Cokin Linear Polariser Filter vs Cokin Circular

[Mark101]

I have an old Cokin P160 Linear Polarising Filter which I've just attached to my Canon 40D. Now I thought a modern camera needed a circular filter because of all the reasons we are told. What I've found strange is that all the shots I've taken are perfectly exposed and in focus - How can this be?

I've played around with the filter darkening the imaged etc , but again the results are always in focus and exposed correctly.

[El_Sid]

I've never has a single problem with my linear Cokin polariser either. Indeed the only polariser that has ever given focus problems was a circular type. Set at anything other than minimum effect you couldn't focus at all...

[LargeFormat]

might there be a difference between phase detection and contrast measurement focussing?

[parisian]

I was always taught to focus first and then apply the filter effect

[Steve_F]

Hi,
I've always been led to believe that the difference between a 'Linear' & 'Circular' polariser is that if you use Auto-focus or Spot metering then you need the 'Circular' type. As a result I've only ever purchased this type.

Does this help?

Steve.

[Mark101]

Hi,
I've always been led to believe that the difference between a 'Linear' & 'Circular' polariser is that if you use Auto-focus or Spot metering then you need the 'Circular' type. As a result I've only ever purchased this type.

Does this help?

Steve.

Thanks but no, because the linear one seems to work on my 40d