Can I pair that up with a 1.4X Canon tele-extender?</p>

[JosvanEekelen]

<p>Probably not. The Canon extenders have a protruding front element that may interfere with the rear element of the lens. Apart from that an 18-270 lens is not a good starting point for an extender. You'll loose a lot of quality, probably autofocus as well.<br>

If you want to try an extender have a look at 3rd party options.</p>

[Michael R Freeman]

<blockquote>

<p><em>"I'm enjoying the versatility of my 18-270mm..."</em></p>

</blockquote>

<p>Even if you could pair the Tamron 18~270mm with a Canon 1.4X tele-extender, I have serious doubts that you would enjoy the combination. It won't autofocus, at f/9 maximum aperture on the telephoto end (where you'll use it) it will give a dim viewfinder image that will make accurate manual focusing challenging, and the need to stop down at least a couple of stops further to f/18 to marginally improve the compromised image quality means very slow shutter speeds in all but the brightest full sun unless you really jack up the ISO.</p>

<p>In short, this particular lens is just not a good candidate for any tele-extender, Canon or otherwise.</p>

[brian_wallace5]

<p>It will not work with the Canon 1.4x. <br>

A third-party extender (Tamron, Kenko) would mount and probably "work" depending on what you mean by work. Michael points out that the autofocus would be questionable at best.</p>

[Marcus Ian]

<p>Short answer is no. The rear element of the Tamron and the Canon TC's extended front element will clearly contact each in at least some points of the zoom range resulting in damage to both (if you can even mount the Tamron)<br>

All other concerns are moot. </p>

<p>... but, <em>if</em> you could safely mount the lens on the TC (and you can, using other TCs), then you wouldn't loose AF completely, since the lens wouldn't recognize (and report) the TC - plus, the lens 'lies' to the camera anyway to ensure the AF system is enabled... it <em>is</em> likely that you'd loose some AF functionality in low contrast, and poor lighting situations - but how much would largely be dependent upon FL, subject contrast, and lighting.<br>

As far as the loss in IQ goes, I guess that depends upon you, and what/how you shoot. Some photographers won't touch a piece of equipment which may result in a slightly diminished IQ, others would rather get a shot they'd otherwise miss completely. The 18-270 is certainly a 'compromise' lens to begin with though, and will only be made more so w/ the addition of a TC (of any brand) - whether or not that (sometimes significant) loss of IQ is important <em>to you</em> is up <em>to you</em>.</p>