Good news ! I received my 70D back, this time, after the third trip, Canon replaced the camera with another one. I'm still testing it, at the moment I can only say that I get almost the same results as NebrGuy.
Despite having a better AF alignment, I still get some missed shoots with my 18-35 Sigma lens. I still wish that the red square was a little bit more centered. The 18-35 does seem to be very sensitive to misaligned AF sensor, my other Sigma lens (the old 35mm f/1.4) seems to cause less issue. I'll need to check if theres not an issue with my 18-35mm and will try doing some MFA. I only did some quick tests, will do further testing during the week-end...
Nevertheless, this camera is much
better than the previous one. I'll try to identify the scenario where focus is random, not sure if I'm going to send it back for a fourth time.
Scoobert wrote in post #17123146
Nope, you need a 2.8 or faster lens to test the center point focus.
No the test should work with both fast and slow lens (see my post above, I compared NebrGuy focus sensitive area with both fast and slow lens... they match). I will confirm that on my camera during this week-end.
But a fast lens is still needed to show to Canon's technicians that there is a focus issue. If Canon technicians hear about misaligned sensitive AF area, they'll check the camera for parallax issue in the viewfinder, that won't fix the camera.
ddk2001 wrote in post #17122847
=ddk2001 ;17122847]So . . . . . . . . .
My refurbished 70d arrived today. I spend most of my time shooting my kids' sports with my 70-300L. Should I even bother testing this thing? Or - just go shoot?
Wait - I don't have any lens faster than 2.8. So - I can't test it anyway - right?
The test is still useful even if you don't have a focus issue, because you'll know in advance where to aim the camera to be 99% percent sure to get what you want in sharp focus. You also don't want to discover that after your warranty has expired...
Here is an example showing why this test is useful :
My 60D leftmost focus point is a bit misaligned, I definitely noticed that when taking some pictures (see my post above). At first, I didn't do the AF sensor coverage measurement (because, as my 70D was a mess, I bought the 60D the day before snapping some pictures). Thankfully I knew some misalignment issue could cause what I observed during shoot. So I was able to change my aiming to get always sharp focus where I wanted.
But unlike the 60D, and the 7D, on the 70D, most of the focus marks are less than half covered by the sensing AF element, that also seems true even on perfectly working cameras (Canon must have crippled the AF sensor...).
That incomplete coverage is definitely something you want to know, otherwise you can get lots of blurry pictures for no apparent reason. Imagine your kid running while being aligned in the right half of focus point N°3 or 14... you would have focused on the background !
Good news is that if your centerpoint seems as "well" aligned as mine and NebrGuy, there's a good chance that your camera will give identical results. So no need to do all 19 focus points.