tested every combo of 70-200II, 100-400, 2x III, and Kenko Pro 2x DGX

Hi folks,

I only joined POTN a couple days ago, but I thought it was time to contribute something besides just replying to other threads.

Seeing a lot of requests for sample shots with the Extender 2x III, I decided to post the results of a recent comparison between that and the Kenko Pro 2x DGX on the 70-200mm f/2.8L IS II. While I was at it, I decided to test every combination of these three plus the 100-400mm f/4.5-5.6L IS (eight combinations in all).

Since the forum image size limit is too small (each crop below is 800x800 at full size), I'm just going to link to my Flickr post, which has more detail about the test. Please read about the test setup before raising any objections - I controlled for many variables, but I can only do so much with the time, space, and equipment available. And before you ask: yes, I did test the corners too, but the test was inconclusive - i.e., I was seeing some inconsistencies that I could not eliminate experimental error as an explanation for.

To sum up a few image-quality observations from the linked Flickr posts:

- The Kenko resolves more than the Canon TC.
- The Canon TC has better contrast and color than the Kenko.
- A single 2x TC beats upsampling the bare lens.
- Stacked 2x TCs resolve more than upsampled single 2x TCs, but not by much, and at the cost of further deterioration of color and contrast (not to mention 2 stops).
- My pick of the litter is 100-400 + 2x III, because I value contrast more than resolution - although I can easily see the case for the 100-400 + 2x DGX too. Then again, I rarely shoot manual-focus at 800mm f/11, so this is a largely theoretical preference.
- As for 70-200II+2xIII vs. 100-400, the latter clearly holds the image quality edge at f/5.6 and a slight edge at f/8 (also true in practice, where the loss of contrast with the TC is more painful than the lowish resolution).

Having said that, I'm leaning towards keeping the 2x III, purely for practical reasons. I don't see myself ever carrying both the 70-200 and 100-400 anywhere, so if it's a choice between somewhat reduced image quality and AF speed at 200-400mm and somewhat greater weight and bulk versus the loss of 70-100mm, shallow DoF capability, low-light capability, and every other advantage of the 70-200 within its native range... well, it's a tough call. And yes, I realize I'm lucky to have the choice to make.

IMAGE LINK: http://www.flickr.com …ornsarebitter/5​450404086/

Cool test, I'll check out the full size results tomorrow.

Hmmm, very interesting. What really stands out, for me, is the huge difference between the 100-400 and the 70-200 + TC. The 100-400 is a lot better in terms of image clarity which is not what I'd expected. It shows in the image above and is even more obvious in the original image on your Flickr page.

Is the AF speed any better with the Kenko 2X on the 70-200 MK II vs. the Canon 2X III on the same lens?

jrscls wrote in post #11853215
Is the AF speed any better with the Kenko 2X on the 70-200 MK II vs. the Canon 2X III on the same lens?

The Kenko doesn't AF on the 70-200II, so I guess the answer is no? Oddly, it does on the 100-400, though. The hit rate is essentially zero percent with the latter combo, though. I use manual focus exclusively with the Kenko.

acornsarebitter wrote in post #11853232
The Kenko doesn't AF on the 70-200II, so I guess the answer is no? Oddly, it does on the 100-400, though. The hit rate is essentially zero percent with the latter combo, though. I use manual focus exclusively with the Kenko.

Thats odd AF fails on the MKII at f5.6 with the Kenko 2x Pro 300 DGX.

How old is your DGX ?

When Kenko initially released the Kenko 1.4 Pro 300 DGX it was incompatible with the 70-200 F4L IS USM & 3 other Canon lenses also. The optics were the exact same as the DG version but Kenko redesigned the internal circuitry to report more extensive data back to the body. 1st releases of this DGX model circuitry had to be redesigned once again to my knowledge unless im mistaken.

You may have one of the originally released DGX versions or have discoverd a new Kenko compatibility issue with the 70-200 MKII lens.

http://www.thkphoto.co​m …ko/pro300af2x1_​4xdgx.html

http://www.kenkoglobal​.com/TP-MC7AF2X-DGX.html

What is really odd is you stating AF works with the 100-400L at f11.0 since this 2x is a reporting TC, unless you taped the pins as the below:

http://www.michaelfurt​man.com/taping_the_pin​s.htm

Thanks for the tests.

Regards,

The 1-4 IS still outresolves and out-contrasts the 7-2 IS II at 400mm wide open: http://www.the-digital-picture.com …omp=0&FLIComp=7​&APIComp=0

The ole' dust pumper still holding its own

Silverfox1 wrote in post #11853795
Thats odd AF fails on the MKII at f5.6 with the Kenko 2x Pro 300 DGX.

How old is your DGX ?

When Kenko initially released the Kenko 1.4 Pro 300 DGX it was incompatible with the 70-200 F4L IS USM & 3 other Canon lenses also. The optics were the exact same as the DG version but Kenko redesigned the internal circuitry to report more extensive data back to the body. 1st releases of this DGX model circuitry had to be redesigned once again to my knowledge unless im mistaken.

You may have one of the originally released DGX versions or have discoverd a new Kenko compatibility issue with the 70-200 MKII lens.

http://www.thkphoto.co​m …ko/pro300af2x1_​4xdgx.html

http://www.kenkoglobal​.com/TP-MC7AF2X-DGX.html

What is really odd is you stating AF works with the 100-400L at f11.0 since this 2x is a reporting TC, unless you taped the pins as the below:

http://www.michaelfurt​man.com/taping_the_pin​s.htm

Thanks for the tests.

