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Category: New Questions

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Photography Question 
Sachin 

member since: 8/10/2004
 

Circular Polarizer - What's Going On?


I tried using the CPL and didn't quite get the results as expected. On the other hand, I found that most of my pictures taken with this filter are not sharp. What could be the problem?
Sachin, China

10/6/2004 1:15:59 AM

 
Andy 
BetterPhoto Member

member since: 5/28/2002
  Try this on a sunny day: Put the polarizer on your lens, look through the viewfinder, and slowly turn 360 degrees. You will notice at some degree the sky is bluer, usually at 90 degrees between the light source and where your camera is pointing to. Now find the spot with the bluest sky, slowly turn the outer ring of the polarizer. You will notice the amount of polarization is different as you turn. So next time you know how to find the most effective angle and amount of polarization when you take picture next time. Of course, it won't turn a grey sky to blue. It also helps eliminate glare and reflection off NON-METAL subjects. Again, the angle and amount of polarization varies.
Since putting the polarizer on the lens causes the view in the viewfinder to look darker, it may be hard to focus (if your camera is not automatic focus). One way is to focus on the subject, then put on the polarizer. If this is not the problem, it may be the quality of the polarizer or foreign substances on the polarizer that cause the unsharpness.
Hope this helps.

10/6/2004 6:49:17 AM

 
Scott Pedersen

member since: 11/18/2001
  You loose at least two stops with a cpl. So assuming that you are hand holding the camera that could be the cause of your photo's not as sharp.

10/12/2004 3:55:08 AM

 
Anette Linnea Rasmussen
BetterPhoto Member

member since: 8/31/2003
  You normally use circular filter with F 2,8. That gives the best result. It is
best not to zoom.

Kind regards
Linnea

10/12/2004 11:03:28 AM

 
Sachin 

member since: 8/10/2004
  Hi everybody,

Thanks your answers. But I found something very unusuall about this. I found that every time I turned the outer ring of the CPL and half pressed the shutter release button, the camera adjusted its focus. This means everytime I turn the CPL my focus actually changed and this is very strange. Is it normall or is it not?
Usually if the camera has focused once there will be no re-focusing if I half press the shutter release.

10/12/2004 9:31:22 PM

 
Scott Pedersen

member since: 11/18/2001
  Well, I don't know as I use a maual focus camera. But it does make sense as the view is lighter/darker as you turn the ring. Try refocusing it and see if that solves the problem. You can use a CPL at any f-stop however as I pointed out you loose two stops on the shutter you do have to watch out for the speed getting too slow to handhold. In that case you can use a wider apature or a tripod or take it off.

10/14/2004 4:06:27 AM

 

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