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Odd Request for Experiment: Advise ND Filter Gel for Plasma TV...?


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#1 Rich Harkness

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Posted 22 July 2006 - 08:52 PM

Hi folks,

This is an odd request, but I can't think of a better place to ask this question.

I do post production sound (effects) and it's been a long time since I shot film, so I need to come to you folks.

I'm always experimenting in getting better imaging with my current home display: a Panasonic plasma. We all know the importance of good black levels to an image - especially when viewing in dark conditions. The Panasonic plasma actually has quite good black levels for a plasma, but far from perfect.
The pixels must remain ignited to some degree, so even in the darkest areas they can't achieve a true black. The dark areas are left glowing a bit.

For kicks I was thinking of experimenting with neutral density filters - grabbing a sheet large enough to cover the display's image area (42" plasma). That way I might get the black levels lower. When I worked in production there were big sheets of the stuff for controlling light through windows etc.

Can you suggest which type of neutral density gel/filter would be most appropriate for this experiment? Ideally the filter would be as optically transparent as possible (good quality). And I suppose a non-reflective surface would help more (so it doesn't "shine" light off it).

Any suggestions as to what to get, and where to get it? Lighting department? Camera department? Names or brands?

Many thanks!

Rich.
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#2 Rich Harkness

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Posted 25 July 2006 - 09:26 AM

Anyone? Anyone?....Bueller?.....


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#3 G McMahon

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Posted 25 July 2006 - 11:23 AM

Hello all,

I have had a few drinks so please exuse me but i am not sure what your asking. Are you asking questions regarding shooting your plasma screen, or getting a better picture?

In my limited opinion, shooting with an ND gel over your screen would only cut down on the light coming from your screen as a whole (think of it as sunglasses), generally if a screen is in shot you want the detail registering, and unless your working around other low level fixtures why would you do that?

Graeme
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#4 Rich Harkness

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Posted 26 July 2006 - 07:14 AM

Hello all,

I have had a few drinks so please exuse me but i am not sure what your asking. Are you asking questions regarding shooting your plasma screen, or getting a better picture?

In my limited opinion, shooting with an ND gel over your screen would only cut down on the light coming from your screen as a whole (think of it as sunglasses), generally if a screen is in shot you want the detail registering, and unless your working around other low level fixtures why would you do that?

Graeme


I'm not shooting the TV - just trying to get a "better" picture by trying to lower the black levels via ND gel (or whatever).


Rich.
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#5 Phil Connolly

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Posted 26 July 2006 - 10:09 AM

Well you can get ND filters or various strengths from www.leefilters.com

They do Filter Swatch books, I would get one of those so you can try lots of different filter strengths to see if it works before buying and which strength works best.
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#6 Patrick Neary

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Posted 26 July 2006 - 10:29 AM

Hi-

The obvious problem is that the highlights and midtones would all be darkened as well.
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#7 James Steven Beverly

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Posted 26 July 2006 - 03:01 PM

You know they do make a grey polarizing glass filter that fits over CRT screens for people who are on a computer all day long and it it's designed to fit right into a computer's screen. It would probably work great for what your wanting to do. The one I have is made by Interex and is model ISP-200. It's very old but I'm sure they're still in business. I got it out and set it over my plasma screen and the blacks DO appear the be a bit richer. The advantage of having a filter designed to fit a computer screen is that is goes on and comes off very easily (Mine has an L shaped, adjustable set of blackets w/ non-slip material attached to the bottom side of the bracket that simply hooks over the monitor body so that the filter hang in front of the screen. You might consider this instead of actual ND filters OR use one of these as a frame to hold your ND filters. Just a thought B)

Edited by Capt.Video, 26 July 2006 - 03:03 PM.

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#8 Michael Nash

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Posted 26 July 2006 - 05:34 PM

I think the lightest density you're going to find on a roll is ND.3 (one stop). It would indeed make everything darker, not just the blacks, but it will be very color-neutral (that's the whole idea). The nice thing about gel on the roll is that you can apply it right onto the surface of a large screen plasma, and can trim it to fit cleanly.
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#9 Laurent Andrieux

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Posted 26 July 2006 - 06:46 PM

I think a scrim like what Capt. Video mentions would cut the reflexion a gel would not. I guess this is acually why they do this material for computers screens instead of gel. A screen is originally antiflare treated and the ND gel is not.

There is 0.15 ND gel on the market, BTW but I'm not sure it would be enough (it will cut off about 25 to 30% of the light)

As to the loss with midtones and highlights, just set your monitor afterwards, with the scrim on it, just as if there would be none. You'd certainly get deeper blacks, that you will set with the brightness control and then set your contrast so that white looks white to you... If your set allows that since it won't be able to power as much light in the highlights.

That's a big problem with plasma screens. They don't give much details in the highlight neiver...
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#10 Rich Harkness

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Posted 27 July 2006 - 09:51 PM

I appreciate the replies everyone!

Since my last post I actually got a hold of some ND gel - one and two stop. I cut it to size and tried both on the display. Yup, obviously an appreciable drop in black levels, not to mention over-all luminance. I had to pump up my plasma's contrast quite a bit - even so I could never get near the brilliance of the unfiltered image. But that extra deep black level really pays off when you need it (in dark scenes, or dark objects etc).


I used to be an electric (long ago) and egads did that gel ever remind me how much I hated working with that stuff (maybe I'm just a spaz though).

And as people have noted, the gel is unfortunately super-reflective. Definitely not very suitable as a display "tweak" under anything but very dark lighting conditions. As well, it did soften the image just a tad.


As to CaptanVideo's recomendation that sounds really cool. However, even if a piece of polarized glass big enough to cover a 42" plasma is actually made (let alone the 65" plasma I'm considering buying) it sounds extremely heavy and unwieldy.

I was just hoping that there was some ND gel I wasn't aware of that was made to higher grade quality than the usual stuff.

Thanks again everyone!

Rich.
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