or Connect
AVS › AVS Forum › Display Devices › Screens › DIY Screen Section › DIY black screen tests
New Posts  All Forums:Forum Nav:

DIY black screen tests - Page 6

post #151 of 350
Great info. I've read every word of this thread twice now.
post #152 of 350
What material are you using now for the reflective layer? Is it available to consumers?
post #153 of 350
Quote:
Originally Posted by New Design View Post

I am told no but I haven't tried it myself. I don't care about 3d movies at all. Most 3d set-ups at home use active 3d designs which work on any screen. Active 3d always looks really dark to me and people with less powerful projectors find that to be a huge issue. For that type of user, all they need is extra gain and a good smooth surface.

One of the manufacturers who I bought diffuser film from, specifically called out that it doesn't interfere with polarized light. like I said though, I haven't tested that personally and also, I don't know if that applies to all diffusers or just their diffusers. I can't see any reason why their ones are special though. If you test it and find out, please let us know. My bet is that it will work without any issues.

Usually it does, most diffuser films will de-polarize a large portion of the light passing through it, making it incompatible with a polarized light based 3D system. Any light bouncing back from the top of the difuser without passing through is also always de-polarized (you need a metal surface to prevent de-polarization). I've been looking for some foil to try this with, but so far I've been unable to find a foil that is said to be polarized light compatible.
post #154 of 350
Quote:
Originally Posted by staindrocks View Post

Did this thread die out or what?

Is there anybody who PM'd New Design about what specific materials, and more importantly, links to where they can be ordered? I'd really like to give this build a shot, but i don't have the extra cash and/or time to experiment with different materials myself. Since New Design has already done plenty of testing and narrowing down of which combinations give the best result, as evidenced by his completed black screen hanging on his wall, i just need to know his specific layer by layer material list for the build.

If nothing else, i'd at least like to know exactly what he used for his diffuser layer and his "charcoal rear projection material" layer. For these two elements i'd rather buy exactly what he's using than order 20 different samples of each and figure it out on my own, so a specific brand and/or link to each would be extremely helpful.

I've tried PM'ing New Design myself, but it doesn't look like he's even visited the avs forums for over two weeks, so i'm hoping someone here got the relevant info from him in earlier PM's.

I have but no answer yet! Searching for this stuff on ebay is confusing to say the least! I think all of us would appreciate some help from TS :) Due to specific rules here on avs you're not allowed to link directly here in this thread, but examples of what to search for would be great! If I search for charcoal film I get thousands of hits, would take ages to go threw them all!

 

Also, it helps a lot if you know what these films are normally used for.

 

Regards

/Pat

post #155 of 350
Quote:
Originally Posted by Future Cinema View Post

Due to specific rules here on avs you're not allowed to link directly here in this thread

Actually, according to MississippiMan (who's spent much more time in these build threads than just about anybody), not only are you allowed to post links to the materials required for a build, but it's expected when you open a build thread.


Here's his post from page 2 (over three months ago on 9/17/2013) of this very thread , directed at New Design after his resignations about breaking forum rules:
Quote:
Originally Posted by MississippiMan View Post

As for posting links to suppliers of materials for DIY projects, that is both a given requirement to allow others to follow suit, as well as something that is done all the time, as evidenced by the build threads on here. Over the years, only the posting of Mfg Screen products, or links to sites that are dedicated toward selling such have not been allowed.

So your good to go, and there is no reason to delay once your of a mind to do so. In fact, too long a hesitation after one shows really positive results usually starts to grind on everyone's nerves! eek.gif.

Unfortunately, i'm beginning to think New Design has no intention to reveal his sources for the specific materials he used in his build. He's been asked numerous times in this thread, sent multiple PM's from several members following this thread, and nobody i've contacted(i've PM'd several other members in this thread) has received responses back from New Design. The weird thing is that he keeps promising to get back to members who've sent him PM's to share the relevant info, but several weeks, even months later, still nothing. It's not looking good for us!

I guess somebody is going to have to spend the time and money to redo the material research that New Design has already done for himself here, and then open their own build thread to actually share the results AND how to duplicate the build with fellow AVS members. I've already ordered some materials, but they are just wild guesses as to what New Design used for his finished screen, so i guess i'm already $150 worth of committed to this build. It's very frustrating to know that this build cost probably just quadrupled for me compared to what it should've cost with a proper material list, and with no guarantee to even replicate New Design's apparent success with his finished screen.

