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I know I used to know this but what is the difference between these two?
Thanks
Thanks
Linear vs Circular
- Thread starter antonroland
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Yes I do but why circular for digital?
What is the difference and why is Circular better for digital?
Will linear not work at all?
What is the difference and why is Circular better for digital?
Will linear not work at all?
andrewc
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there is something about the linear type which confuses the cameras metering or AF systems (AF I think). I understand the linear type to be more effective as a polariser, but the circular one is the type to choose for trouble free dSLR usage.
Garry Edwards
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Here's a brief extract from one of my tutorials.
Polarisers are used to reduce or remove reflections.
Many people wrongly believe that they work only with shiny surfaces, but in fact they work with the sky too, this helps to remove internal reflections and so increases the blue saturation of the sky.
They do not work at all with unpainted metal, and for maximum effect the lens axis should be between 30-40° to the reflecting surface. Polarisers are more effective with telephoto lenses than standard lenses, and when used with wideangle lenses the polarising effect can be very uneven.
They need to be rotated in their mounts until, looking through your SLR viewfinder, the reflections are at their minimum. If you are using a non-SLR camera just look through the filter with your eye, rotate it for maximum effect and then fit it to your camera in exactly the same relative position. The result may not be perfect but it will be fairly close.
Polarisers are available in two distinct types, circular and linear. This refers to their characteristics, not their shape! Circular polarisers are the same as linear, except that they also have a quarter-wave plate added, which increases the cost.
The results produced by the two types are similar but not identical, and there is no point in paying the extra for a circular polariser unless you need one. You need to buy a circular polariser if your camera uses a semi-silvered mirror in either the metering or autofocus system, so you'll need a circular type with nearly all SLR cameras
Polarisers are used to reduce or remove reflections.
Many people wrongly believe that they work only with shiny surfaces, but in fact they work with the sky too, this helps to remove internal reflections and so increases the blue saturation of the sky.
They do not work at all with unpainted metal, and for maximum effect the lens axis should be between 30-40° to the reflecting surface. Polarisers are more effective with telephoto lenses than standard lenses, and when used with wideangle lenses the polarising effect can be very uneven.
They need to be rotated in their mounts until, looking through your SLR viewfinder, the reflections are at their minimum. If you are using a non-SLR camera just look through the filter with your eye, rotate it for maximum effect and then fit it to your camera in exactly the same relative position. The result may not be perfect but it will be fairly close.
Polarisers are available in two distinct types, circular and linear. This refers to their characteristics, not their shape! Circular polarisers are the same as linear, except that they also have a quarter-wave plate added, which increases the cost.
The results produced by the two types are similar but not identical, and there is no point in paying the extra for a circular polariser unless you need one. You need to buy a circular polariser if your camera uses a semi-silvered mirror in either the metering or autofocus system, so you'll need a circular type with nearly all SLR cameras
Chuckurbarla
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I have both types now and this is what I find in practice:
Absolutely no difference whatsoever on my EOS350D or EOS50e!
Having said that, all the information I could find said that because the linear type polarised all the light, auto-focus slr/dslr would have trouble focusing and possibly metering. The extra quarter wave plate on a circular type is supposed to un-polarise a little of the light so that the a/f and metering work properly.
Absolutely no difference whatsoever on my EOS350D or EOS50e!
Having said that, all the information I could find said that because the linear type polarised all the light, auto-focus slr/dslr would have trouble focusing and possibly metering. The extra quarter wave plate on a circular type is supposed to un-polarise a little of the light so that the a/f and metering work properly.
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The important bit ^
Garry Edwards
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Yes, that's the relevant bit, I just thought I'd include a bit more info too
It's the optical elements in the camera that make the difference, the statement that digital cameras need circular polarising screens isn't completely wrong (because most do) but the fact that a camera happens to be digital isn't relevant. Two of my cameras will work perfectly with linear polarising screens simply because they don't have any semi-silvered mirrors. 1 takes only film, 1 takes film & digital
djaphoto
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I've dug up this old thread as I've just bought a polariser and actually got a linear whereas I thought I was getting a circular.
I own cricular already for my other lenses, but this was for my new lens. I've taken some sample shots with the linear and it appears to do a good job, should I stick with it or get a circular?
I own cricular already for my other lenses, but this was for my new lens. I've taken some sample shots with the linear and it appears to do a good job, should I stick with it or get a circular?
Gofer
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Logic dictates that if it works OK, stick with it. I made the same error when I ordered a polariser a while back and ended up with a linear for my Canon 28-135, but it has never given me any grief with regard to focus or exposure.