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Old March 21st, 2003, 04:43 PM   #1
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Filters: ND or Polarizer

I'm a little unsure of which filter option is best for primarily outdoor, daylight filming in situations where bright sunlight creates hot spots and harsh shadows. Can somebody explain the best application for ND vs. Polarizing filters?

Michael
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Old March 21st, 2003, 05:03 PM   #2
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Neutral density filters apply a calibrated reduction in light. Their darkness is calibrated (ex: ND 6, ND 4, etc.). Reducing the brightness through the lens will enable you to open the iris and get more detail in shade and shaadow areas. Note that it will also affect your depth of focus, although not dramatically for consumer and prosumer cameras.

Polarizing filters are designed to reduce, and in many cases eliminate, glare from polarized light sources such as reflections. They collaterally have the effect of improving color saturation in many daylight scenes. Polarizers will darken your exposure, somewhat like a neutral density filter, but that is not their primary function.

Both deserve investment for outdoor shooting. If your camera is not equipped with a built-in ND filter I would invest in this first, as it provides the typical videographer a bit more flexibility shooting in bright outdoor conditions.
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Old March 21st, 2003, 07:56 PM   #3
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For video camera use a linear polarizor will do just fine. Spend the money you save on a better quality linear. A linear is almost half the price of a circular.

Remember all glass is not created equally and you do geyt what you pay for.

Tiffen (ok)
http://www.tiffen.com/Header_page_tiffen_filters.htm

Hoya (ok)
http://www.thkphoto.com/catalog/hoya.html

B+W (the very best)
http://www.schneideroptics.com/filters/filters_for_motion_picture_&_broadcast_television/

Heliopan (the very best)
http://www.hpmarketingcorp.com/heliopan.html
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Old March 22nd, 2003, 11:50 AM   #4
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Some cameras have neutral density filters built in.
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Old March 22nd, 2003, 11:54 AM   #5
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Both filters can be of value, as Ken and Bryan describe, but neither will eliminate harsh shadows caused by shooting in direct sunlight, or lower contrast from bright sunlight versus shade. You must improve the shooting environment in these situations by various methods, such as using a "silk" over your subject to eliminate the harsh shadows caused by the overhead sunlight. (If you do this, you must have a background value that compliments your subject, or it will be overexposed) Or, add a reflector to bounce sunlight into your subject to wash out the shadows (which can result in squinting). Or, move your location. There is no "magic bullet" that can solve these problems.

Additionally, be aware when using a polarizer that if you need to pan your camera your exposure can change dramatically, as the effect of the filter changes in relation to the angle to the sun.
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Old March 22nd, 2003, 06:35 PM   #6
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Polarizers and ND filters effect your exposure. They reduce the amount of light hitting the CCD. This can have a direct effect on the DOF. In no way do they effect contrast. The balance between highlights and shadows need to be balanced by other means. Do as Wayne suggests or use a graduated filter to balance between sky and foreground or highlights and shadows.
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Old March 23rd, 2003, 02:22 AM   #7
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This is a limited use situation, but it may come in handy: if you are shooting a locked-off shot that has a serious contrast issue such as backlit (sun in front of you) vista, and the action takes place below the horizon line i.e. not in front of the sky, you can bracket your exposures and do a post fix. In other words, lock your tripod and head firmly and shoot the action with the exposure set for the actors (allowing the sky to blow out), then shoot a second pass with the lens stopped down for a nice exposure on the sky. Then it's just a matter of cutting a matte between the two in your editing software. As Wayne mentioned, an ND grad will do a similar effect but if you don't have access to that or a mattebox to use it in, this may work for you.

A specialized filter that can be helpful in high contrast situation is the Tiffen Ultra-Con series, but they are a bit tricky to work with & require some testing.
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Old March 23rd, 2003, 09:27 AM   #8
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Michael

I gather you have acquired a pdx10?

On a bright sunny day in Texas a polarizer and ND8 will put you at f5.6

If you need slim DOF you will need an extra ND8 which will put you at f2.0

so 1 pol plus 2 x ND8 is recommended for flexibility

problem is the pdx10 allows only one 37mm filter behind the lens shade - if you are stacking more than one filter the shade will have to be removed.

The remedy I use on my 950 is as follows

1 get a 37mm to 49mm step ring
2 get all your filters in the 49mm size

when stacked the nature of this set up creates a lens shade through the stacked filters and thus will avoid any vignette problems when you shoot at the wide setting - especially important for the pdx10 16:9 mode

hope this helps
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Old March 23rd, 2003, 09:49 AM   #9
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Thanks

Great info, guys. This helps a ton.

Jay, you are correct that I bought a PDX10. The step ring is a great idea. I already have a set of filters for my 35mm cam that are 49mm, so that would allow me to make use of some of those filters.

Unfortunately, I'm limited in how much I can control the lighting or the "actors", since the actors are typically wildlife in a hunting situation. I can, however, control my setup in relation to the lighting source (sun) in most situations.

Thanks again for the great responses. I don't know if I've mentioned it before, but THIS SITE ROCKS! :)

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Old March 28th, 2003, 09:21 AM   #10
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ND2?

I haven't been able to find an ND8 filter, but did find a couple of ND2's. I'm not sure what the relationship between the two numbers is. Can somebody give me a crash course?

Michael
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Old March 28th, 2003, 11:32 AM   #11
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Michael,
Schneider Optics, one of the best manufacturers of filters and accessory lenses, has a very good summary of this on their site.
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Old March 28th, 2003, 12:53 PM   #12
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ND 2.0 or ND +2?

How do I tell if the filter I have, which is identified on the ring as ND2 is the ND 2.0, which is 10 stops, or more likely ND + 2 (two stops?), which according to the chart would be ND .6, right?

It's a Quantary (made by Hoya) that I picked up at the local Ritz, because I couldn't find anything else locally in 37mm, or even a step ring. I'm assuming the ND2 (10 stops) is probably more of a specialty filter, and would be very dense?

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Old March 28th, 2003, 03:07 PM   #13
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You probably have the 0.2 -- the 2.0 is very dark and not something that you're likely to find in stock at most camera stores.
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Old March 28th, 2003, 11:46 PM   #14
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Confused

I am looking at getting some ND and Polarizer filters.

I am looking at some tiffen's
.3 , .6, .9 Which will be a good one for an outside wedding in a garden? Maybe all of them?

I assume a linear polarized lens?

I don't understand the numbering on filters. Sorry to be so green.

Mark
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Old March 28th, 2003, 11:55 PM   #15
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Marc,
Re: ND filters, selection partly depends on whether or not your camera's lens already provides one (or more) built-in ND filters (such as the GL2 and some of the XL1S lenses). Since all cameras can generally handle bright sunlight conditions it will also depend on how you think you want to manage your image via your iris. Darker image = wider iris (for a given shutter speed) = slightly shallower depth of field.

A linear polarizer is generally recommended for video cameras, although a circular will also work.
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