Circular polarizer with the Sony EX-3
 

Hello,

I´m searching for a circular polarizer (size 4x4) for my Sony EX-3. (I use the Vocas MB-250 rail matte box.) If you have experiences to share and brands to recommend, please do. Thanks.

-terje

Try these guys Lee Filters Polariser
Steve

Schneider Optics Tru pol... excellent filter.
Regards
Gareth

Why spend more on the circular when the linear does the same job? Or do the beam-splitting CMOS block prisms polarise the light in their own way?

Thank you, gentlemen! Just keep the input coming!

Tom, I do a lot of photography and I presume that a digital video camera is quite "similar"
to a photo camera in the way light is measured. Due to my lack of language knowledgde
I´ve borrowed a few lines from Mr. Michael Reichmann of The Luminous Landscape to explain the reason why I seek a circular polarizer:

"Linear polarizers are more effective and less expensive than circular ones. But circular polarizers are needed with just about any camera that has a through-the-lens metering system, or autofocus.
The reason for this is that both of these systems use semi-silvered mirrors to siphon off some of the light coming though the lens. If that light is linearly polarized it renders either the metering or the autofocus ineffective. This means that you're going to have to buy circular polarizers unless you're shooting with a pre-1970's camera, or a view camera."

Please correct me if this information isn´t valid when it comes to digital video.

-terje

All HDV cameras do not have a prism that is used to assist auto focus. Therefore, a linear polarizer is all you need. Still photography is another matter. You can buy holders from Cokin And LEE that are meant to use their resin gels which can be modified with a part that they sell so that you can put your 4x4 on your still camera. At that point you would want a circular. But otherwise, you just need a linear for video use only.

Ryan Avery
Schneider Optics

Thanks for the expertise Ryan, I had a feeling that was the case but nice to have it confirmed. Sure saves a bit of money and widens the choice of pola available. It's not something I'd looked into myself as I never shoot auto anything anyway.
Steve

Thank you, Ryan, for your input. Maybe you could elaborate on the type of polarizing filter glass types that are out there? Formatt refer to HD glass, and I see that Schneider use something called Water White Glass, and other brand use different types of mixed function/glass filters. The use of impressive filter descriptions makes it almost bewildering to pick a product. Special products like this is hard to come by and test, at least where I live. The only option is to order the product and hope for the best. (Screw on/thread filters are of course much easier to find, but they aren´t very practical to use on the EX-3 (with a matte box).

By the way, isn´t there anything to gain at all by using a circular polarizer on the EX-3 (other that it´s possible to share the filter with my Canon 5D, of course)?

Thanks for you help.

-terje

Michael Reichmann's right in that it's the semi-silvered mirrors that cause metering systems to falter, and the Canon Pellix 35 mm SLR of the very early 70s was the first camera (with its fixed pentaprism mirror) to require a circular polarizer. He's talking SLRs of course.

Since then however circulars have been sold to wavering photographers when linears would have done nicely - and for a lot less money. As DV cams generally don't use semi-silvered mirrors to duct light off for metering and autofocus (it's generally done with the green chip), linear filters should work just fine.

It would be good to test before you buy though Terje. And please do report back.

As 4x4 filters go I can't find a whole lot of difference in prices, especially as most of the main companies offer 4x4 filter kits. I got a 4 filter Schneider kit in Paris for just over the price of 2 individual filters, all n a padded pouch.
I think these filters are in the long run, even if dearer far more practical for video than the screw on ones.
I use a Z1 at present but am looking at other cameras the EX1 for example which doesn't have the same thread...
That said I don't think I looked to see which type of filter it was when I bought the set...works fine though
Gareth

Terje,

The names are all basically marketing hoopla. There are real differences in the products though. Some companies use soda lime "green" glass which looks; green. That is no good for HD use. Some companies call their filters HD and but that is just marketing so people will think HD and associate that with their camera. That is not to say that it isn't usable but I wouldn't buy based on that.

We use the finest water white Schott glass which comes from Germany. We have the finest precision of any filter on the market and stand behind our product. We have the most effective Polarizer on the market. Actually, we started our brand solely on a clear filter and a polarizer. I will let the product and users thereof speak for themselves but I can guarantee you will be happy with a Schneider Filter. Other manufacturers reps present on DVINFO can speak for thier products.

Nothing noticeable will be gained by using a circular polarizer on your EX camera; of course you do gain the SLR functionality.

Ryan Avery
Schneider Optics

Thanks for elaborating, Ryan! I´ll check out the Schneider filter range for sure.
Linear polarizer is what I´m going for. I´ll let you know how it goes.

Best,
-terje

On the subject of a polarizer, can anyone recommend this filter on the Ex-3 when not using a matte box? That is, on the standard lens also.

So it would be a standard 77mm round polarizer?

Sorry Ryan but (unless there's a difference between the optics on the EX3 and EX1) I beg to differ, and so does George Strother:

"Tested the Schneider circular Tru-Pol. Rotation makes no measurable color shift. White balance shifts about 3% toward cyan when mounting the filter. Need to re-white when the filter goes on or off. Panning with the circular does not color shift.

Tested a Tiffen linear polarizer. 90 degree rotation gives a 30% shift magenta to green! Optimize the polarization, white balance and pan 90 degrees can give a 30% green shift. Not good. Mounting it backwards made no improvement.

Neither filter blocked the auto focus system.

It doesn't take scopes and test charts to see this color shift. Just watch on the LCD screen as you rotate the filter or make a long pan in sunlight. Maybe someone can test other brands of circular polarizers and post here."

My tests concur with George's findings. We both have the EX1 and the poster has an EX3. However, I see no reason to assume a difference.

Here are 2 test shots I did today. The www.kilby.tv/linear.wmv example was shot with a Formatt brand 4x4 in a mattebox. The www.kilby.tv/circular.wmv example was shot through a Hoya brand screw-in circular polarizer. Light source was 3200K and white balance was 3200K. Note the neutral gray wall in each case (this is my studio and the paint color was chosen to be neutral). Light green apple. Yellow lemon. Red and green Christmas treats. In the linear example, watch the color cast go from green to magenta and back. In the circular example, no shift.

Thanks for the opinion and tests. From a science aspect there is nothing to be gained in terms of polarization using a linear versus a circular polarizer. Color shift apparently is an issue with this camera. Your tests are the first I have ever heard of color shift caused by a polarizer with this camera. I have seen it with other cameras but on a limited basis. A good white balance is always recommended for most shooting situations but of course color filters (warming for example) require white balance before use. As we are all learning, the EX series of cameras seem to all have thier own little quirks that we need to adjust.



Ryan Avery
Schneider Optics