5D MarkIII focuses very well at f/8

[Renato]

I have been a 7D user for 3 years and recently was able to test it with the Kenko C-AF 2X Teleplus Pro 300 DGX and a EF 300mm f/4 . The results were amazing read some results here:

http://10000birds.com/bird-photography-equipment-teleconverters-for-7d-and-5d-miii.htm

I have now upgraded to the 5D Mark III, and I am also pleased to inform that the 5D Mark III works even better than the 7D with the Kenko extender. I have tested the EF 300mm f/4 with the Kenko 2X with amazing results.

The 5D MIII has worked extremely well even under average light conditions. Under very low light situations there is a some focusing hunt but this can be fixed by switching to zone AF and using the center nine focusing points.

I also tried the 5D MIII and the Kenko 2X with the 100-400 f/5.6 lens and it works only under good light at f/11! In a couple of weeks I will get the Kenko 1.4X and try it with the 100-400 lens. I will report the results then. Forget about the Canon TC they do not allow the 5D or the 7D to work at f/8 or f/11.

 

[wickidwombat]

nice I thinkt he newer versions that correctly report AF dont work ie the DG-X versions and I have tested my canon 2x extender 3 which doesnt get AF, IQ is good though with manual focus

 

[Mt Spokane Photography]

I've found that my 5D MK III would not AF with most Canon lenses at f/8, much less at f/11. I taped contacts of my canon TC's to do the test.

I've found in the past that its a hit and miss thing, some bodies / lenses are a little better or worse, so one body might AF with a 100-400 while another will not.

My 100-400mm f/3.5-5.6 would AF at the short end where it is f/3.5 fine with a 1.4X TC, but it just hunted at 400mm.

My old 70-200mm f/2.8 non IS would AF fine and reasonably quickly at f/8 with a 1.4XC and 2X TC stacked. i also had issues with lenses chattering when focusing on a close object well beyond minimum focus distance, while distant objects worked well.

So, I would not recommend that some one buy a camera believing that they could AF at F/8, many have reported the same results as I had, so be happy that you got a outlier thats exceptional.

 

[spinworkxroy]

Different lens and different model of Kenko TC will give different results..
NOT all will focus at f8
I'm thankful my Kenko 1.4x with my tamron 70-300f4-5.6 DOES indeed focus very well at f8 at 300mm..
But i've also read that many who owns the same Kenko doesn't focus…no one knows for sure why…could be different generatino Kenkos work differently

 

[GuyF]

Just got my mk3 on Saturday and so far very impressed (moved up from a 40D).

I used my Kenko 300 DG 1.4x and 2x convertors individually and stacked together on my 300mm f2.8 IS and it focused fine though it did hunt a little with the two convertors stacked. With the convertors stacked together the EXIF data reported the combination as 300 + 1.4x. I'm guessing it will report whatever one is attached directly to the lens and "ignores" the one attached to the body.

Anyway, I'd only use them stacked for shots of the moon.

So there you go, the mk3 will focus at f8.

 

[Renato]

I've found that my 5D MK III would not AF with most Canon lenses at f/8, much less at f/11. I taped contacts of my canon TC's to do the test.

I've found in the past that its a hit and miss thing, some bodies / lenses are a little better or worse, so one body might AF with a 100-400 while another will not.

My 100-400mm f/3.5-5.6 would AF at the short end where it is f/3.5 fine with a 1.4X TC, but it just hunted at 400mm.

My old 70-200mm f/2.8 non IS would AF fine and reasonably quickly at f/8 with a 1.4XC and 2X TC stacked. i also had issues with lenses chattering when focusing on a close object well beyond minimum focus distance, while distant objects worked well.

So, I would not recommend that some one buy a camera believing that they could AF at F/8, many have reported the same results as I had, so be happy that you got a outlier thats exceptional.

I tried the contact taping trick and had the same problem with the Canon TCs but with KENKO its is a different story, you do not need to tape anything! My recomendation is borrow it or rent it and test it before you buy it. For me it works GREAT!

Today I used the 300 f/4 with Kenko 2X plus Canon 1.4X for f/11 and got good results under good light. It does not focus with low light of low contrast subjects, but it is f/11!!!!

 

[Marsu42]

nice I thinkt he newer versions that correctly report AF dont work ie the DG-X versions

Surprisingly, this doesn't seem to be the case as far as I've read (I've got the 1.4 dgx on my 60d for my 70-300L) - the newer Kenko somehow manages to put the correct aperture in the exif, but still fool the camera into af'in at f8.

But everyone here please always exactly (!) specify what tc you're using (Kenko dg, dgx) and when you bought it, Kenko seems to silent update the tcs without customers knowing it.

 

[Mt Spokane Photography]

Just got my mk3 on Saturday and so far very impressed (moved up from a 40D).

I used my Kenko 300 DG 1.4x and 2x convertors individually and stacked together on my 300mm f2.8 IS and it focused fine though it did hunt a little with the two convertors stacked. With the convertors stacked together the EXIF data reported the combination as 300 + 1.4x. I'm guessing it will report whatever one is attached directly to the lens and "ignores" the one attached to the body.

Anyway, I'd only use them stacked for shots of the moon.

So there you go, the mk3 will focus at f8.

Yes, mine focused at f/8 with my 70-200mm f/2.8 and two Canon TC's stacked, it focused quickly and well However, I also tried it with various canon lenses and TC combinations taped contacts, and the results varied from no focus at all to struggling, to focus well on distant objects only.

You cannot do a test on one lens and claim it focuses on all, it doesn't.

 

[Renato]

I have learned that with the EF 300 f/4 you cannot register the AF Microadjustment for the lens with a Kenko extender. I calibrated my EF 300 f/4 plus Kenko 2X Telepluspro 300 and then registered the microadjustment. Immediately my camera locked and would not focus so what I had to do is take the battery out, take away the AF Microadjustment and put a generic adjustment (ALL) for this lens. Luckily the microadjustment for the lens alone is +14 and the lens with the Kenko extender is +12 so I set the micradjustment to ALL at +13. Now every time I put another lens that has a microadjustment I have to enable the automatic adjustment function. Otherwise the Keno extender works flawless with my EF lens. Also note that the Kenko that I used (2X Telepluspro 300 DGX) does not work with lenses that are not telephotos. If you want to use a Kenko with a 50 mm or smaller you have to get a different extender.

Here are the specifications for the Kenko I use 2X: http://www.kenkoglobal.com/TP-PRO300AF-DGX1_4-2X.html