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Author Topic: Kenko TC and AF at F8  (Read 8715 times)

Mt Spokane Photography

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Kenko TC and AF at F8
« on: October 05, 2012, 09:46:46 PM »
After reading that the 1.4X Kenko PRO 300 DGX was autofocusing at f/8 with Canon super teles on 1D X Bodies, as well as reading the experiences of some who posted here with the 5D Mark III, I decided to go for it.
My TC arrived late this afternoon, and I decided to give it a try on my 100-400mmL.  At 100mm, its a equivalent of f/6.3, and the 5D MK III indicates f/6.3.
I tried it indoors in fair-good light, and it autofocused smoothly and quickly.  Then I zoomed out to 400mm which is f/8 equivalent, and I was pleased when it snapped into focus repeatedly.
Then, I decided to give it a tough test, and took it outdoors where it was rapidly becoming dark.  This is the area where TC's usually fall flat.  I zoomed out to 400mm on a far distant house with the sky still a little bid bright, and it did a fair job of autofocusing.  slower, but suprisingly fast for the situation.  The ISO level was 8000, but the image under exposed.
Then, I tried it without the sky in the background on my rose bush in deep shadows, but it would just hunt.  This was a very dark area.  Finally, I tried it on my bird feeder at ISO 12800, which was a correct exposure, and it smapped to focus quickly.  I was amazed.
Its too late to do any more testing tonight, but I'll try testing other lenses and combinations as I can make time.
Already, I can say its worth the price over a Canon 1.4X MK II TC as long as you do not need weather sealing.

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Kenko TC and AF at F8
« on: October 05, 2012, 09:46:46 PM »

WesternGuy

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Re: Kenko TC and AF at F8
« Reply #1 on: October 10, 2012, 09:26:10 PM »
Do you have any more test results to report?  If this unit will focus when it is on the the new 600mm f4L IS II, then it is probably worth the extra $$.  Just curious, that's all.

WesternGuy

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Re: Kenko TC and AF at F8
« Reply #2 on: October 10, 2012, 09:41:17 PM »
Also can you compare sharpness to the Canon 1.4 mk.iii please.
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neuroanatomist

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Re: Kenko TC and AF at F8
« Reply #3 on: October 10, 2012, 10:09:27 PM »
If this unit will focus when it is on the the new 600mm f4L IS II, then it is probably worth the extra $$.

 ???

Certainly it will AF. So will the Canon 1.4xIII, since either 1.4x TC will make an f/4 lens into an f/5.6 lens, and all Canon bodies can AF with an f/5.6 lens.

Did you mean will the Kenko 2x allow AF with the resulting f/8 combo. A poster on a bird forum reported that it will, but also showed that unlike the Kenko 1.4x which has decent IQ, their 2x turns a sharp lens to mush.
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Mt Spokane Photography

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Re: Kenko TC and AF at F8
« Reply #4 on: October 10, 2012, 10:34:04 PM »
If this unit will focus when it is on the the new 600mm f4L IS II, then it is probably worth the extra $$.

 ???

Certainly it will AF. So will the Canon 1.4xIII, since either 1.4x TC will make an f/4 lens into an f/5.6 lens, and all Canon bodies can AF with an f/5.6 lens.

Did you mean will the Kenko 2x allow AF with the resulting f/8 combo. A poster on a bird forum reported that it will, but also showed that unlike the Kenko 1.4x which has decent IQ, their 2x turns a sharp lens to mush.
+1.
Thanks Neuro.  hand surgery tody, so I can't type well much less test cameras.  It did work very well on my old 10D - suprising.  I do not have many f/5.6 lenses to test it with.

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Re: Kenko TC and AF at F8
« Reply #5 on: October 10, 2012, 11:24:14 PM »
Hope the surgery went well!

Regarding the Kenko 1.4x, maybe I blew it.  I could have just gotten that to use with my 100-400 for a 560mm f/8 lens with AF.  Let's say the Kenko is as good optically as the 1.4xII - that can't be too bad compared to the 600mm f/4L IS II, can it?!?

Actually, on a serious note, Art Morris is really pleased about the Kenko 1.4x and the 800/5.6L IS.  He's got some very nice image to back that up.  But interestingly, when I look at TDP's ISO 12233 crops, the optical performance of the 800/5.6 + 1.4x (no real difference between MkII vs. MkIII there) and the 600/4 II + 2x (link), they look pretty similar (which makes sense - the 600 II is a better lens, and the 600 II + 1.4x is optically a tiny bit better than the 800/5.6).  So, for static subjects (where Live View AF would work fine), the 600 II plus Canon 2x would be worth a try...

