Circular / Linear Pola Question.

[neil_r]

I used to use a Bronica medium format system and still have a Cokin P series Linear Polarising filter.

I have a 77 mm Circular polarizer that I use on a 100-400 and a 17-40 mm on an EOS 1D Mk II. I have Cokin rings that will fit on my 50mm 1.4 and my 86 mm 1.8.

I know that there is no difference in the effect that either the circular or linear filter produces, what I want to know is why Canon says Circular only. If the linear filter fools the meter then I obviously can’t use it, if however, it only fools the auto focus I can save myself a few bob and make do.

Many thanks

N

[hmhm]

The generally stated reason for requiring a circular polarizer on an SLR is that the linear polarizer is supposed to interfere with the AF mechanism. I've never heard anyone say that it effects exposure metering.

I have seen people post that they've used linear polarizers and AF worked "just fine". I dunno, I've never tried. Give it a shot and see what happens! Even if it works, I'd probably be disinclined to use it routinely.
-harry

[Hellashot]

I have read that linear polarizing filters are for an older type of camera and anything newer (several or more years older) should use circular.

Hellashot

[neil_r]

I have read that linear polarizing filters are for an older type of camera and anything newer (several or more years older) should use circular.

Hellashot

Yes, but why ??? :)

N

[tofuboy]

I'm pretty sure hmhm was right about it affecting auto focus. Here's a bit from a linear polarizers product page on b&h. I don't see any harm in using a linear polarizer, you may just need to focus manually.

Linear polarizers are used with most manual focus cameras and are not recommended for auto-focus cameras.

[DocFrankenstein]

You know how you can remove glare from a reflective surface with a linear polarizer?

I though that if you polarize the light BEFORE it hits the reflective surface (at the right angle of course), you won't get a reflection.

So, what might happen is that the viewfinder may be completely dark if you mount in an SLR and rotate it.

It's just an assumption on my part. Is this true?

[neil_r]

You know how you can remove glare from a reflective surface with a linear polarizer?

I though that if you polarize the light BEFORE it hits the reflective surface (at the right angle of course), you won't get a reflection.

So, what might happen is that the viewfinder may be completely dark if you mount in an SLR and rotate it.

It's just an assumption on my part. Is this true?


I have used both and as I said the effect is exactly the same. I just wondered if there was something going on that I don't know about and cant see.

N