Sigma 500 f4 Sport. Erratic AF. Corrections?

Started Feb 15, 2019 | Discussions thread
ManosSKG New Member • Posts: 17
Re: Sigma 500 f4 Sport. Erratic AF. Corrections?

ARClark wrote:

ManosSKG wrote:

Precise calibration is important. I never used a Sigma that doesn't need fiddling, some more than others. My copy was severely focus shifting (only 1 in 3 shots sharp) and I brought the lens to a fine balance throughout the range with more than 90% keeper rate (ie at par with OEM glass). I find calibrating using visual aids, not adequate though (ie sloped rulers etc). I use my in camera auto FT system in combination with the dock. I change my figures in the dock and use the auto FT system as a reference point until I get a 0 to 1-+ value. Steve Perry's target works fine.

I need to clarify this. So in my experience, the focus shifting only occurred during high speed bursts. Single shots were nice and sharp. I’m just wondering how running the static calibration to get single images sharp corrected the dynamic focus-shift phenomenon during bursts? Not saying it didn’t happen. I just don’t understand the correlation.

I am not technically educated, so my answer is that I have absolutely no idea. Indeed single shots appeared more precise to me, or at least with much less variance to make a difference. Mind it that this issue is only reported with specific Nikon models, which probably means that its all about the communication of the lens with those bodies. I wander how the lens performs with the new Nikon mirrorless bodies. In theory, there should be no issues whatsoever.

In my case the lens was so severely focus shifting that only 1 out of 3 shots was in focus. All I know is that after properly MFT via the dock, I have an approx 90% keeper rate in a burst of 10 shots, which is equivalent to OEM glass. My friend owns the E FL and our shots are pretty similar to be honest. What I don't like as much is the OS and even after trying the typical suggested settings, I still like the Nikon's VR more.

 ManosSKG's gear list:ManosSKG's gear list
Nikon D500 Sigma 150-600mm F5-6.3 | C Sigma 500mm F4 Sport
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