My last plea to ANYONE who has actually received info back from New Design on what specific materials he used for each layer... if such a person exists, can you please PM me with the relevant info and/or links. Thanks.
post #156 of 350
He just mentioned he was making a commercial screen now, so I would imagine he is not going to release any more detailed info .
Future Cinema has given enough info for someone who really wants to experiment to go ahead and try to make one though .
It will be interesting to see the direction this one goes.
post #157 of 350
Wow, I just looked at his YouTube channel and he posted an interesting video showing his black screen material vs charcoal... http://www.youtube.com/watch?v=GzIFcZ6LSsk

Full lighting in the room too. Looked pretty impressive.
post #158 of 350
Ok. having gone through this thread i am completely sprung on this screen. I have been thinking of a black screen solution for ever. Now I gather he is planning on making a commercial screen. fair enough, hopefully he doesnt do what everyone else does and prices it out of our bugdets.

Being able to spend $300 on enough of this pure act of fabric wizardry to make a 100" diag screen will be a God send. And he will probably sell it t every single member of this forum.

Or has he been kidnapped by the folks at Bla......errr, reputable black screen makers and disposed of?eek.gif
post #159 of 350

I've read through the thread several times and here's my attempt at a materials list.  Obviously this isn't exactly what the OP used but the items should be close based on his comments.   Some of the items come in only 4 foot (48 inch) widths which limits you to a 98 inch (16:9) or 124 inch (2.35) diagonal.   So these materials may not work for you.

 

1.  The OP recommended a rigid backboard or frame as the foundation.   He used foam board...I assume the kind you find at any home supply store.   You can also create a wood frame.

 

http://www.lowes.com/pd_15355-1278-3/4X48X96+R-TECH_0__?productId=50100626&Ntt=foam+board&pl=1&currentURL=%3FNtt%3Dfoam%2Bboard&facetInfo=

 

$12

 

2.  The next layer is the reflective layer.  The OP used mylar for his rigid frame setup but said that Orcagrow (a hydroponics product) would also work well.   The orca is an interesting product in my opinion and claims a higher actual reflectivity than mylar but with no hot spotting.

 

Mylar:  

 

http://www.ebay.com/itm/Reflective-Mylar-Film-100ft-roll-4-3mil-/281034877526?pt=US_Hydroponics&var=&hash=item416efbea56

 

$60 for 48"X100 foot 4.3 mil.  Another one at 2mil is only $14 with an additional poly backing (48"x25 foot):

 

http://www.ebay.com/itm/MYLAR-GROW-ROOM-LINER-Hydroponic-Reflective-Mirror-Film-Shiny-B-W-Poly-/120926245135?pt=US_Hydroponics&var=&hash=item1c27c4110f

 

OrcaGrow:

 

(Info)  http://www.orcagrowfilm.com/Articles.asp?ID=151

 

Purchase:  http://www.hydroponics.net/i/136312

 

$46 - 54" x 25 foot

 

3.  The next layer is the black layer.   The OP said he used a rear projection material.  I couldn't find this in the right sizes.  He also said that window tinting would work.   There are three main types of window tinting:  Dyed (cheapest), metallic (too reflective - should not use), and ceramic.   Ceramic isn't as reflective but the ceramics are mostly used for heat and UV blocking so don't seem needed for this application.   I choose to find regular dyed tints:

 

This one is 20% VLT (dark) $99 60" x 25':

 

http://www.ebay.com/itm/WINDOW-TINT-FILM-60-ROLLS-DIY-AUTO-CAR-RESIDENTIAL-BUSINESS-MARINE-DIY-SAVE-/350693699941?var=620092183806&_trksid=p2054897.l4276

 

also ($60 - 60"x10 foot):

 

http://www.ebay.com/itm/Tint-Film-Roll-60-X10ft-Professional-Tinting-Window-20-VLT-2-PLY-/171093747415?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item27d5fb66d7

 

The same seller on ebay has a lot of options.

