Comparison of Stereo Projection Screens

By George Themelis, aka DrT - (November 2002-April 2003)

This web page summarizes the results from my Stereo Projection Screen testing that took place in two different times:

The main conclusion was that the new Da-Lite screen was 1 f-stop dimmer than the older material and (even worse in my opinion) showed two f-stops less extinction, leading to noticeable "ghosting".  None of the screens tested in the first investigation were available for sale new.

Disclaimer

I have carried out and reported this testing to the best of my abilities.  I am not receiving any compensation or benefits from any of these screen manufacturers and have absolutely no reason to favor one screen vs. another.  The results shown here are based on testing a small sample or one screen.  Variations from batch to batch are possible.  I am not responsible for purchasing decisions based on the data presented here.  I have an interest in stereo projection for my personal enjoyment.  I will be happy to discuss stereo projection issues via email.

List of Stereo Screen Manufacturers or Retailers:

Special Thanks To:

Wendy Long of Da-Lite, David Starkman and Susan Pinsky of Reel 3-D, Ron Labbe of Studio 3D, Jean-marc Henault of Trivision, and Grant Campos who supplied the Hurley and Stewart samples.  Also, many thanks to John Hart for his gentle support and encouragement to complete the testing and the many contributors of the photo-3d email list for their comments and helpful feedback.

George Themelis, drt-3d@live.com
April 2003

Summary of Results

They say that a picture is worth 1000 words.  In the pictures below I show six screen samples taped over the Da-Lite Wonderlite Material (standard to be met) and over the Marginal Da-Lite (limit of what is acceptable) for direct visual comparison of all materials.  For more pictures and 1:1 comparison, see the full report.

Comparison with Da-Lite Wonderlite (in the background)
  Brightness (bright is better) Extinction (dark is better)
Center
Off-center
(26°)
Comparison with Marginal Da-Lite (in the background)
  Brightness (bright is better) Extinction (dark is better)
Center
Off-center
(26°)

The results are summarized in the following Table:

No Subjective
Rating		 Screen Comments
6 B Da-Lite Wonderlite

Excellent Brightness and Extinction on and off center.  Not in production - used for comparison purposes (standard to match)
7 D Marginal Da-Lite Marginal Brightness & Extinction - not produced currently but used for comparison purposes (limit of what is acceptable)
9 C New Da-Lite Good On Center brightness & Extinction - brightness drops off center
10 B Reel 3-D Good Extinction on and off center.  Better off-center brightness
11 C Studio 3D A bit less brightness and extinction overall
12 B+ Trivision Better brightness & good extinction
13 C Hurley Silver Glo Bright but less extinction on and off center
14 D Hurley Silver Lenticular Less brightness & extinction, similar to Marginal Da-Lite
15 A Stewart Silver 3D Better brightness and best extinction from all screens

Comparison of Stereo Screens Not Available New

George Themelis, November 2002

I recently borrowed the new Da-Lite screen (with "Silver Matte" finish) which is 8 feet wide. A quick test during our recent club meeting showed that this screen is not as bright as the older Da-Lite screen (which is using the Wonderlite material). While using this screen it was rather obvious that "ghosting" was worse than usual. So I decided to investigate. I collected 8 screens, measured their brightness and extinction, and documented their texture. The results are summarized below. Some things to note:

  1. A good screen is a screen that shows high brightness and high extinction. From these two properties, in my opinion extinction is more important. If the extinction is low then "ghosting" becomes a problem. According to Ferwerda, 6 f-stops is the minimum extinction for a screen to be suitable for stereo.

  2. A quick way to compare two screens visually: Put them next to each other, partially overlapping, and turn the projector on (both lamps). Look at them and compare the brightness. Then turn one lamp off, take a piece of polarizing material (viewing glasses are OK), orient the glasses to achieve maximum extinction and compare them again. The darker screen shows the highest extinction.

  3. To construct the Table below I have used a digital light meter to measure light intensities. All the values are in f-stops. A difference of one f-stop means twice (or half) the amount of light.

 

Screen Type

Texture

Brightness

Extinction

1

Da-Lite VIP 50"

0.5

7.5

2

AMC 50"

-0.2

6.2

3

Montgomery Ward, 40"

0

7.3

4

Knox Panorama, 40"

0

6.5

5

New Da-Lite 96"
8 foot wide made from new material Silver Matte

-0.7

5.4

6

Original Da-Lite 72"
This is the traditional Wonderlite material (now discontinued) it belongs to our stereo club.

0

7.2

7

My Da-Lite 72"
I bought this after I heard that Da-Lite was discontinuing their Wonderlite material. I did not realize that this was different until now.