Now I just need to decide if it's worth swapping the 2xII that I have for a 2xIII.  There is a chart comparison for the 2xII vs. 2xIII with the 70-200 II, and there's a marginal improvement - since I'll occasionally use that combo (when I don't want to bring both the 70-200 II and the 100-400), it may be worth upgrading just for that...
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Re: Kenko TC and AF at F8
« Reply #6 on: October 11, 2012, 12:39:33 AM »
Hope the surgery went well!

Regarding the Kenko 1.4x, maybe I blew it.  I could have just gotten that to use with my 100-400 for a 560mm f/8 lens with AF.  Let's say the Kenko is as good optically as the 1.4xII - that can't be too bad compared to the 600mm f/4L IS II, can it?!?

Actually, on a serious note, Art Morris is really pleased about the Kenko 1.4x and the 800/5.6L IS.  He's got some very nice image to back that up.  But interestingly, when I look at TDP's ISO 12233 crops, the optical performance of the 800/5.6 + 1.4x (no real difference between MkII vs. MkIII there) and the 600/4 II + 2x (link), they look pretty similar (which makes sense - the 600 II is a better lens, and the 600 II + 1.4x is optically a tiny bit better than the 800/5.6).  So, for static subjects (where Live View AF would work fine), the 600 II plus Canon 2x would be worth a try...

Now I just need to decide if it's worth swapping the 2xII that I have for a 2xIII.  There is a chart comparison for the 2xII vs. 2xIII with the 70-200 II, and there's a marginal improvement - since I'll occasionally use that combo (when I don't want to bring both the 70-200 II and the 100-400), it may be worth upgrading just for that...
I took some pain killer, so it feels better now.  The surgery went fine, my left hand was done 3 weeks ago and is healing well.  I want to be healed before winter, I'm out in the country and have to run my tractor to plow my almost 1/4 mile driveway.  I need a good grip sometimes when it starts sliding.
I'll also want to try the TC on my 100L, more magnification is sometimes handy, I don't have the mp-e 65.  I did put it on my 24-105 where it worked fine, but there is little point to using it there.
I do have a number of older consumer grade lenses which are marginal without a TC, but I might try it with them just to see if they autofocus.
I'm also curious about combinations of TC's,  With my 1D MK III I've seen my 1.4X and 2X autofocus even at f/11.

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Re: Kenko TC and AF at F8
« Reply #6 on: October 11, 2012, 12:39:33 AM »

AlanF

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Re: Kenko TC and AF at F8
« Reply #7 on: October 11, 2012, 12:52:26 AM »
I tested the Kenko 1.4x last week on my 7D and 100-400mm L, and it worked fine. The focus was quick and the IQ better than the without scaled by 1.4 in Photoshop.  But, it wouldn't autofocus when stacked on my favourite hand-held 600 mm combo of a Canon 2xtc III with a 300mm f/2.8 II. The 2xtc slows down the 300 focussing by a factor of 4 and the extra 1.4 Tc is too much. The reproducibility of focus of the Mk II 300mm is far better than that of the 100-400mm so perhaps the sloppier focussing of the older lens is more tolerant to f/8.
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Re: Kenko TC and AF at F8
« Reply #8 on: October 11, 2012, 01:47:53 AM »
If this unit will focus when it is on the the new 600mm f4L IS II, then it is probably worth the extra $$.

 ???

Certainly it will AF. So will the Canon 1.4xIII, since either 1.4x TC will make an f/4 lens into an f/5.6 lens, and all Canon bodies can AF with an f/5.6 lens.

Did you mean will the Kenko 2x allow AF with the resulting f/8 combo. A poster on a bird forum reported that it will, but also showed that unlike the Kenko 1.4x which has decent IQ, their 2x turns a sharp lens to mush.
+1.
Thanks Neuro.  hand surgery tody, so I can't type well much less test cameras.  It did work very well on my old 10D - suprising.  I do not have many f/5.6 lenses to test it with.

re: hand surgery.  get well soon
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WesternGuy

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Re: Kenko TC and AF at F8
« Reply #9 on: October 11, 2012, 03:53:29 AM »
Okay guys, I am a bit new to this forum and it seems like I need a little help here.  I just tried my Canon 1.4x III on my 100-400 and I could not get it it AF at 100mm or at 400mm on my 1D X.  Am I doing something wrong?  If so, can anyone give me any suggestions as to how to make this happen?  Thanks.

