Polarising filter

SammyC · 11-08-2005, 08:18

I read somewhere that only certain lenses can be fitted with these due to the way they focus, is this true? and if so what lens feature allows the use of said filter?

wez130 · 11-08-2005, 08:21

i don't think it's a matter of lens but lens type, see some have a fixed focus and some have a rotating focus barrel so a linear would be no good (i think) circular polarisers are fine for any type of lens though. AFAIK

11-08-2005, 09:16

The recommended type of polariser for autofocus cameras is circular.
Linear polarisers can interefere with the way AF Cameras focus, something to do with them blocking a certain type of light that the AF system uses.

I have a circular filter, and both my lenses are external focus, in that the barrel rotates the filter when it focuses.

All it requires is to set the shot up first, focus, then rotate the polariser to the desired position.

SammyC · 11-08-2005, 09:31

That'll be the answer then.

11-08-2005, 09:45

Well it's *an* answer. Not sure how correct it is

daveyuk · 11-08-2005, 09:59

I to use the circular type and have had no problems with auto or manual focus.

Hedgehog · 11-08-2005, 12:07

I've used both circular & linear on both Fuji (s602) & Canon (350D & A85) cameras with no detremental effect on the AF. On the Canons with the linear, however, you have to adjust the exposure to compensate as the metering can't cope with it (apparently it uses a type of polariser in the metering & gets confused). As far as lenses is concerned if you have a rotating front element you have to adjust the filter no matter which type it is after the camera has focused.

SammyC · 11-08-2005, 13:09

Does it make much difference then the orientation of the filter?

Hedgehog · 11-08-2005, 15:11

Yup... you'll notice that the light changes as you spin it (circular or linear).

11-08-2005, 08:18	#1 (permalink)
SammyC Forum Regular Join Date: Jul 2005 Location: Bristol Posts: 1,466	Polarising filter I read somewhere that only certain lenses can be fitted with these due to the way they focus, is this true? and if so what lens feature allows the use of said filter?

11-08-2005, 12:07	#7 (permalink)
Hedgehog New here Join Date: Jul 2005 Location: Any Pub - Derbyshire Posts: 38	I've used both circular & linear on both Fuji (s602) & Canon (350D & A85) cameras with no detremental effect on the AF. On the Canons with the linear, however, you have to adjust the exposure to compensate as the metering can't cope with it (apparently it uses a type of polariser in the metering & gets confused). As far as lenses is concerned if you have a rotating front element you have to adjust the filter no matter which type it is after the camera has focused. Last edited by Hedgehog : 11-08-2005 at 12:10.

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11-08-2005, 08:21	#2 (permalink)
wez130 Getting Comfy Join Date: Jul 2005 Posts: 136	i don't think it's a matter of lens but lens type, see some have a fixed focus and some have a rotating focus barrel so a linear would be no good (i think) circular polarisers are fine for any type of lens though. AFAIK

11-08-2005, 09:16	#3 (permalink)
Marcel Posts: n/a	The recommended type of polariser for autofocus cameras is circular. Linear polarisers can interefere with the way AF Cameras focus, something to do with them blocking a certain type of light that the AF system uses. I have a circular filter, and both my lenses are external focus, in that the barrel rotates the filter when it focuses. All it requires is to set the shot up first, focus, then rotate the polariser to the desired position.

11-08-2005, 09:31	#4 (permalink)
SammyC Forum Regular Join Date: Jul 2005 Location: Bristol Posts: 1,466	That'll be the answer then.

11-08-2005, 09:45	#5 (permalink)
Marcel Posts: n/a	Well it's an answer. Not sure how correct it is

11-08-2005, 09:59	#6 (permalink)
daveyuk Forum Regular Join Date: Jul 2005 Location: Berkshire Posts: 1,150	I to use the circular type and have had no problems with auto or manual focus.

11-08-2005, 13:09	#8 (permalink)
SammyC Forum Regular Join Date: Jul 2005 Location: Bristol Posts: 1,466	Does it make much difference then the orientation of the filter?

11-08-2005, 15:11	#9 (permalink)
Hedgehog New here Join Date: Jul 2005 Location: Any Pub - Derbyshire Posts: 38	Yup... you'll notice that the light changes as you spin it (circular or linear).