 

Also 35% VLT.   This was more expensive since I couldn't find it in the right width at less than 100 feet rolls.  60"x100 foot, $140:

 

http://www.ebay.com/itm/High-Performance-Tint-Film-2-PLY-Roll-60-X100ft-Window-Tinting-35-VLT-/171100542162?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item27d66314d2

 

The choice of VLT level seemed to be based on projector brightness.  Darker is better for excellent blacks but you need a bright projector to overcome the inherent light loss.   Also the OP noted at there was a large amount of variability between manufacturers in this area.

 

4.   Diffuser layer.   The OP had pictures of two types of diffusers...one was a fabric looking thing, maybe a silk screen type of material from the t-shirt printing industry.  The second, which he settled on was a flexible PVC film material that was opaque unless pressed against a backing (which is what we would be doing).   The most like material for this was some sort of privacy window film like this:

 

$26 - 60" x 20 foot roll

http://www.ebay.com/itm/Home-Decorative-Privacy-Frosted-Film-60-x-10-feet-Bedroom-Bathroom-Glass-/181204411731?pt=US_Window_Film&hash=item2a309fe553

 

The benefit of this over fabric is cleaning ability and possibly a sharper picture due to no weave.   Fabric would be slightly cheaper though.

 

All layers were stretched tight and attached to the foam board with staples.

 

Using the cheapest options, all this comes to just over $100 + plus shipping and taxes.   So maybe $175 total.

 

My utmost thanks to New Designs the OP for taking the time to experiment and post his results.   Please correct anything that may be wrong.

post #160 of 350

Accidentally double posted, please remove this post.

 

Regards

/Patrik


Edited by Future Cinema - 1/1/14 at 2:46pm
post #161 of 350
Quote:
Originally Posted by sodaboy581 View Post

Wow, I just looked at his YouTube channel and he posted an interesting video showing his black screen material vs charcoal... http://www.youtube.com/watch?v=GzIFcZ6LSsk

Full lighting in the room too. Looked pretty impressive.

 

That looks impressive! I guess he's using this material in his video > 

Quote:
Originally Posted by New Design View Post


 

 

...but I don't get it, thought he already was using charcoal tint when he made this sample above? What am I missing?

 

Quote:
Originally Posted by ogpedxing View Post
 

I've read through the thread several times and here's my attempt at a materials list.  Obviously this isn't exactly what the OP used but the items should be close based on his comments.   Some of the items come in only 4 foot (48 inch) widths which limits you to a 98 inch (16:9) or 124 inch (2.35) diagonal.   So these materials may not work for you.

 

1.  The OP recommended a rigid backboard or frame as the foundation.   He used foam board...I assume the kind you find at any home supply store.   You can also create a wood frame.

 

http://www.lowes.com/pd_15355-1278-3/4X48X96+R-TECH_0__?productId=50100626&Ntt=foam+board&pl=1&currentURL=%3FNtt%3Dfoam%2Bboard&facetInfo=

 

$12

 

2.  The next layer is the reflective layer.  The OP used mylar for his rigid frame setup but said that Orcagrow (a hydroponics product) would also work well.   The orca is an interesting product in my opinion and claims a higher actual reflectivity than mylar but with no hot spotting.

 

Mylar:  

 

http://www.ebay.com/itm/Reflective-Mylar-Film-100ft-roll-4-3mil-/281034877526?pt=US_Hydroponics&var=&hash=item416efbea56

 

$60 for 48"X100 foot 4.3 mil.  Another one at 2mil is only $14 with an additional poly backing (48"x25 foot):

 

http://www.ebay.com/itm/MYLAR-GROW-ROOM-LINER-Hydroponic-Reflective-Mirror-Film-Shiny-B-W-Poly-/120926245135?pt=US_Hydroponics&var=&hash=item1c27c4110f

 

OrcaGrow:

 

(Info)  http://www.orcagrowfilm.com/Articles.asp?ID=151

 

Purchase:  http://www.hydroponics.net/i/136312

 

$46 - 54" x 25 foot

 

3.  The next layer is the black layer.   The OP said he used a rear projection material.  I couldn't find this in the right sizes.  He also said that window tinting would work.   There are three main types of window tinting:  Dyed (cheapest), metallic (too reflective - should not use), and ceramic.   Ceramic isn't as reflective but the ceramics are mostly used for heat and UV blocking so don't seem needed for this application.   I choose to find regular dyed tints:

