Poll, R mount and 3ed party lenses

PAntunes wrote:

KevinRA wrote:

+1 to the OP on lesser reliability on DSLRs on normal phase detect AF (e.g. no live view) - - I had no luck with 5DSr and IV with Sigma wide angle fast primes - and pre then even with cross point AF points with other fast lenses - less consistent even after calibration. Never eve had an issue with a Canon lens.

Plenty of reviewers cite issue - especially Bryan at the digital picture - so whilst not proven - there is plenty of reliable reports out there backing the OPs point.

The review of the sigma art 85 1.4 on the-digital-picture:
After capturing over 600 tripod-based images of various subjects strictly for the purpose of testing AF, each capture starting in an out-of-focus condition, I found that this lens focuses consistently accurately.

https://www.the-digital-picture.com/Reviews/Sigma-50mm-f-1.4-DG-HSM-Art-Lens.aspx

"The longer I focus tested this lens, the less sure I was about its focus accuracy. I formally tested close, far and distances in between using Canon's best AF system in the EOS 5D Mark III and 1D X along with the more affordable AF system in the EOS 60D. Focus targets ranged from the Datacolor SpyderLensCal to pineapples and from flowers to people.

What I learned from the many hours (actually extended into days) spent shooting and analyzing thousands of images is that the 50 Art lens' AF cannot be completely counted on. ...sometimes, more images are out of focus than I am comfortable with.

A second copy of this lens shows similar inconsistent performance. Both this camera and the lens (via the dock) can be focus calibrated, but you cannot calibrate for inconsistency."

https://www.the-digital-picture.com/Reviews/Sigma-24mm-f-1.4-DG-HSM-Art-Lens.aspx

I shot hundreds of tripod-based f/1.4 focus accuracy test photos using a 5D Mark III, each from a slightly de-focused lens, using various AF points, both indoors and out, and saw near-ideal results from all tests. But sometimes, typically in a specific test scenario, the results were all over the place, showing AF inconsistency. I have not determined what leads to the inconsistent AF results, but they happen enough that you need to be aware of this issue.

Sitting on the ground with my elbows resting on my knees (a very stable 3-point position), I focused a mid-upper-left AF point on the sign and recomposed slightly. Over half of the results were unusably miss-focused.