Cpl filter affect lens focus


baynald12

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Apr 30, 2010
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#1
Hi guys, anyone experienced when using cpl filter it change the focus of ur lens?
I just send my Sigma 70-300 for calibration, im very happy on the focus but yesterday when i tried using it with cpl ( a cheap one ) i got a blurred pics and even I checked on LV the subject is OOF. When I changed it back with UV filter the focus is just fine, so I suspect its because of the cpl filter. Does cheaper filters affect the lens focus?
 

Octarine

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Staff member
Jan 3, 2008
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Pasir Ris
#2
Hi guys, anyone experienced when using cpl filter it change the focus of ur lens?
I just send my Sigma 70-300 for calibration, im very happy on the focus but yesterday when i tried using it with cpl ( a cheap one ) i got a blurred pics and even I checked on LV the subject is OOF. When I changed it back with UV filter the focus is just fine, so I suspect its because of the cpl filter. Does cheaper filters affect the lens focus?
What else does it need to proof your suspicion? But it's not that your topic is new .. it's popping up every week. Welcome to the club. Get quality filters, period.
Beside this: I don't see how any lens calibration can change this. A bit wasted money, imho.
 

justin79

New Member
Dec 30, 2008
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#3
Does not matter whether the glass is cheap or not. Get a more trusted or renowned brand of CPL to test it out and convince yourself.

You do photography to convince yourself, not others. Cheers :)
 

baynald12

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Apr 30, 2010
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#4
thanks guys, I will get another cpl, a quality one.
 

ovaltinemilo

Senior Member
Sep 12, 2009
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Sin jia Po lah
#5
got pic to see? of course it's always better to invest in a reasonable CPL. but oof is abit too much..haha...
 

baynald12

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Apr 30, 2010
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#6
its really OOF, that's why my initial thought its because of the calibration but when I tried with my uv filter its fine.
maybe its what u get when u want a cheaper one. hehehe
must invest with quality filter, lesson learned.
 

arctos

New Member
Jun 2, 2008
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#7
While having quality filters does matter, I would advise you to check another 2 things:
  1. Does the front element rotate when focusing? (I'm not a Sigma user, hence I don't know and have to ask you to check.) This problem is usually more pronouced when using CPL as compared to UV filters due to the need to rotate the CPL to get the desired effect.
  2. CPLs generally reduce by 2 stops, whereas UV filters should not. Did your shutter speed decrease (causing camera shake, unless you were on tripod and using remote) when comparing the 2 photos?
Just my newbie $0.02. :)
 

baynald12

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Apr 30, 2010
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#8
While having quality filters does matter, I would advise you to check another 2 things:
  1. Does the front element rotate when focusing? (I'm not a Sigma user, hence I don't know and have to ask you to check.) This problem is usually more pronouced when using CPL as compared to UV filters due to the need to rotate the CPL to get the desired effect.
  2. CPLs generally reduce by 2 stops, whereas UV filters should not. Did your shutter speed decrease (causing camera shake, unless you were on tripod and using remote) when comparing the 2 photos?
Just my newbie $0.02. :)
Bro I used tripod and shoot the flag hanging opposite my flat, I tried to rotate the filter but still OOF.
Maybe next time I will buy CPL must bring my gadget to try.
 

arctos

New Member
Jun 2, 2008
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#9
Bro I used tripod and shoot the flag hanging opposite my flat, I tried to rotate the filter but still OOF.
Maybe next time I will buy CPL must bring my gadget to try.
Ok, tripod means camera shake due to longer exposure unlikely. But you were shooting a flag hanging outside - wind movement could make it "blur" too. :bsmilie:

Oh, and precisely coz you tried to rotate the filter, that could throw the focus off-balance if you have a rotating front element. Erm I hope someone more eloquent than me can explain this. :sweat:
 

baynald12

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Apr 30, 2010
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#10
Ok, tripod means camera shake due to longer exposure unlikely. But you were shooting a flag hanging outside - wind movement could make it "blur" too. :bsmilie:

Oh, and precisely coz you tried to rotate the filter, that could throw the focus off-balance if you have a rotating front element. Erm I hope someone more eloquent than me can explain this. :sweat:
Bro I used tripod to make sure that the blurred pics not due to my handshake.
Sony has built in SS, that's why when I shoot again w/o the cpl the pics were sharp even w/o tripod.
 

wonglp

Moderator
Staff member
Jul 20, 2007
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Bukit Batok
#11
Hi guys, anyone experienced when using cpl filter it change the focus of ur lens?
I just send my Sigma 70-300 for calibration, im very happy on the focus but yesterday when i tried using it with cpl ( a cheap one ) i got a blurred pics and even I checked on LV the subject is OOF. When I changed it back with UV filter the focus is just fine, so I suspect its because of the cpl filter. Does cheaper filters affect the lens focus?
can share what cpl brand u use?;)
 

Limsgp

New Member
Dec 16, 2005
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Singapore, Bedok
#12
Juz asking.. Are you sure it is a CPL and not PL?

Normal polariser WILL affect AF.. CPL is needed for cameras with AF..
 

Feb 16, 2008
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the blue planet
#14
i saw a CPL which does not work with Canon 55-250 IS lens..
it either off-focuses or totally fails to focus when put on..
but it works well with the 18-55 IS kit lens..
 

baynald12

Deregistered
Apr 30, 2010
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#15
Actually just bought it from someone who ads his product here at CS, made in china the brand is L-GREEN.
 

baynald12

Deregistered
Apr 30, 2010
124
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#16
Juz asking.. Are you sure it is a CPL and not PL?

Normal polariser WILL affect AF.. CPL is needed for cameras with AF..
Its says in the label that its CPL.
I tried using AF and MF and the result still OOF.
 

daredevil123

Moderator
Staff member
Oct 25, 2005
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lil red dot
#17
Its says in the label that its CPL.
I tried using AF and MF and the result still OOF.
It is probably not OOF la. Just that the pictures are generally soft.. not OOF.

Question for you: did you remove the UV/protection filter before putting on the CPL? Or did you stack the CPL over the UV filter?
 

baynald12

Deregistered
Apr 30, 2010
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#18
It is probably not OOF la. Just that the pictures are generally soft.. not OOF.

Question for you: did you remove the UV/protection filter before putting on the CPL? Or did you stack the CPL over the UV filter?
its really blurred. even i used the MF CHECK LV and zoom in the subject still OOF, the pics came out with shadows on the stars and moon. yes i removed the uv filter
 

justin79

New Member
Dec 30, 2008
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#19
Actually just bought it from someone who ads his product here at CS, made in china the brand is L-GREEN.
I have know someone that uses tat china brand filter b4 and image came out blur. Well if its down to the filter, change it. Very simple and not need to argue what else went wrong...
 

daredevil123

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Oct 25, 2005
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lil red dot
#20
its really blurred. even i used the MF CHECK LV and zoom in the subject still OOF, the pics came out with shadows on the stars and moon. yes i removed the uv filter
It is blur, and not out-of-focus.

If it is out-of-focus, you should be able to detect another object in another plane to be in focus.

You subject is in focus. But the entire picture is soft. Very different thing, OOF and blur(soft), two different concepts.

in the old days, I had a cheap uncoated Hoya UV filter, and a cheap uncoated Hoya CPL. One nice sunny day, I stacked the CPL on top of the UV and shot. The pics came up all blur. After half a day, I removed the CPL, the pics became sharp again. Here is an example:

Stacked filters:


Only UV on the same day:
 

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