 

This one is 20% VLT (dark) $99 60" x 25':

 

http://www.ebay.com/itm/WINDOW-TINT-FILM-60-ROLLS-DIY-AUTO-CAR-RESIDENTIAL-BUSINESS-MARINE-DIY-SAVE-/350693699941?var=620092183806&_trksid=p2054897.l4276

 

also ($60 - 60"x10 foot):

 

http://www.ebay.com/itm/Tint-Film-Roll-60-X10ft-Professional-Tinting-Window-20-VLT-2-PLY-/171093747415?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item27d5fb66d7

 

The same seller on ebay has a lot of options.

 

Also 35% VLT.   This was more expensive since I couldn't find it in the right width at less than 100 feet rolls.  60"x100 foot, $140:

 

http://www.ebay.com/itm/High-Performance-Tint-Film-2-PLY-Roll-60-X100ft-Window-Tinting-35-VLT-/171100542162?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item27d66314d2

 

The choice of VLT level seemed to be based on projector brightness.  Darker is better for excellent blacks but you need a bright projector to overcome the inherent light loss.   Also the OP noted at there was a large amount of variability between manufacturers in this area.

 

4.   Diffuser layer.   The OP had pictures of two types of diffusers...one was a fabric looking thing, maybe a silk screen type of material from the t-shirt printing industry.  The second, which he settled on was a flexible PVC film material that was opaque unless pressed against a backing (which is what we would be doing).   The most like material for this was some sort of privacy window film like this:

 

$26 - 60" x 20 foot roll

http://www.ebay.com/itm/Home-Decorative-Privacy-Frosted-Film-60-x-10-feet-Bedroom-Bathroom-Glass-/181204411731?pt=US_Window_Film&hash=item2a309fe553

 

The benefit of this over fabric is cleaning ability and possibly a sharper picture due to no weave.   Fabric would be slightly cheaper though.

 

All layers were stretched tight and attached to the foam board with staples.

 

Using the cheapest options, all this comes to just over $100 + plus shipping and taxes.   So maybe $175 total.

 

My utmost thanks to New Designs the OP for taking the time to experiment and post his results.   Please correct anything that may be wrong.

 

Great work odpedxing!

 

A shame most of these sellers only ships to US and not world wide. Though, it gives a good idea of what to look for! Have you ordered any of these materials?

post #162 of 350
I haven't went all the way through the thread yet, but I did have a PM out to ND a couple of months ago. I think most of that info has been put in this thread. It would be nice to get the names of the materials he is using, but some are saying he is going the manufacturer route. All I can say is good luck. Being a screen manufacturer isn't easy and most would be surprised at how much you have to charge to make money.
post #163 of 350

I can help a little bit on his last pictured materials.  The last reflective material he posted, that was supposed to help with viewing cone is the material hydroponic grow tents are made out of.  It can be found on on popular auction sites by searching "grow tent fabric" or "grow tent material".  It is essentially a textured flexible mylar bonded to a fairly heavy and strong black canvas.  Has myone made any headway on the transparent diffuser film?

post #164 of 350

Hi there

 

I am new and tried some stuff out. Here are my bummers ;)

 

- Grow Orca Film does not work, it's completely diffuse and alone does look no different (or worse) than a standard diffuse screen

- Frosted Privacy Film does not work, because the material is still too reflective and causes bad hotspots

 

As Black layer, this would probably be good: http://www.gerriets.com/en/products/screens/SHOW-Laser-screen

As a Diffuse layer, maybe also a rear projection screen like this might be good: http://www.gerriets.com/en/products/screens/TRANSMISSION-LED-blending

 

The problem is, this shop only delivers from 100€ (VAT and shipping excluded) and only at least 5 running meters per product :(

post #165 of 350
Thanks for that information. I've been tied up with work but my new projector arrives tomorrow and I'll be able to start experimenting in earnest.

If the orca grow was just very diffuse, would it work with just a black layer and no privacy film on top or do you think the black layer would hot spot as well?

