Auto focus using 2x extender plus 500 f4

[howard_jameson1]

<p>I switched slowly from EOS3 bodies to 40D and was surprised that the 40d is apparently software locked out for autofocus use with 500mm F4 L lens and the 2x extender which is my most used lens. The 1.4 ext works well. Want to know if the 60D, 7D or 5d mark II can be used on autofocus with 500mm and 2x extender. I shoot almost exclusively birds and manual focus is often to slow.<br>

Thanks, Howard</p><div></div>

[charedan]

<p>Only the 1D series were built to be able to AF over f/5.6. That is until the 1DX which does not. There is a trick were you can put tape over the 1.4 and 2X pins so that the camera does not know your past f/5.6 but of course the AF struggles. Canon choose not to have their camera's AF misbehave and prevented it for all other camera in firmware. </p>

[bobatkins]

<p>As above. Only the 1D series will AF at f8. The new EOS-1D X doesn't because (according to Canon) they had the choice of better AF at f5.6 and faster OR AF at f8 and their marketing research indicated that most professionals who use the top of the line EOS-1 series cameras would rather have better AF with f5.6 lenses. The fraction of users using a 2x with 500/4 and 600/4 lenses on a regular basis is apparently pretty small compared with all the users of their other professional lenses which are f2.8 and faster.</p>

<p>AF sensors capable of reliably responding to f8 have a physically different design. It's not just a software switch they can throw.</p>

<p>If you want AF at f8 with an EOS DSLR and don't want to break the bank, you should look for an older EOS 1 DSLR, maybe something like the 1Ds MkII which has 16MP, full frame and can be found for between $1500 and $2000. B&H have a used one right now for $2000.</p>

<p>You can try to get around the f5.6 limitation and tape up contacts or use a 3rd party 2x TC which doesn't communicate aperture change through to the camera, but it AF will probably fail just at the moment when you need it most!</p>

 

[nathangardner]

Only 1D will AF at f/8, an then it's center point only. The 1DX will not AF at f/8 however.

[lester_wareham]

+1

 

If the subject is static and you are resting the rig on something you could probably use live view contrast focus, bit of an

emergency facility though.

 

Not sure if the 40D had live view, may only be 50D on...

[robin_sibson1]

<p>40D had Live View but no contrast-detect AF. 50D, 60D and 7D, 5DII and 5DIII have Live View with contrast detect AF.</p>

[Marcus Ian]

<p>... if the subject is completely static... Even marginal movement totally eliminates that as an option. Given what the OP is shooting, I doubt that'd help him much.</p>

<p>IMPE (limited as it is) taping the pins works just fine, even though in marginal lighting you may have some trouble, in bright daylight though, your AF will probably work just fine.</p>

[howard_jameson1]

<p>First, let me say thanks for the very detailed and informed responses, plus the good suggestion on the older D1. I find it interesting that my old EOS-3 film units could auto focus with the 2x and the 500, but if the truth be told, it was often slow and if the background was complex, often couldn't find the subject even when the center focus point was on the bird.<br>

Again, thanks for info.<br>

Howard</p><div></div>

[scott_ferris]

<p>You can get a third party TC that doesn't report the focal length change and subsequent aperture loss. The Tamron Pro series is well rated and will AF a 500 f4.</p>

<p>Third party TC's are generally good on crop bodies.</p>

[howard_jameson1]

<p>Bob Atkins response got me all excited so started looking at 1ds mark II and mark III and if I understand it correctly, both will auto at F8; mark II is 16 meg and mark III is 21 meg.<br>

Am I correct that both will auto at F8. Next problem is finding them. Any ideas. B&H has some Mark III and found a couple on photo.net but one noted that he had the shutter replaced which he said was a common problem. Any inputs on this.</p>

<p>Thanks, Howard</p><div></div>

[scott_ferris]

The 1D MkI, MkII, MkIII & MkIV and the 1Ds MkI, MkII and MkIII all AF at f8.

 

For birding I would expect he 1D MkIV to be the best buy. For high resolution the 1Ds MkIII is best and if you can live with

the frame rate gives the same pixel density of the crop camera 1D MkIII.

[howard_jameson1]

<p>Scott, thanks for the input. Looks like I need to find a good used 1Ds MkIII.<br>

Again, thanks everyone for the good info and quick response.<br>

Howard</p><div></div>

[nathangardner]

The 1ds II and iii are great cameras and shoot 5fps. The 1ds II has an older style battery that doesn't last as long. The 1d

iii is 10 MP, shoots 10fps and has a 1.3x crop factor that will give you a little more reach coming from film, but then again

you may like the full frame. All are great cameras. I believe the 1d iii to be one of the best bangs for the buck in the 1

series.