WesternGuy

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Re: Kenko TC and AF at F8
« Reply #10 on: October 11, 2012, 06:23:38 AM »
I just tried my Canon 1.4x III on my 100-400 and I could not get it it AF at 100mm or at 400mm on my 1D X.  Am I doing something wrong?  If so, can anyone give me any suggestions as to how to make this happen? 

What you're doing 'wrong' is using the Canon 1.4x.  The 100-400mm is an f/4.5-5.6 lens, so putting on a 1.4x TC makes it an f/6.3-8 lens.  The 1D X requires a max aperture of f/5.6 for AF to work (note that previous 1-series bodies could AF with an f/8 combo, although only with the center AF point). 

Unlike the Canon TCs, the electronics Kenko 1.4x and 2x TCs somehow 'spoof' the camera into not seeing the TC for AF purposes (the aperture reported in EXIF does reflect the TC being there).  Side note, the 1D X also does not see the TC for metering, so you need to apply one stop of EC with the Kenko 1.4x and 2 stops with the Kenko 2x, other bodies, e.g. 5DIII, 7D, don't seem to have the metering effect, but still AF fine).

The reason (some) people are up in arms over this is that it pretty clearly shows that the 1D X (and other bodies) can AF at f/8, but Canon is locking that function out in firmware.
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Re: Kenko TC and AF at F8
« Reply #11 on: October 11, 2012, 09:42:32 AM »
Looks like someone in Canon is under huge (short term) pressure to boost profitability... the new buzzword (again) is selling high margin products... f5.6 lenses probably have better margins than f8. I can understand why the customers are feeling like their interests did not matter. 
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Re: Kenko TC and AF at F8
« Reply #12 on: October 11, 2012, 09:43:16 AM »
  hand surgery tody, so I can't type well much less test cameras.  It did work very well on my old 10D - suprising.  I do not have many f/5.6 lenses to test it with.

Hope the recovery goes well.
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Re: Kenko TC and AF at F8
« Reply #12 on: October 11, 2012, 09:43:16 AM »

WesternGuy

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Re: Kenko TC and AF at F8
« Reply #13 on: October 11, 2012, 03:35:23 PM »
I just tried my Canon 1.4x III on my 100-400 and I could not get it it AF at 100mm or at 400mm on my 1D X.  Am I doing something wrong?  If so, can anyone give me any suggestions as to how to make this happen? 

What you're doing 'wrong' is using the Canon 1.4x.  The 100-400mm is an f/4.5-5.6 lens, so putting on a 1.4x TC makes it an f/6.3-8 lens.  The 1D X requires a max aperture of f/5.6 for AF to work (note that previous 1-series bodies could AF with an f/8 combo, although only with the center AF point). 

Unlike the Canon TCs, the electronics Kenko 1.4x and 2x TCs somehow 'spoof' the camera into not seeing the TC for AF purposes (the aperture reported in EXIF does reflect the TC being there).  Side note, the 1D X also does not see the TC for metering, so you need to apply one stop of EC with the Kenko 1.4x and 2 stops with the Kenko 2x, other bodies, e.g. 5DIII, 7D, don't seem to have the metering effect, but still AF fine).

The reason (some) people are up in arms over this is that it pretty clearly shows that the 1D X (and other bodies) can AF at f/8, but Canon is locking that function out in firmware.
neuroanatomist, thank you for the explanation.  Hopefully, someone in the Canon organization will wake up and see what the competition is doing and upgrade the firmware.  Guess I need to put a Kenko 1.4x in my next order.

WesternGuy

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Re: Kenko TC and AF at F8
« Reply #14 on: October 11, 2012, 05:21:45 PM »
I tested the Kenko 1.4x last week on my 7D and 100-400mm L, and it worked fine. The focus was quick and the IQ better than the without scaled by 1.4 in Photoshop.  But, it wouldn't autofocus when stacked on my favourite hand-held 600 mm combo of a Canon 2xtc III with a 300mm f/2.8 II. The 2xtc slows down the 300 focussing by a factor of 4 and the extra 1.4 Tc is too much. The reproducibility of focus of the Mk II 300mm is far better than that of the 100-400mm so perhaps the sloppier focussing of the older lens is more tolerant to f/8.

Alan -

Were you able to use all AF points?  I've only been able to use the outer left and right points (4 on each side) with that same combination; I'd love to get it working with all, or at least, most, points.

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Re: Kenko TC and AF at F8
« Reply #14 on: October 11, 2012, 05:21:45 PM »