Sent from my Nexus 5 using Tapatalk
post #166 of 350

No it will not work. The Grow Orca is just a white film on some textile. It does not have any better characteristics regarding reflection, brightness or contrast than my cheap 1.1 gain roller screen :(

 

Also every window film I tried (tint or frozen) causes bad light artifacts ranging from heavy hotspots to glossy reflections. I think none of them work as a black layer nor diffusor :(

 

I actually would also doubt, that mylar does any good in a real live scenario. I tried with diffuse aluminium foil as a reflection layer, but this just gives weird random reflections and does not even brighten the image significantly when used with a black layer and diffusor. :/

 

So probably the reflective layer just needs to be a high gain projection film instead. Maybe something like this: http://www.gerriets.com/en/products/screens/REVUE-illuminated-ceilings.

 

Or a reflective base painting like https://www.facebook.com/Digital1crystalScreenPaint. This Make project also looks nice: http://makezine.com/projects/make-35/glass-bead-projection-screen/ I just ordered the issue for more details


Edited by cylab - 2/10/14 at 2:25pm
post #167 of 350
post #168 of 350

removed double post...


Edited by cylab - 2/12/14 at 6:27am
post #169 of 350
Got the projector and I'm starting with a bolt of drop cloth for testing. Actually I'm pretty amazed by the image quality in low light. It's badly washed out in high ambient light of course. On to phase 2...

Sent from my Nexus 5 using Tapatalk
post #170 of 350

Did some more material research. This looks like a top reflection-layer: https://www.amazon.co.uk/gp/product/B00EED01F8. I ordered a sample, so lets see, how it performs.

post #171 of 350

Hi guys! I recently watched a youtube film that TS made a while ago, and for a sec you see this little label on the diffuser film > 

 

Apparently he's using Optigrafix Diffusion FIlm LBMT .003/75um. I contacted Optigrafix but apparently they don't sell directly to end users, so they recommended me to try the consumer version Grafix .003" Matte Acetate.

 

Cylab, have you got your sample? 


Edited by Future Cinema - 2/18/14 at 12:41pm
post #172 of 350

Yeah, I got the 3M scotchlight today. It's obviously no good without a diffusor, because it's retro-reflective, but looks quite good with a diffusor. The Gerriets samples are unfortunately not as good as I hoped for, just because the materials are way too thick and opaque, so the Optigrafix is a good tip!

post #173 of 350
post #174 of 350

Here is my Test with the 3M Scotchlite: http://youtu.be/WdMQJaJ_fws

post #175 of 350
That's good work. I haven't bought any if the multilayer films yet because I haven't made up my mind but since the projector came I had to get something. I ended up with some black out cloth (white) as a baseline. Then because it's so easy to work with, I got a couple of yards of spandex....specifically matte milleskin charcoal and matte moleskin white as a backing. The charcoal is much darker than I've seen people try. They usually do silver.

The pics that follow are the spandex screen...about 78 inches wide and 90 something diagonal at 16:9 with some of the boc dropped over it.

OK...low light performance:

7y5epu6y.jpg

This is from avengers...a dark scene with scarlet flying with a copilot.

8ajuqepu.jpg

The boc obviously brings out note detail on the copilot but he's actually more illuminated in general so it's not just the screen.

So I'd give lowlight maybe a 7 out of ten.

Now look:

arejazan.jpg

This is full light. Notice the time bar at the bottom looks pretty normal.

Here's what the room looks like (sorry for the mess)…:

yby9u3yv.jpg

I think we can agree that's a pretty absurd amount of light....the overhead is doing about 3000 lumens, there's actually another 120w spot on the slopped ceiling at the back of the room over the stairs. Its literally pointing at the screen not straight down.

So not horrible. Not completely perfect but good for 60 bucks shipped.

Sent from my Nexus 5 using Tapatalk
post #176 of 350
Quote:
Originally Posted by cylab View Post
 

Wooohoo! Gerriets aggred to send me samples for:

 

  http://www.gerriets.com/en/products/screens/REVUE-illuminated-ceilings

 

  http://www.gerriets.com/en/products/screens/SHOW-Laser-screen 

 

  http://www.gerriets.com/en/products/screens/TRANSMISSION-LED-blending

 

 

 

So I may be able to post some results soon smile.gif

Quote:
Originally Posted by cylab View Post
 

Yeah, I got the 3M scotchlight today. It's obviously no good without a diffusor, because it's retro-reflective, but looks quite good with a diffusor. The Gerriets samples are unfortunately not as good as I hoped for, just because the materials are way too thick and opaque, so the Optigrafix is a good tip!

