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07/27/2004 12:45:14 AM · #1 |
Hi all..
I was hoping someone could explain the difference between a circular and linear polarising filter. How do they differ? Do they operate differently?
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07/27/2004 12:50:08 AM · #2 |
I don't know about exactly how they work, but I read somewhere that for digital cameras circulars are recommended, because linear mess with AF. But why exactly and how they work I don't know.
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07/27/2004 01:00:43 AM · #3 |
Try here
All I can gather is circular polarisers are designed for auto focus cameras.
Message edited by author 2004-07-27 01:12:41.
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07/27/2004 01:08:52 AM · #4 |
yeah ive read that if you use Auto focus, you need to have a circular polarizer. Also, Circular polarizers work better on lenses that have rotating front ends when focusing...
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07/27/2004 01:10:04 AM · #5 |
go circular. ijust got a filter kit with one & its great! you can adjust the intensity & stuff. check out bhphoto. got a good deal
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07/27/2004 02:12:07 AM · #6 |
Remember that you have to rotate it to get the correct effect.
Using circular polariser. Really brings out the colors on a rare S.F. sunny day :)
Message edited by author 2004-07-27 02:13:37. |
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07/27/2004 02:35:03 AM · #7 |
It depends on the type of autofocus system which polariser you need. I will look up some further info, but already know for sure that any non-DSLR can do with a linear polariser. Also any DSLR that uses contrast detection as AF can do with a linear.
And circular and linear to the user both work exactly the same, you have to turn them to vary the strength of the polarising effect. Also the angle to the sun makes a big difference.
edit : found a good description here on dpreview
so if you have a DSLR, check you manual, or buy a circular if you want to be sure.
Message edited by author 2004-07-27 02:49:39.
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07/27/2004 02:53:42 AM · #8 |
My "other" camera would NOT focus with a linear (tried it at the store, because I did not believe it), and that was a non DSLR-Nikon 5700. read alot of things after that basically said something to the effect that the linear somehow blocks too much of the "focus" field, concerning the way the camera reads the contrasts to get the auto focus (?) But what do I know? (C:
CIrcular works great with it. Suggest reading up and looking for the info for YOUR camera. Best way to do it.
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07/27/2004 03:08:25 AM · #9 |
| If you use an SLR get a circular polarizer. It all depends on how the autofocus works. a normal polarizer (the linear sort) removes one component of the light. Since an SLR uses passive focussing (it does not fire any beam, just reads the data coming in) and most SLR mirrors (that bounce the light to the metering and focussing sensors) are mostly polarizing too, the focussing and metering will not work well since you might get black spots on the sensors (if you remove both components of light, you get no light at all) depending on certain angles. A circular polarized retards the incoming light by 1/4 cycle resulting on proper polarized light for the focussing screen even though on the sensor/film it still results in properly polarized light. |
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07/27/2004 04:55:30 AM · #10 |
| It's been a while since I studied up on this but the line separating circular vs linear is not DSLR vs non-DSLR. It has to do with what type of auto focus system your cam has. Many non-DSLRs need circular. |
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07/27/2004 05:04:37 AM · #11 |
I have a linar polarizer for my Minolta Dimage7i and one for the Digital Rebel. I've never had any problems focusing or with image quality. I know that circulars are the recommended ones, but they are pretty expensive, and in my case, why get a circular when the linears I already have work fine?
June
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