Choosing a Rear Projection Screen and Projector

mykatherine

Enthusiast
I am an engineering mind type and am having difficulty finding sources that explain in technical detail how rear projection screens work with different materials such as vinyl, pvc, and polyester in indoor applications with high day light, ambient light, and low to no light. What are the different coatings and textures and how do they work. What is the difference between a $29 4K 150 inch diagonal 16:9 screen, a $500 4K 150 inch diagonal 16:9 screen, and $1000 4K 150 inch diagonal 16:9 screen?

Also, I cannot find technical detail on the difference between a rear projector and a front projector, and the difference between a $50 projector, a $300 projector, and a $1500 projector.

Can someone please point me to a technical source that gives me technical details about rear projection screens and rear projectors?

Thanks and Regards
 
BMXTRIX

BMXTRIX

Audioholic Warlord
You should be reading through the hundreds of articles at Projector Central which gets into a fair bit of different things.

I'm not sure I've seen a good article on rear projection, but at the end of the day, I've yet to see a rear projection setup which is as sharp as a front projection setup. I think this is because the projector has two points of diffusion it must deal with as it passes from the rear of the film to the front of the film. So, you get a slightly softer image overall. Likewise, the diffusion layer is everything. It needs to retain sharpness while also providing an even spread of the light passing through it so that you don't get hot spotting or other image issues.

As for projectors, there are tons of articles about why $300 (and cheaper), no-name models are complete turds.

I had considered doing rear projection for many years before seeing several high dollar rear projection setups and deciding that I would never do rear projection in my life.

First, you need a large enough space behind the screen to put the projector... and that space needs to be as dark as possible to get the best image on the front side.

Second, you still have to content with a lot of normal front projection issues in the viewing area. While it can be brighter than normal front projection allows, a rear projection setup is still nowhere nearly as bright as a flat panel display. So, as ambient room light increases, the on-screen image loses quality. Yes, it can handle more ambient light, but it still does best as the room becomes darker and darker.

A $29 screen won't have any published half-gain angles, and you won't have any real world idea of how it performs. As price goes up, you will get measured data and typically much more of a real world idea of how performance will be.

All this said, if the goal is a 'decent looking' fun setup without a focus on perfection, you can get by with some very inexpensive materials and a cheaper projector for some dark room/outdoor viewing without a problem. Keep in mind, a $200 LED projector off Amazon is often 1/10th as bright as a $500 Optoma 1080p model. Plus, if you want a more serious setup, then considerations for audio (surround sound), light control, and a whole lot more need to be considered.
 

mykatherine

Enthusiast
Thanks @BMXTRX. This is an indoor, ambient to dark, on-location, portable setup with a graphics screen behind a person being interviewed and video recorded, so the better setup is rear projection. Front projection would be difficult to position the projector as the screen is about 3' - 5' feet behind the interview subject. I would also be concerned about screen reflection from a front projector. Like you have said, the cheaper screens give no technical graphs regarding gain, contrast, and viewing angle. However, Rose Brand, ShowTex, and Carl's Place do give "some" technical data on rear projection screens.

What I am going to do is to buy a single sheet of different qualities of the abovementioned manufacturer's rear projection screens and video projectors and run experiments under various room lighting conditions.

Thanks again.
 
BMXTRIX

BMXTRIX

Audioholic Warlord
Thanks @BMXTRX. This is an indoor, ambient to dark, on-location, portable setup with a graphics screen behind a person being interviewed and video recorded, so the better setup is rear projection. Front projection would be difficult to position the projector as the screen is about 3' - 5' feet behind the interview subject. I would also be concerned about screen reflection from a front projector. Like you have said, the cheaper screens give no technical graphs regarding gain, contrast, and viewing angle. However, Rose Brand, ShowTex, and Carl's Place do give "some" technical data on rear projection screens.

What I am going to do is to buy a single sheet of different qualities of the abovementioned manufacturer's rear projection screens and video projectors and run experiments under various room lighting conditions.

Thanks again.
If this is for presentation use, from an audience that just needs to see basics of charts and other such things, then almost any reasonable rear projection surface would be just fine. A big player is the projector which will be used and the screen size. Short throw projectors are traditionally not very bright and most commercial environments have VERY poor light control. This means that there is typical florescent lighting within a room and at least 80 advertised lumens are the absolute minimum projector requirement per square foot of screen space. A projector with either 1920x1080 or 1920x1200 resolution is all that is needed. 4K resolution with a connection to any computer running at 100% resolution produces text and details which the audience wouldn't be able to read, so it's a waste of money to spend more on resolution.

It is almost never a waste of money to spend more on brightness.

The slight desharpening of rear projection will be irrelevant in such a use case as what you have.

Throw distance will matter a great deal. The projector will matter a great deal. It's fine to say it is more convenient to use rear projection, but you need the space behind the screen to place the projector, which could be very problematic. The solution is not throwing the term 'ultra short throw' (UST) at it, because UST requires a VERY flat surface and with rear projection, it needs extremely high diffusion for an even image. Those are two big factors that work against it. As well, UST is much more difficult to setup properly than standard throw. Even the brighter and more typical short throw models need a really flat screen surface for proper results.

