Will UV/Protective Filter Affect Auto Focus Performance?

Pretty much summed up in the post title, will UV/protective filter affect AF performance, in terms of accuracy?
My 85mm 1.8 misses focus sometimes, even in good/decent light. But when I do focus test with tripod and static object, it's dead on. Tried every MA adjustment available, and it seems to be best at 0.
Maybe the filter create some kind of 'ghost image' that affect the AF accuracy, because, AFAIK, the AF system detects contrast, right?
FYI, I use Hoya HMC UV and Kenko MC UV.
Thanks for all your advices.

I have never heard of this happening because of filters.

I don't see how an essentially clear filter can affect AF performance. Something else is going on.

AF is normally done with phase difference detection; contrast detection is used only in conjunction with Liveview, and is slower. At least, that's how I think it works; somebody jump in if I'm wrong, please.

GregoryF wrote in post #12700154
I have never heard of this happening because of filters.

Then neither you nor the poster below you have been around these forms enough - yes, it does and has happened.

Yes, it can affect AF performance. If you ask me, I can't figure out why you'd want to put a UV filter on the front of the your lenses anyways. It makes no practical sense. Ditch the UV filter.

Bill Ng wrote in post #12700888
Then neither you nor the poster below you have been around these forms enough - yes, it does and has happened.

Yes, it can affect AF performance. If you ask me, I can't figure out why you'd want to put a UV filter on the front of the your lenses anyways. It makes no practical sense. Ditch the UV filter.

Care to elaborate more, Bill?
What is it exactly from the filter that affect AF performance?
I put UV filter only on my 85mm because I use it to take picture of dogs and puppies, they love to sniff and lick. And yes, they can lick the front element even though I already have a hood on.
Thanks!

I have one also, from the time of unpacking, to protect the lens from scratches.
Mistake?

Well UV Filters whether you like it or not, degrades image quality and that is a FACT. If you're afraid of getting your front element scratched, then always use the hood.

cassidyphuey wrote in post #12700970
Well UV Filters whether you like it or not, degrades image quality and that is a FACT. If you're afraid of getting your front element scratched, then always use the hood.

Century old debate, from my personal testings there was zero difference when using bare lens versus one with UV filter even on longer lenses with TC, I use B+W MRC, sometimes it's even cleaner with filter (could be the result of UV haze removal), cheaper kinds will probably degrade the image, but I am more interested in hearing the theory behind AF performance impact.

Bill Ng wrote in post #12700888
Then neither you nor the poster below you have been around these forms enough - yes, it does and has happened.

Yes, it can affect AF performance. If you ask me, I can't figure out why you'd want to put a UV filter on the front of the your lenses anyways. It makes no practical sense. Ditch the UV filter.

Bill, I would like you to reference where you have seen that a UV filter (and a good one at that) has been proven to effect AF. I stand behind what I said that it should have no effect on this. Personally I do not use uv filters, but for other reasons.
I have not heard of it and I have been in photography for over 35 years.

Bill Ng wrote in post #12700888
Then neither you nor the poster below you have been around these forms enough - yes, it does and has happened.

Yes, it can affect AF performance.[...]

Reports of issues that only come up twice a year, without examples, and with no mechanisms of action being suggested do sometimes slip off my mental radar, it's true.

Please keep the discussion related to AF performance not image quality. Thanks guys.

If your only concerned about AF just test the lens with out the filter and then with it on. If The AF is slower or hunts more with the filter then you have your answer. Any time you add a layer of glass there is bound to be some impact. There are lenses I always keep a UV filter on like the
17-55 and those I almost never use a UV filter on like the 70-200 f4IS.

Andrew_WOT wrote in post #12701043
sometimes it's even cleaner with filter (could be the result of UV haze removal)

The filter in front of your sensor already removes virtually all of the UV. Any improvement you see with a UV filter is purely a placebo effect.

jwicaksana wrote in post #12701114
Please keep the discussion related to AF performance not image quality. Thanks guys.

Your question was Will UV/Protective Filter Affect Auto Focus Performance?. The fact is that any UV filter (actually, ANY filter) can, under the wrong circumstances, affect the image quality and/or auto focus performance.

The use of most decent filters will typically go un-noticed most of the time but, if the wrong combination of strong light sources (or reflections of strong light sources) in the scene exist in the wrong places, you can have problems with either image quality, auto focus performance, or both.

jwicaksana wrote in post #12700907
Care to elaborate more, Bill?
I put UV filter only on my 85mm because I use it to take picture of dogs and puppies, they love to sniff and lick. And yes, they can lick the front element even though I already have a hood on.
Thanks!

Maybe the best way is to stay out from the worry is avoid dogs licking your lens.
And put the filter off, but as far as my testing goes...

I use a cheap hoya filter on my 70-200 f/4.0L and now I didn't use it anymore, before and after I see no focus issue or IQ degradation (I do pixel-peep).

But my photography teacher says that filter (no matter what filter) does degrade IQ in a small amount. Including CPL too.