Regards,

Yeah, that's what I said: it struck me as odd that the AF "works" since it does report the f-stop correctly on the 100-400 - if I had taped the pins, it would not have reported correctly. I didn't think much about it, since the AF accuracy is next to non-existent anyways. Yes, it was one of the first DGXs, as I ordered a DG from B&H and got this instead, even though DGXs were not on sale in the U.S. yet at the time. I got the 70-200II eight months after the DGX, so I just chalked it up to the usual forward-compatibility problems with third-party lenses. It does not report the aperture correctly for the 70-200II.

acornsarebitter wrote in post #11854946
Yeah, that's what I said: it struck me as odd that the AF "works" since it does report the f-stop correctly on the 100-400 - if I had taped the pins, it would not have reported correctly. I didn't think much about it, since the AF accuracy is next to non-existent anyways. Yes, it was one of the first DGXs, as I ordered a DG from Adorama and got this instead, even though DGXs were not on sale in the U.S. yet at the time. I got the 70-200II eight months after the DGX, so I just chalked it up to the usual forward-compatibility problems with third-party lenses. It does not report the aperture correctly for the 70-200II.

Tell me after you look on the barrel of the 2x DGX what color dot does it have on it ? Red or Blue ?

I recently ordered the Kenko 2x MC4 DGX and it has a Blue Dot which i believe indicates the revised internal circuitry to make them compatible with not only AF capability at F5.6 but also IS compatibilty which was one of the probelms with the F4 IS when the 1st batch of DGX`s was released.

I just performed tests with the 4 element Kenko 2x MC4 DGX + 70-200 MKII and the AF is very responsive at 400mm even on an overcast gloomy day ISO 200.

I also tested the MC4 on my 100-400L and since it is a reporting TC the AF would not work as expected, but shows F11.0. I will be posting all the result pics soon.

Regards,

Silverfox1 wrote in post #11856153
Tell me after you look on the barrel of the 2x DGX what color dot does it have on it ? Red or Blue ?

I recently ordered the Kenko 2x MC4 DGX and it has a Blue Dot which i believe indicates the revised internal circuitry to make them compatible with not only AF capability at F5.6 but also IS compatibilty which was one of the probelms with the F4 IS when the 1st batch of DGX`s was released.

I just performed tests with the 4 element Kenko 2x MC4 DGX + 70-200 MKII and the AF is very responsive at 400mm even on an overcast gloomy day ISO 200.

I also tested the MC4 on my 100-400L and since it is a reporting TC the AF would not work as expected, but shows F11.0. I will be posting all the result pics soon.

Regards,

If you mean the lens-side mount attachment reference dot, it's red, just like other EF lenses.

Strange, but after reading this, I tried this combo again to see if turning the IS off made it capable of AF, and it worked! But then I turned the IS on and it still worked. Tried every combination of power cycling with the IS on or off at startup, and it still worked. This is after a half dozen previous attempts at AF with this combo where I was getting zero AF response.

Having said that, I'm not really excited, because while the AF works, like with the 100-400, it never locks onto anything without more work than it would take to just MF. Even if the AF could focus on a speeding bullet, the build and image quality are not good enough for me either. I 've simply filed the Kenko under "Reason #11 to Stick With Canon".

Huh, something doesnt look right here... Why does the 70-200 w/ 2X III wide open look sharper than the 70-200 w/o the 2X III wide open?

ben_r_ wrote in post #11856464
Huh, something doesnt look right here... Why does the 70-200 w/ 2X III wide open look sharper than the 70-200 w/o the 2X III wide open?

As I said, please read the test description in the linked Flickr posts. The bare 70-200 frames were upsampled 8x (in each dimension) versus only 4x upsampling for the 70-200+2xTC. It is indeed the case that for a fixed camera-to-subject distance, an upsampled bare lens will not be as sharp as that lens with the 2x III attached.

acornsarebitter wrote in post #11856424
If you mean the lens-side mount attachment reference dot, it's red, just like other EF lenses.

Strange, but after reading this, I tried this combo again to see if turning the IS off made it capable of AF, and it worked! But then I turned the IS on and it still worked. Tried every combination of power cycling with the IS on or off at startup, and it still worked. This is after a half dozen previous attempts at AF with this combo where I was getting zero AF response.

Having said that, I'm not really excited, because while the AF works, like with the 100-400, it never locks onto anything without more work than it would take to just MF. Even if the AF could focus on a speeding bullet, the build and image quality are not good enough for me either. I 've simply filed the Kenko under "Reason #11 to Stick With Canon".

If your DGX has the RED dot then you have the 1st batch release that has compatibilty issues with 4 lenses even before the 70-200 MKII was released. You have now found a 5th lens !

I also have the RED dot for the lens attachment indicator but next to the nomenclature that says " Made in Japan" is the BLUE dot.

As i mentioned the 2x MC4 DGX i recently received has the BLUE dot and works absolutely fine with the 70-200 MKII and would with the previous 4 Canon lenses that were incompatible with the RED dot DGX releases.

Regards,

jrscls wrote in post #11853215
Is the AF speed any better with the Kenko 2X on the 70-200 MK II vs. the Canon 2X III on the same lens?

Now that the AF has started working with the Kenko + 70-200II, I can confidently state it is light years faster than the AF with the 2x III. Completely useless, but really fast.

acornsarebitter wrote in post #11856614
Now that the AF has started working with the Kenko + 70-200II, I can confidently state it is light years faster than the AF with the 2x III. Completely useless, but really fast.

I dont have the Canon 2X III to compare but the Kenko 2X MC4 DGX i just tested is very fast & reponsive even on the gloomy overcast day here using ISO 200 at 400mm.

Regards,