Canon EF 70-200mm f/4L IS and polarizer problem

Has anyone had an issue with using a polarizing filter on the 70-200 f/4L lS?? With this filter on I get blurred pics. My auto focus gets them all slightly out of focus with filter on ( 100+ this morning on flying birds). Many good shots when off or using a UV clear filter. I'm using a 7D Markll , shutter priority, 1/1250, auto ISO, so it shoots at f4 usually. I did get few sharp pics in aperture priority on f9 on still birds. This is an ongoing problem. I only discovered a week ago that the problem is apparently connected to a polarizing filter.

New to this site. And fairly new to photography. First post. Thanks in advance for any insight.

Are you using a 'circular polarizer' ('CPL')? a linear polarizer ('PL', such as those from the 1970s) is not compatible with AF.

I'm using a cheap CPL filter

It's been a few years, but I have used a Hoya CPL filter with my 70-200 f/4 IS for whale watching without any issues. I had a 40D back then.

I've always used a polarizing filter on other lenses. This is the only one I have had problems with. This is a picture from this morning of a Great Egret. They are all like this.

I have been looking to replace my broken Hoya CPL, and found a couple of references related to blurred images while using some Tiffen(cheap?) CPLs. I never had any issues while using the Hoya on my 70-200.

It has been my experience that cheap filters are okay on normal to wide lenses, but are always poor at telephoto focal lengths.

Thanks for reading this and for your comments.

Just wondering: could this have something to do with the f stop? At f4 I get no sharp pics but at f9 I get a few sharp photos.

And yes it is a $10 filter but has good reviews on Amazon.

Photographically uninspired, but a good example of what is achievable with the 70-200 f/4L IS at f/5.6 with B+W brand CPL. Focus is on the topmost wire, close to the insulator, this is 1/4 of the frame area...

That is the sharpness I was hoping for with this lens. I've sent it back to Canon twice. Both times they said it was fixed.

This was taken at f/5 with a Hoya CPL. If the camera + lens focuses fine without your cheap CPL, I would try a better quality filter. You cannot expect much from a $10 CPL.

I rented a 70-200 f4L IS and stuck a Hoya CPL on it. Honestly it just couldn't take a sharp picture. It was such a shame since I was looking for a sharp travel telezoom.

There ARE cheap Hoyas (green box / blue box) and there are great Hoyas (HMC / SHMC / HD). The green or blue box ones are in the same class as Tiffens.
A Tiffen is the ONLY filter that I could see a visible abberation/distortion as I held it on front of my eye at arm's length and rotated it.
I crushed it, rather than sell the POS to an unsuspecting beginner photographer or to have someone pull it out of the trash and sell it!

dsp501 wrote in post #17946839
Has anyone had an issue with using a polarizing filter on the 70-200 f/4L lS?? With this filter on I get blurred pics. My auto focus gets them all slightly out of focus with filter on ( 100+ this morning on flying birds). Many good shots when off or using a UV clear filter. I'm using a 7D Markll , shutter priority, 1/1250, auto ISO, so it shoots at f4 usually. I did get few sharp pics in aperture priority on f9 on still birds. This is an ongoing problem. I only discovered a week ago that the problem is apparently connected to a polarizing filter.

New to this site. And fairly new to photography. First post. Thanks in advance for any insight.

Heya,

So a cheap CPL filter does a number of things, and are especially problematic on ultrawides and telephoto. You are finding out that a poorly made CPL can definitely cause you to have issues with focus and image quality. This is normal with a cheap filter. Doesn't matter if it had good reviews or not, the fact is, you're having issues with your gear. It probably worked fine for someone with a short lens doing still photography like landscape and they never saw it later than web-resolution-size. But for something intense on AF like birds in flight, you'll quickly see the difference between quality and cheap.

Since you have zero issues with your 7D2 + 70-200 F4L IS without a filter, and you only have this issue with the cheap CPL, the obvious answer is that the CPL might as well be retired to a coaster or garbage bin. $10 lesson learned, right? You are shooting a 7D2 and 70-200 F4L IS, so why put $10 resin or glass in front $2000 camera gear? Get a quality filter. It's that simple. They're not that expensive.

Marumi
Hoya
B+W

Those are good inexpensive but higher quality filters to start with. I personally use a Marumi Super DHG. I can't see any image quality loss, and I retain autofocus just fine. It was $70?

Here's the Marumi on a 200 F2.8L wide open:

No filter:

IMAGE LINK: https://flic.kr/p/qTsZ​YM

IMAGE LINK: https://flic.kr/p/qTxv​BC

Was there a reason to even shoot with the polarizer in the 1st place? Seems you could shoot Aperture priority at F4 auto iso and the shutter speed should be pretty decent.

Edit: Dang, Martin beat me to it with a lovely example even.