cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Blurry images - lens or filter causing the problem?

mikeB
Contributor
Hi there,

I recently picked up a polarizing filter for one of my lenses as I knew I would be doing some shooting out at the lake. The kids were in the water and I had my canon 70-300 with the filter on. When I got back to the cottage I noticed that the photos were not as sharp as usual. Would a polarizing filter cause this? The colours were perfect but the images are not good for printing.

I will admit that the filter was not an expensive one. But will that really make the difference?

Any comments would be great! Thanks
5 REPLIES 5

cicopo
Elite

Yes a filter can cause it & it's an easy thing to test. Shoot a set of photos (same subject,  same light) with & without at a few focal lengths & compare. Good polarizers generally cost over $100.

 

"A skill is developed through constant practice with a passion to improve, not bought."

Carnac
Contributor

Could be the filter, but more likely it is due to slower shutter speed (you loose from 1.5 to 2.5 stops using a polarizing filter).

 

With a telephoto lens you need to keep the shutter speed up for sharp pictures.

 

As stated above - you can test your filter out by shooting some test images from a tripod.

 

If you decide that the filter is the problem, look into quality filters from either B+W or Hoya.

 

Jim

You also didn't mention whether you got a circular or linear polarizer.  I'm no expert but a circular is a linear with an extra layer on the back to deal with the digital aspects of AF.  As a test, I tried a linear polarizer on a T4I in bright light, it did work.  I tried it in a low light setting (same filter and lens) and got poor results.  In addition to the tests noted, try one where you manually focus on something at 'infinity' with the polarizer on and see if it's in focus there.  You could be reducing the light enough that AF isn't working correctly (already noted).

The polarizer _must_ be a "circular" polarizer... not a "linear" polarizer or "top" polarizer (which is another name for linear polarizer.)

 

A circular polarizer is a linear polarizer with a quarter-wave plate on the back.  Without this, a linear polarizer makes it very difficult for a camera to achieve correct focus (it also makes it difficult for the metering system to get correct results.) 

 

 

Tim Campbell
5D III, 5D IV, 60Da

ebiggs1
Legend
Legend

"Would a polarizing filter cause this?"

 

Any or all the factors above can account for OOF or blurry (not the same!) photos. Your lens is slow to start with and sacrificing 2+/- stops is not good.
If you normally take pretty nice sharp shots, you have probably already answered your own question.

EB
EOS 1DX and 1D Mk IV and less lenses then before!
Announcements