I would come up with some goals. Some very loose desires, and then see what budget you will need to deliver those results. Start with a desired screen size and work out the square footage, multiply by 80 and that will be your minimum lumen requirement, then throw out a throw distance to achieve that screen size and see if there are any models which will do what you want and are bright enough.

For example. Let's say you want a 140" diagonal 16:9 screen.
122" wide x 69" tall = 8,418 square inches or about 58.5 square feet. So, 4,680 lumens minimum requirement. Or, about a 5,000 lumen projector for acceptable results.

I would ideally use a model like this: https://www.projectorcentral.com/Panasonic-PT-VMZ50U.htm
It can throw that 140" diagonal from as close as 11'1" or as far as 18' from lens to screen and is reasonably priced. No lamps to replace which increases reliability and should provide a more consistently bright image during use.

What if you want shorter throw? Well, you still need that brightness, so your list looks something like this:

Things get expensive, and almost every projector needs a specialty add-on lens which will cost several thousand dollars.

While a model like this may jump out as an option... https://www.projectorcentral.com/Optoma-ZU500USTe.htm
Understand that by the specs, it is only rated to support a screen size of up to 120" diagonal. This won't actually work on a 140" screen with proper focus.

You would need to go to something like this for an all in one UST solution which can handle that 140" screen size...

So, yeah, this is why your original question is very complicated, because you need to nail all the fine points of what you want before you can really get into "What kind of screen should I get?" type of questions. I would then actually buy the projector, and probably get some screen samples to try to figure out which I liked the most with the specific projector which was purchased.
 

mykatherine

Enthusiast
If this is for presentation use, from an audience that just needs to see basics of charts and other such things, then almost any reasonable rear projection surface would be just fine. A big player is the projector which will be used and the screen size. Short throw projectors are traditionally not very bright and most commercial environments have VERY poor light control. This means that there is typical florescent lighting within a room and at least 80 advertised lumens are the absolute minimum projector requirement per square foot of screen space. A projector with either 1920x1080 or 1920x1200 resolution is all that is needed. 4K resolution with a connection to any computer running at 100% resolution produces text and details which the audience wouldn't be able to read, so it's a waste of money to spend more on resolution.

It is almost never a waste of money to spend more on brightness.

The slight desharpening of rear projection will be irrelevant in such a use case as what you have.

Throw distance will matter a great deal. The projector will matter a great deal. It's fine to say it is more convenient to use rear projection, but you need the space behind the screen to place the projector, which could be very problematic. The solution is not throwing the term 'ultra short throw' (UST) at it, because UST requires a VERY flat surface and with rear projection, it needs extremely high diffusion for an even image. Those are two big factors that work against it. As well, UST is much more difficult to setup properly than standard throw. Even the brighter and more typical short throw models need a really flat screen surface for proper results.

I would come up with some goals. Some very loose desires, and then see what budget you will need to deliver those results. Start with a desired screen size and work out the square footage, multiply by 80 and that will be your minimum lumen requirement, then throw out a throw distance to achieve that screen size and see if there are any models which will do what you want and are bright enough.

For example. Let's say you want a 140" diagonal 16:9 screen.
122" wide x 69" tall = 8,418 square inches or about 58.5 square feet. So, 4,680 lumens minimum requirement. Or, about a 5,000 lumen projector for acceptable results.

I would ideally use a model like this: https://www.projectorcentral.com/Panasonic-PT-VMZ50U.htm
It can throw that 140" diagonal from as close as 11'1" or as far as 18' from lens to screen and is reasonably priced. No lamps to replace which increases reliability and should provide a more consistently bright image during use.

What if you want shorter throw? Well, you still need that brightness, so your list looks something like this:

Things get expensive, and almost every projector needs a specialty add-on lens which will cost several thousand dollars.

While a model like this may jump out as an option... https://www.projectorcentral.com/Optoma-ZU500USTe.htm
Understand that by the specs, it is only rated to support a screen size of up to 120" diagonal. This won't actually work on a 140" screen with proper focus.

You would need to go to something like this for an all in one UST solution which can handle that 140" screen size...

So, yeah, this is why your original question is very complicated, because you need to nail all the fine points of what you want before you can really get into "What kind of screen should I get?" type of questions. I would then actually buy the projector, and probably get some screen samples to try to figure out which I liked the most with the specific projector which was purchased.
Thanks very much BMXTRX! This is the type of feedback I needed. I need to take this and digest it. I will reply back to this conversation in the near future with my findings.
 
BMXTRIX

BMXTRIX

Audioholic Warlord
Thanks very much BMXTRX! This is the type of feedback I needed. I need to take this and digest it. I will reply back to this conversation in the near future with my findings.
Feel free to ask any follow up questions you may have along the way. I've been at this for a few years. Also, don't worry about the misspelling, it happens. No big deal.
If you add an @ symbol before a name on many forums, it will autofill the members who have the first few characters and tag them. ie: @mykatherine :D
 
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