Hoya CPL defocusing photos

Good afternoon

Yesterday, I went out with my Canon 5D Mk III and 70 - 200mm f4L (non-IS) lens fitted with an expensive Hoya "digital" CPL. It was a nice sunny day and I took static and moving subjects. Sadly, all of my photos came back defocused when used with the CPL. All of the photos were in focus without the CPL . I was shooting at various focal lengths but mainly at the 135-200mm end.

Now before anyone asks, I am a semi pro (not a novice) and have never had this problem with my 24-105 f4L lens, - even when not using IS. And historically, I could easily hand hold (with the 5D III/70-200mm) down to 1/60sec shutter speed with the CPL on the front of the lens. Even at "silly" shutter speeds of 500/640, the photos were still defocused.

Have I a dodgy CPL filter?

Start by posting examples.

Very best,

I am new to this forum. How do I post examples - and at what resolution?

Thanks

I don't use dropbox - is it free?

The photos don't look like a problem with camera shake; they look smeared or double.

Can't I post directly to the forum?

Right here we go:

Exif data as follows:

POTN1: FL 126mm, 1/400sec at f7.1 and ISO 200 with Hoya Pro 1 CPL

POTN2: FL 104mm, 1/640sec at f8 and ISO 500 (!) with Hoya Pro1 CPL


Camera: Canon 5D Mark III with 70-200 F4L lens and images reduced to 50% to conform with forum file size. I focused on the red signal which is the subject of interest

Thanks

Here's another picture without the CPL

Exif data: FL 200mm, 1/250mm at f10, ISO160

Heya,

Try uploading 1:1 crops of the areas you want inspected, like the red thingybob.

Very best,

MalVeauX wrote in post #19092098
Heya,

Try uploading 1:1 crops of the areas you want inspected, like the red thingybob.

Very best,

Here we go:

collectingrocks wrote in post #19092103
How do I do that please?

Open you photo in a photo editor. View it at 100% (1:1 pixel scale). Crop it down to something around 1600 pixels or less to be able to post here without it scaling down . Label them so everyone can tell which is which with respect to you using a CPL or not. We cannot see the ghosting or blur at a full resolution image scaled down, so show us a 1:1 pixel scale and simply crop it to a single area to focus on.

Also, you really need to do a controlled test. These photos are all different local-lengths, focal-ratios, different exposure times, different ISO, etc, no idea what the camera selected for focus point, random camera settings, leads me to think it was just on full auto / P or something like that. This is not a good way to evaluate focus, depth of field, etc, and think a filter is to blame. Before getting to this, go setup on a tripod, pick a subject, control all your settings to be the same and re-create some images with and without the filter to get a better idea of things. Otherwise, this is really just too random to make clinical judgement from.

Very best,

No CPL

If you did this already, please forgive me, but did you check that the filter is in place in the ring? Or that the ring which allows rotation of the filter can only rotate, and it doesn't move back and forth?
A friend once managed to knock a filter out of the ring, but without breaking the glass, so the filter was tilted.

Capn Jack wrote in post #19092119
If you did this already, please forgive me, but did you check that the filter is in place in the ring? Or that the ring which allows rotation of the filter can only rotate, and it doesn't move back and forth?
A friend once managed to knock a filter out of the ring, but without breaking the glass, so the filter was tilted.

Yes, most definately

Oh and the CPL is a 67mm Hoya Pro1 CPL

Technique:

• Run your A-B comparisons ON TRIPOD to eliminate the possibility of your shake contributing to blur.
  
• Shoot your shots with exact same focus setting (put lens on Manual Focus after focusing) and be careful not to turn the MF ring on the lens.
  

I had the exact same thing happen on my 100-400 v1. Somewhere here is a old thread where I posted debug pictures. My solution was to not use a CLP with my 100-400. It just doesn't like filters.

Yes, many stories of the 100-400 results with filter not being terrific.

OTOH that same story generally does not plague any of the Canon 70-200mm of any vintage or max f/stop.