Linear & Circular polarizer

[N&D Taylor]

Can somebody please tell me the difference between linear and circular polarizer filter? Is it true that for digital camera(S404) I can just use the linear filter and get the same result?

 

[Neil Jenkins]

My understanding is that you need a circular one becuase of the way the auto focus on some cameras works. It may have nothing to do with the fact the camera is digital, but the fact it has autofocus.

The difference between them is presumably that the grid is in a circular pattern rather than straight.

Can somebody please tell me the difference between linear and
circular polarizer filter? Is it true that for digital camera(S404)
I can just use the linear filter and get the same result?

 

[Andy62252]

Can somebody please tell me the difference between linear and
circular polarizer filter? Is it true that for digital camera(S404)
I can just use the linear filter and get the same result?

I don't know about the S404, but the Dimage 7 can definately use Linear polarisers. If you get a good one the quality should be the same and give the same results, but the price will be significantly lower.

Andy

 

[theswede #100093]

My understanding is that you need a circular one becuase of the way
the auto focus on some cameras works. It may have nothing to do
with the fact the camera is digital, but the fact it has autofocus.

No. Circular is needed when the camera uses beam split technology and similar optical tricks. SLR's with autofocus usually use a beam split type of autofocus known as phase detection; this requires circular polarizing filters to work. A linear filter will render the phase detection AF inoperable while in front of the lens.

For normal contrast based AF both circular and linear will work fine. No, your friendly salesperson will not agree. No, your friendly salesperson has no clue. (S)he just wants to sell you a circular because they are more expensive.

The difference between them is presumably that the grid is in a
circular pattern rather than straight.

No. They're identical, except a circular filter has a second filter layer after the polarizing that "re-scrambles" the light withotu affecting the polarizing effect. Thus, the light will be polarized, then re-scattered so that beam split trick work.

This means that a circular filter is more complicated and more expensive. If you can find a good, multicoated linear then get that; it will be cheaper and better.

--
Jesper

 

[theswede #100093]

I don't know about the S404, but the Dimage 7 can definately use
Linear polarisers. If you get a good one the quality should be the
same and give the same results, but the price will be significantly
lower.

Correct. Any camera that does not play tricks with light, such as phase detection AF and the like (in essence, all non-SLR cameras) can use a linear polarizing filter.

--
Jesper