70D Autofocus @ High Apertures
So, I decided to once again take the plunge and try out 2X TC's on my 100-400, but this time with my new 70D. I had years ago tried with my 10D, but found that f/8 and f/11 max aperture lenses (with reporting disabled) were just atrocious as far as AF goes. Absolutely bunk - Canon was not lying wrt "5.6 or wider" on that camera.
But I decded to give it a whirl on my 70d, thinking "Hey, this is a WAY better AF system. Why the heck not" - and it is really night and day. I picked up a Kenko Pro 300 2x, and even though it reports f/11 back to the camera, It doesn't report "hey , I'm a TC" and thus the camera doesn't disable autofocus (no tape), and better than that - it WORKS. Really well actually. Servo and One Shot. IN MY OFFICE, of all places - my office is about 20x12 , lit by a flourescent ballast in the center, and 8 40 watt equiv flourescent spots.
The DVD case photo is in a pretty well lit area of my office, but the spraypaint can is on a shelf in a pretty dark corner. It locked on in both modes easily and readily to both, with no AF assist (these were taken with a 270EXII , AF assist flashes disabled)
The IQ - you be the judge. These were both wide open @ f/11 , 800mm. DOF is pretty shallow as you can see the DVD case is tilted slightly back and the bottom of the Seinfeld logo is fuzzy, top is in focus. (I was sitting maybe 5-6 Ft away from that DVD) To me, these are not ultra sharp @ 100% obviously, but they are pretty damn good for a zoom with a 2x TC on it. Certainly more than good enough for screen viewing, and 8x10 or maybe a bit larger printing.
Conclusion: I am really looking forward to spring. If the AF worked this well indoors, I'm excited to see what it can do out in the sun. I'm really shocked with the results. I figured that worst case I could at least get it going with live view and shoot from a tripod , but now I'm excited that I can handhold and use the VF with really pretty damn good results.