-0.4

6.3

8

Da-Lite Silver Lite 40"

0.1

6.7

These results are plotted below:

Summary of Observations:

  1. Curiously, the data points follow a trend: Brighter screens also show better (higher) extinction. A good screen must be high in the upper right corner.
  2. From the 8 screens tested the best screen is no. 1 which is brightest and shows the higher extinction. The worse screen is no. 5 (new Da-Lite Silver Matte material) which shows the least brightness (one f-stop less that a good screen) and the least extinction (two f-stops less than a good screen). This is the only screen that does not meet Ferwerda's minimum 6 f-stops extinction.
  3. Most screens (1, 2, 3, 8) have a coarse lenticular texture (I measured ridges per inch - the line marker is one inch). The Wonderlite Da-Lite material (Club's screen, 6) shows a less coarse texture (about 44 ridges per inch). "My" Da-Lite screen shows a different pattern, similar to the Knox Panorama screen (4). Finally, the new Da-Lite screen shows a very different texture, the least intense than any other screen. Clearly, texture is a factor in the performance of a screen, but not the only factor because screens with apparently similar textures can have different characteristics (compare screens 1 and 2).

Conclusion: It is best to avoid the new Da-Lite screen even though the 8 feet width is very attractive. "My screen" (7) was made after the Wonderlite material ran out. It is not as good as the Wonderlite but still better than the Silver Matte. It appears that Da-Lite is moving in the wrong direction. Perhaps we should put some pressure to improve their material? Reel 3-D (www.reel3d.com) has 72" screens in stock and I am told that they are as good as the original Da-Lite Wonderlite material.

Comparison of currently AVAILABLE Stereo Screens

George Themelis, April 2003

Testing was visual and the results are shown below.  A small sample (about 8x10 inches) of the screen being tested was taped over a Da-Lite Wonderlite screen.  Four pictures were taken: 

  1. On axis of reflected light to measure comparative brightness (Bright is good)

  2. On axis of cross-polarized light to measure extinction (Dark is good)

  3. Off axis of reflected light (26°, distance away from center = 1/2 distance to the screen)

  4. Off axis of cross-polarized light

The Da-Lite Wonderlite screen was picked for the comparison because this screen represents a proven performer.  I would be extremely happy to own a screen with similar characteristics.  Both the large NSA and PSA screens are made of this material.  Note: For the subjective ratings below, this screen is rated B.

The results are shown below, together with a picture of the texture of the screen.  A summary of the results and comments follows.  Overall, I would say that the Stewart screen appears to be the best, followed by the Trivision and the Reel 3-D screen.  The "improved" Da-Lite screen is considerably improved (compared to the no. 5 screen in the previous study.  Still it is a bit behind the Wonderlite screen in that the brightness drops off center.  Extinction (which in my opinion is more important) remains good on and off center.

Screen Center (top row) - Off Center (bottom Row)
Brightness (bright is better) Extinction (Dark is better)
9 - NEW DA-LITE

Good center brightness and extinction.

Brightness falls off center.

Extinction remains good.

Subjective Rating: C
A bit worse than Wonderlite, mainly because of drop of brightness off center, but much better than the material tested earlier!
10 - REEL 3-D

Good center brightness.

Better off-center brightness (due to lenticular texture)

Good on and off-center extinction.

Subjective Rating: B
As good as Wonderlite with extra benefit of increased off-center brightness
11 - STUDIO 3D

A bit dimmer both on and off center

Good extinction on and off center

Subjective Rating: C
A bit worse than Wonderlite due to lower brightness
12 - TRIVISION

Better center and off center brightness - some tendency for hot spots

Good center and better off-center extinction

Subjective Rating: B+
Marginally better than Wonderlite due to extra brightness
14 - HURLEY GLO

Brighter on and off center

Worse extinction on and off center

Subjective Rating: C
Good brightness but extinction does not match Wonderlite
14 - HURLEY SILVER LENTICULAR

Dimmer on and off center

Worse extinction on and off center

Subjective Rating: D
Less bright and less extinction than Wonderlite
15 - STEWART SILVER 3D

Brighter on and off center

Better extinction on and off center (best extinction of all screens!)

Subjective Rating: A
Better than Wonderlite in both brightness and extinction
Brighter
Better Extinction

Brighter
Better Extinction

Subjective Ratings

About the ratings:  Anything with a rating from A to D can be used for stereo projection in my opinion.  The rating of D is given to the Da-Lite screen no. 7 in the previous study.  When I used this screen, I did not notice any difference in brightness but I became aware of a bit more ghosting than usual.  To show the difference between A and D, I put the two Da-Lite screens next to each other and took the pictures below. The Wonderlite screen (no. 6 in previous study) is on the left while screen no. 7 ("My Da-Lite) on the right.  It is clear that the Wonderlite screen is brighter and shows better extinction. 

Brightness (Bright is better) Extinction (dark is better)

Given that the Wonderlite material is a proven performer and gets a rating of B, anything with a rating of B and higher is highly recommended.  Rating of C is acceptable.  D is the limit of acceptability. 

Screen Orientation

Occasionally people wonder if the screen is oriented correctly for best performance.  Only if the screen shows some directionality in the texture, orientation is important.  Most screens do not show such directionality.  For those that do show directionality, I found that it is only the brightness off-center that is affected (not the extinction).  Consider the Reel 3-D screen that shows coarse lenticular texture.  With the lines oriented horizontally, the screen is considerably dimmer than when oriented the other way, but only when looking at the screen off center:

  Lines vertically Lines Horizontally
On Center
Off Center