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Author Topic: Rear projection vs. front projection  (Read 15700 times)

john sanders

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Rear projection vs. front projection
« on: March 23, 2012, 10:02:12 am »

I own a 6ooo lumen projector that will be needed for an outdoor/early evening screening. Would a rear projection type projector provide me with a sharper, brighter image? I'm thinking yes, due to the fact that the projector would be so much closer to the screen.
I would appreciate your input and advice.
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Charlie Zureki

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Re: Rear projection vs. front projection
« Reply #1 on: March 23, 2012, 11:55:25 am »

I own a 6ooo lumen projector that will be needed for an outdoor/early evening screening. Would a rear projection type projector provide me with a sharper, brighter image? I'm thinking yes, due to the fact that the projector would be so much closer to the screen.
I would appreciate your input and advice.


   Ambient light is ambient light...doesn't matter where it comes from.  If you can control any detrimental light...you're good.

   Hammer
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Brad Weber

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Re: Rear projection vs. front projection
« Reply #2 on: March 23, 2012, 12:20:21 pm »

I own a 6ooo lumen projector that will be needed for an outdoor/early evening screening. Would a rear projection type projector provide me with a sharper, brighter image? I'm thinking yes, due to the fact that the projector would be so much closer to the screen.
I would appreciate your input and advice.
A projector is a projector, there is usually no real differentiation between a 'front projection' projector and a 'rear projection' projector, it is typically simply a selection made in the projector setup menu along with whether the projector is desktop or ceiling mounted.

Also, 6,000 lumens over the same size image equates to the same image brightness regardless of how far away the projector is.  Different lenses may allow the projector to create the same image size at different distances and different lenses may have lesser or greater losses depending on the optics and quality but the throw distance, or distance from projector to screen, does not by itself affect the image brightness.

Where rear projection, perhaps combined with a short throw lens, may have an advantage is in making it easier to keep ambient light off the screen.  In an outdoor application it is often easier to create a projection 'room' behind a screen than to try to control the light coming from the audience side.
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Charlie Zureki

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Re: Rear projection vs. front projection
« Reply #3 on: March 23, 2012, 12:34:36 pm »

A projector is a projector, there is usually no real differentiation between a 'front projection' projector and a 'rear projection' projector, it is typically simply a selection made in the projector setup menu along with whether the projector is desktop or ceiling mounted.

Also, 6,000 lumens over the same size image equates to the same image brightness regardless of how far away the projector is.  Different lenses may allow the projector to create the same image size at different distances and different lenses may have lesser or greater losses depending on the optics and quality but the throw distance, or distance from projector to screen, does not by itself affect the image brightness.

Where rear projection, perhaps combined with a short throw lens, may have an advantage is in making it easier to keep ambient light off the screen.  In an outdoor application it is often easier to create a projection 'room' behind a screen than to try to control the light coming from the audience side.

  +1
  Hammer
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Aram Piligian

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Re: Rear projection vs. front projection
« Reply #4 on: March 23, 2012, 02:25:30 pm »

As a former coworker of mine at a rental shop pointed out to a customer over the phone:  "We don't have any projectors that are brighter than the sun."   8)
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john sanders

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Re: Rear projection vs. front projection
« Reply #5 on: March 24, 2012, 10:25:02 am »

For some reason I assumed that a rear projection unit would also be a short throw thus brighter. Typically, with a rear projection unit would you also need a specialized screen?
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Gary Creely

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Re: Rear projection vs. front projection
« Reply #6 on: March 24, 2012, 01:17:01 pm »


   Ambient light is ambient light...doesn't matter where it comes from.  If you can control any detrimental light...you're good.

   Hammer

You lose Lumens with rear projection.

Front projection will offer you the best pop with the right screen. Also it depends on the screen material. Typically the higher the gain the more narrow the viewing cone is, so you need to keep that in mind. My experience is you lose about 30% of your lumens with rear projection. (or front projecting on a rear projection screen material)

If you stand with the projector in a rear projection set up you can see the image pretty well, so that light you are seeing is light bouncing back the wrong direction.

The other thing you can do is make the image size as small as practically possible to have a higher concentration of light, hence better contrast.


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Brad Weber

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Re: Rear projection vs. front projection
« Reply #7 on: March 24, 2012, 02:41:20 pm »

For some reason I assumed that a rear projection unit would also be a short throw thus brighter. Typically, with a rear projection unit would you also need a specialized screen?
There are front projection screen materials, rear projection screen materials and 'dual purpose' projection screen materials.

There are few dedicated 'rear projection' projectors, they are many projectors that can be ordered with, or for which are available, short throw lenses.

If you had a fixed lens then moving the projector closer to or further from the screen affects the image brighter because the image size would change, getting smaller as the projector moves closer and larger as the projector moves further away.  However, by using different lenses and/or zoom lenses you can maintain the same image size, and thus basically the same image brightness, at different distances.
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drew gandy

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Re: Rear projection vs. front projection
« Reply #8 on: March 24, 2012, 08:59:50 pm »

Some of what I've learned on the subject to add to the mix... 

Generally speaking it's the contrast, not the total brightness that matters for image quality (including readability).  Many rear projection surfaces are somewhat better than a matte front screen at dealing with ambient light on the viewing side of the screen yielding a better contrast ratio. Of course, the brightness of the image has to be similar to the brightness of the environment or the contrast doesn't matter much. This is because the iris (in the human) opens or closes according to the overall brightness coming into the eye.  In outdoor daylight conditions our irises tend to close down quite a bit (compared to a movie theater for instance) making the image appear too dark and lower in detail.  A projection room behind a rear screen is likely a good idea for this purpose, especially if you can also "frame" the screen with a significant dark border as this makes the image appear brighter. 
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TJ (Tom) Cornish

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Re: Rear projection vs. front projection
« Reply #9 on: March 26, 2012, 10:02:05 am »

I own a 6ooo lumen projector that will be needed for an outdoor/early evening screening. Would a rear projection type projector provide me with a sharper, brighter image? I'm thinking yes, due to the fact that the projector would be so much closer to the screen.
I would appreciate your input and advice.
Rear projection also has the advantage of keeping the projector out of sight lines and foot traffic, and would be my choice unless you don't have any throw room behind the screen.

Most daytime outdoor "projection" is done with LED wall-type screens, as they are brighter than most projectors and have a chance of working in non-optimal lighting circumstances, though sometimes at a cost of picture quality.
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