 

Do you have any pics on the black material from Gerriets? Did you try it together with a reflective layer?

 

Quote:

Originally Posted by cylab View Post
 

Here is my Test with the 3M Scotchlite: http://youtu.be/WdMQJaJ_fws

 

Great work Cylab! Regarding the window tint, you said 20% in the vid, but the spec on your youtube description said 30%, which is it? Regarding the self adhesive back on the diffuser film, I seems like a good thing. I would get piece of glass or plexiglass as a background plate since it's completely flat and mount everything there using a mic of water and dish soap.

 

Try this:

 • Mix 0,5 liters of water with only a few drops of dish soap.

 • Spray the soap water on a piece of glass / plexiglass.

 • Put the reflective layer on the glass

 • Remove the protective film on the window tint (and SAVE it!), spray soap water on top of the reflective layer and on the adhesive back of the window tint, they apply the tint on the reflective layer

 • Do the same thing with the diffusor film, remove the protective back and spray the adhesive back with a lot of water and also the top of the window tint, and then spray some more soap water on top of diffuser film. 

 • Now put the protective film on top of the diffuser (to prevent scratches etc.) and use some more soap water on top. You CAN'T use to much water, overdo!

 • Now squeeze out the water using a squeegee, just like you would apply the tint to a window.

 

Doing it like this would hopefully prevent bubbles from occurring. 

post #177 of 350
Quote:
Originally Posted by ogpedxing View Post

That's good work. I haven't bought any if the multilayer films yet because I haven't made up my mind but since the projector came I had to get something. I ended up with some black out cloth (white) as a baseline. Then because it's so easy to work with, I got a couple of yards of spandex....specifically matte milleskin charcoal and matte moleskin white as a backing. The charcoal is much darker than I've seen people try. They usually do silver.

The pics that follow are the spandex screen...about 78 inches wide and 90 something diagonal at 16:9 with some of the boc dropped over it.

 

Is this the one you used? http://spandexworld.com/c3/catalog/product/10491

Looks ok for a setup like that, what projector are you using? Normal or Eco Mode? Wonder how it would perform if you stretched it over mylar?

post #178 of 350
Quote:
Originally Posted by Future Cinema View Post
 

 

Great work Cylab! Regarding the window tint, you said 20% in the vid, but the spec on your youtube description said 30%, which is it?

 

Erm. I actually said and wrote 70% VLT ;-) Looks like I have to work an my accent...

VLT is Visual Light Transfer, which means it transmits 70% of the light, so it's 30% tinted.

 

Btw. the beamer used was http://www.amazon.com/BenQ-W1070-1080P-Theater-Projector/dp/B00A2T6X0K in SmartEco mode.

 

Thanks for the tip on applying the layers. I'll try next time, but I will probably use foam boards as a mount.

post #179 of 350
Quote:
Originally Posted by cylab View Post
 

 

Erm. I actually said and wrote 70% VLT ;-) Looks like I have to work an my accent...

VLT is Visual Light Transfer, which means it transmits 70% of the light, so it's 30% tinted.

 

Btw. the beamer used was http://www.amazon.com/BenQ-W1070-1080P-Theater-Projector/dp/B00A2T6X0K in SmartEco mode.

 

Thanks for the tip on applying the layers. I'll try next time, but I will probably use foam boards as a mount.

Haha jesus, I must have been really tired this morning, 70% indeed! ;-) no, you have good accent, I understand you very well! As I said, I must have been seriously tired when I got up this morning haha ;-)

 

Thanks for the info! Btw, what diffuser film did you use? I'll order a sample of the grafix matte acetate .003, but the shipping would probably take two weeks or more, but as soon as I get my hands on it I'll post a vid or pic.

post #180 of 350

The diffusor is a self adhesive window privacy film: http://www.velken.de/sichtschutzfolien/lichtdurchlaessige-folien/sichtschutzfolie-aetzglasdesign-weiss-matt. The german description translates to "edged glass design".

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: DIY Screen Section
AVS › AVS Forum › Display Devices › Screens › DIY Screen Section › DIY black screen tests