Canon 2x extender

<p>I have a 300mm f4 lens. I regularly use a 1.4 extender with it. I would like to get more reach. In the past I did not consider the 2x extender, because it costs a two stop reduction in light. I recently upgraded to a 7D and the increase in ISO speed reduces the need for a wide open lens. Who has experience with a 300mm f4 and a 2X extender?.</p>

<p>A 300mm f/4 won't AF with a 2x on the 7D - you're at f/8 there.</p>

<p>Actually that might not be entirely true - it will probably work<em> to some extent</em> on the off-centre AF points - but how satisfactorily is in the lap of the gods.</p>

<p>That's a tough one. It will certainly be taking you to the edge in many different ways. Although I've never used the 2X on the 300f4 I have used a 1.4 on it. Also, I have a 300 2.8 and both a 1.4 and a 2X TC. Based on those experiences with a 7D I'll say this: You are going to have a lot of limitations and your results may be less than optimal. Low light will be forcing you to use very high ISO's. You will likely be using manual focus. Even when the light is good you will then be dealing with the hit you take on sharpness. Only you will know if the results will be satisfactory. I will say that I rarely use the 2X on the 300 2.8 which is one of the sharpest lenses out there because of the IQ degradation. In many cases I'd rather shoot the 300 or 300 + 1.4 and just not go with the 2X.<br>

Now... don't get me wrong... I'm not saying don't do it... I'm saying proceed with caution. I'd rent a 2X TC for a week and play with it to see if it is something you find satisfactory.<br>

Here is a compatibility chart:<br>

<a href="http://www.bhphotovideo.com/FrameWork/charts/canon2xExtender.html">http://www.bhphotovideo.com/FrameWork/charts/canon2xExtender.html</a><br>

Rent one from here:<br>

<a href="http://www.lensrentals.com/rent/canon/lenses/teleconverters">http://www.lensrentals.com/rent/canon/lenses/teleconverters</a><br>

Richard</p>

 

<p>As said above, I don't think it will AF at f/8 on the 7D. I've used it with a 500 f/4 on a 1D IV with satisfactory results. I like the 1.4x much better, but when compared, a full res 2x shot is a little better than a cropped shot with the 1.4x. That being said, I try to get close enough not to need the 2x and use it only as a last resort when I am very far away, but in good light it performs fairly well. Here is a shot with the 500 f/4 + 2x. It's hard to analyze sharpness from a resized photo, but you can get an idea. Also, I am referring to the Canon extenders. I haven't used others, but have heard some 3rd party 2x extenders are pretty terrible.</p><div></div>

This set up does not AF although the live view contrast AF should work.

 

Optically the 2X on this lens is OK based on tests with the 20D, i have not got around to retest with the 7D.

 

I do find with the 300/4 IS + 1.4x and 7D I can crop down to 1/4 frame by area to get reach as long as I keep the shutter

speed up, images print great at A4.

<p>I was never happy with the qualify of 300/4 IS + 2x. In my own tests, I couldn't tell the difference between using the 300 + 1.4 and then cropping vs using the 300 + 2x. Since I couldn't see a quality difference with the 2x, I decided the loss of autofocus wasn't justified.</p>

<p>I use a (Sigma) 2x on my Siggy 120-300mm f/2.8 OS much of the time, and on a lens designed to work well with a 2x, results are very good:</p>

<p>http://www.capture-the-moment.co.uk/tp/tfu29/upload/260912/house_sparrow_st_marys_3.jpg, handheld.</p>

<p>But as I've pointed out, <em>on paper</em> at least, the 7D will not AF at f/8.</p>

<p>You might get passable AF on the off-centre AF points (as I did<strong> <a href="http://www.capture-the-moment.co.uk/tp/tfu29/upload/Bridlington_September_2011/carrion_crow_bridlington_1a.jpg">here</a></strong> - this being my 100-400mm and a non-reporting Kenko 1.5x, handheld at 600mm) but it's very hit-and-miss, and while off-centre AF points at f/8 work for some, I've had people <em>insist </em>that I could not have used AF to get that shot...</p>

<p>Don't do it, you will regret it.</p>

<blockquote>

<p>I was never happy with the qualify of 300/4 IS + 2x.</p>

</blockquote>

<p>Neither was I. I tried it on film, with an EOS-3, and never obtained truly satisfactory results. I tried it on a 40D, using live view mode to focus. Again, never really happy with the outcome. The fixed focal length 400mm f5.6 L, together with the 1.4x, is a much happier combination.</p>

<p>What a great forum. Thank you everyone for your advice. You have saved me time and money. I appreciate it. </p>

I have the 1.4x II and 2x II. Ht rarely use the 2x even on a

body that will AF at F8 the AF speed is not very good. In

addition the IQ impact as others have mention is quite

noticable. I just concluded that I get better results cropping

the 1.4x than I do shooting with the 2x

<p><img src="http://www.meckstein.com/post/df.jpg" alt="" /></p>

<p>Canon 2x works very well. This taken with 400 ƒ5.6 and Canon 2x</p>

<p> </p>

Just to be clear there was a small measurable advantage with the 2x over the 1.4x plus crop on a 20D. As Eric indicated

the higher sampling rate of the 7D probably means no advantage over cropping although I have not done the SRF tests

to confirm.

<p>Talking more generally about the 7D with a 2x, I can give a confident assurance that - with the right lens - there surely is an advantage to using a TC over cropping.</p>

<p><strong><a href="http://www.capture-the-moment.co.uk/tp/tfu29/upload/260912/house_sparrow_st_marys_3.jpg">This</a></strong> is with my <strong>Sigma 120-300mm f/2.8 OS</strong> and <strong>Sigma 2x</strong> on my 7D, handheld at <strong>600mm, f/6.3, 1/320, 1000 ISO</strong>, near as dammit "full frame" - just a tiny bit off the RHS, to centralise the bird in the frame.</p>

<p>(Note that images are just about as sharp at f/5.6, but f/6.3 is a tad more consistent when shooting handheld at close range to the subject).</p>

<p>I'll take this image quality over cropping the lens + 1.4x, if for no other reason than that I can crop this quality of 600mm image very effectively for even more "reach". To be clear, this is as good as, or better than, cropping from 420mm (that obviously depends on<em> how much</em> cropping is involved), and as I say, I can then crop if needs be: this image is noticeably sharper/more detailed at higher resolution, but let's be honest, it's pretty good as is.</p>