p.2 #2 · 5D Mark III - 41 AF points work at f/8.0!
Yup, I don't think so. That's why I was a little bit perplexed at that Canon instructor, Ashley... I couldn't remember her last name at B&H that the other thread referred. Lenses with a native f/8.0 cannot be tricked to think that it was an f/5.6 lens.
p.2 #4 · 5D Mark III - 41 AF points work at f/8.0!
Looking forward to your results while I patiently wait for my 5D MK3.
That would be a nice combo for birding. I can get by with a 1000mm FOV if the IQ holds up. No reason it shouldn't since the 1 series works fine with that combo.
p.2 #5 · 5D Mark III - 41 AF points work at f/8.0!
Jim,
It is a mixed bag, it didn't work inside and only so-so outdoor . Inside, the AF hunted and hunted and it finally gave up . Outside, it tried and nailed the AF on distinct edges with good contrast and couldn't do that on less contrasty targets. Between you and me and the fence post, we can forget about using that combo for birding, especially in the AI Servo mode. However, you can stack two 1.4X TCs, one Canon and one generic, like a Kenko, and you have to tape the pin of the Kenko if it is a reporting TC and the stacked TCs will work well with the 500mm of yours. I had that setup a few years back and I liked it better than the 2X Mark II TC. Maybe that's the route that you want to take.
p.2 #6 · 5D Mark III - 41 AF points work at f/8.0!
AGeoJO wrote:
Jim,
It is a mixed bag, it didn't work inside and only so-so outdoor . Inside, the AF hunted and hunted and it finally gave up . Outside, it tried and nailed the AF on distinct edges with good contrast and couldn't do that on less contrasty targets. Between you and me and the fence post, we can forget about using that combo for birding, especially in the AI Servo mode. However, you can stack two 1.4X TCs, one Canon and one generic, like a Kenko, and you have to tape the pin of the Kenko if it is a reporting TC and the stacked TCs will work well with the 500mm of yours. I had that setup a few years back and I liked it better than the 2X Mark II TC. Maybe that's the route that you want to take.
Have you actually tried the stacked converters with the 500 and the 5D Mark III, or are you just assuming that it will work like it did on other bodies? I'd be interested in confirmation that it will actually lock AF reasonably well and that it doesn't just frequently hunt similar to what you described for the 2x.
p.2 #8 · 5D Mark III - 41 AF points work at f/8.0!
uz2work wrote:
Joshua,
Have you actually tried the stacked converters with the 500 and the 5D Mark III, or are you just assuming that it will work like it did on other bodies? I'd be interested in confirmation that it will actually lock AF reasonably well and that it doesn't just frequently hunt similar to what you described for the 2x.
Les
Hi Les,
No, I have not tried that setup since I sold my Kenko TC quite sometime ago. But somebody on NatureScapes reported that it did work pretty well on his 600mm f/4.0. How well it works? I am not sure. You can look up the link to that thread on the first page of this thread. That setup worked well on the 1Ds Mark III and 1D Mark III I had before using my 500mm f/4.0L IS.
p.2 #10 · 5D Mark III - 41 AF points work at f/8.0!
I tried several f/8 combinations of TC's on my 5D MK III.
The only one that worked well was my 70-200mm f/2.8 L NON-IS. This was with 1.4X and 2X TC's stacked.
My 135mm L with stacked TC's autofocused slowly for distant subjects, but get closer than about 10 ft, and it started chattering with the AF in a rapid unstable loop.
My 100-400mmL + 1.4X would focus slowly but consistently at 70mm, but at 400mm, it was a struggle and unreliable.
My 70-200mm f/4L at f/8 was unable to find focus most of the time.
p.2 #13 · 5D Mark III - 41 AF points work at f/8.0!
Just gave the 800 and 1.4III a go.
Focus is fast but a little unstable..probably 50-70 percent spot on the rest slightly off as the focus seems to jump around cycling forward and back slightly around the target. Tried dieefent AF setups the nine central points seemed to work best..
p.2 #14 · 5D Mark III - 41 AF points work at f/8.0!
I am using the same lens and my experience has been really positive. Under good lighting conditions but indoor, the AF, all 41 of them are very zippy to get the focus and not a single time did I see it jump around or being unstable. As the lighting decreased, it did get tougher for the AF to be consistent and to be fast. I didn't see any difference in the ability of various AF points to focus but I did see the difference in the target's contrast that made the difference. This is probably the reason why Canon deliberately put the official limit of the AF to only f/5.6. Again, under good lighting conditions, I feel confident that it will work well enough for AI Servo at f/8.0. In real life, I won't be using f/8.0 that much anyway although it is nice to know that if there is a need to, it can do it and do it reasonably well.
p.2 #16 · 5D Mark III - 41 AF points work at f/8.0!
Kevindar,
I am glad you tried out the AI Servo outdoor for real life shooting and confirmed my assumption that the AI Servo works . So, the pelican shots were taken at Bolsa Chica, I assume?
p.2 #18 · 5D Mark III - 41 AF points work at f/8.0!
Pelican shots were taken at the point vicente lighthouse. I think for the pelican shots I actually used the full set, auto choose, and it curiously worked the best. this may have to do more with my technique (unable to keep the focus point on the bird). I am choosing tracking option 2.
p.2 #19 · 5D Mark III - 41 AF points work at f/8.0!
Thanks kevindar and others for doing these tests. I'm thinking about ordering the Canon 1.4TC mk3 to use on my 100-400 for the time being with some taped pins. But since I am going to purchase either the 400, 500 or 600 mark2 bigwhites, I will need it for that lens anyways so might as well get it now and see how it works. I could have used it yesterday on some swans that were just a little too far out on the river for a closeup.
. Inside, the AF hunted and hunted and it finally gave up 
. So, the pelican shots were taken at Bolsa Chica, I assume?