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Discussion Starter #1
I just received my projector today, an Epson 3800. I set it up in the living room at the max. throw distance of 14' to ensure it functions. This projector will be installed in a house I'm currently building, where I will have plenty of room to place the projector 24' worth of potential.

Now, I've used projectorcentral to calculate the throw distance for my screen size of 135" which is 16'.

My question is: is it better to utilize the zoom and place the projector as close as possible to the screen, in this case about 12', for the maximum amount of light? Does placing the projector that close and using the zoom to get to 135" effect the picture quality? Is it better to keep the zoom at 50% and adjust the physical distance of the projector to the screen? I ask this so I can get my outlet/HDMI drop at least as close to the correct measurement as possible.

Heres a snap shot of my test on the wall before it got boxed back up. Thats about 140" screen size.

3119835
 

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General consensus is the closer the projector is to the screen the less light loss through the lens so it's brighter. Placed as far away as you can it uses more of the sweet spot of the lens for a sharper picture but more light loss so dimmer. In a nut shell if you don't need every drop of lumens put the projector right in the middle of its range. Since you have the projector in hand test the different scenarios accounting for the position and lens shift you will need as every individual unit has variances in it QC of the lens. The 3800 has been known to have focus uniformity issues with using close to max shift so placing the projector farther out with loss of some lumens may help.
 

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Discussion Starter #3
I will be able to drop the projector down to nearly in line with the center of the screen so that should help
 

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I will be able to drop the projector down to nearly in line with the center of the screen so that should help
I guess I don't understand. If you ceiling mount and drop it in line with the center of the screen peoples heads will get in the way of the image.
 

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I just received my projector today, an Epson 3800. I set it up in the living room at the max. throw distance of 14' to ensure it functions. This projector will be installed in a house I'm currently building, where I will have plenty of room to place the projector 24' worth of potential.

Now, I've used projectorcentral to calculate the throw distance for my screen size of 135" which is 16'.

My question is: is it better to utilize the zoom and place the projector as close as possible to the screen, in this case about 12', for the maximum amount of light? Does placing the projector that close and using the zoom to get to 135" effect the picture quality? Is it better to keep the zoom at 50% and adjust the physical distance of the projector to the screen? I ask this so I can get my outlet/HDMI drop at least as close to the correct measurement as possible.

Heres a snap shot of my test on the wall before it got boxed back up. Thats about 140" screen size.

View attachment 3119835
The short answer is place the projector in the room where it makes the most sense.

You've indicated that you have a 24' long room. If it were me, I'd mount it near the end of the room and behind the seating area so as to minimize projector fan noise and keep the unit out of the field of view. Also, mount it a few inches above the top of the screen and high enough so as to not be a problem for anyone bumping their head.

Placing the projector near the center of the screen, behind the seating area, has the potential of interference from the seated people casting shadows.

Placing the projector in front of the seating area will always have the projector in the field of view, if only in ones peripheral vision and a distraction.

In general, placing a projector at its shortest shortest throw distance yields higher brightness. However, placing the projector at it's longest throw distance, using the same lens, will often improve contrast.

Light from a point source behaves according to the inverse square law. In short, if you double the distance between the light source and a given distance, the light illuminates a surface area four times greater than the one before and the light quantity will be 25% of that of the original distance.

But, the zoom lens allow you to concentrate the light over a smaller area as the distance increases so the net light loss is not as great.

To simplify, for your given screen size of 135" and the working zoom range of the HC3800 lens, any change in light level intensity would be de minimis or only 2-3 foot lamberts. It's not going to be enough that will make a difference or that you will even notice.

Additionally, the HC3800 has more than enough lumens to light a 135" screen at its maximum throw. Throw distance range for the HC3800 with a 135" screen is 12'-11" to 21'-1".

Anecdotally, it's been reported that there are some problems with focus uniformity when using extreme lens shift settings with the HC3800. My suggestion of mounting some inches above the top of the screen is not going to use much lens shift. As a mater of fact, using a 135" screen with the HC3800 ceiling mounted, the projector has over 6" of offset. In other words, the projector can be placed some where 6-7" above the top of the screen and never use any lens shift.

Sounds like you're going to have a very nice room in the new house. Again if it were me, I'd mount it around 20' and enjoy the room.
 

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Discussion Starter #6
The short answer is place the projector in the room where it makes the most sense.

You've indicated that you have a 24' long room. If it were me, I'd mount it near the end of the room and behind the seating area so as to minimize projector fan noise and keep the unit out of the field of view. Also, mount it a few inches above the top of the screen and high enough so as to not be a problem for anyone bumping their head.

Placing the projector near the center of the screen, behind the seating area, has the potential of interference from the seated people casting shadows.

Placing the projector in front of the seating area will always have the projector in the field of view, if only in ones peripheral vision and a distraction.

In general, placing a projector at its shortest shortest throw distance yields higher brightness. However, placing the projector at it's longest throw distance, using the same lens, will often improve contrast.

Light from a point source behaves according to the inverse square law. In short, if you double the distance between the light source and a given distance, the light illuminates a surface area four times greater than the one before and the light quantity will be 25% of that of the original distance.

But, the zoom lens allow you to concentrate the light over a smaller area as the distance increases so the net light loss is not as great.

To simplify, for your given screen size of 135" and the working zoom range of the HC3800 lens, any change in light level intensity would be de minimis or only 2-3 foot lamberts. It's not going to be enough that will make a difference or that you will even notice.

Additionally, the HC3800 has more than enough lumens to light a 135" screen at its maximum throw. Throw distance range for the HC3800 with a 135" screen is 12'-11" to 21'-1".

Anecdotally, it's been reported that there are some problems with focus uniformity when using extreme lens shift settings with the HC3800. My suggestion of mounting some inches above the top of the screen is not going to use much lens shift. As a mater of fact, using a 135" screen with the HC3800 ceiling mounted, the projector has over 6" of offset. In other words, the projector can be placed some where 6-7" above the top of the screen and never use any lens shift.

Sounds like you're going to have a very nice room in the new house. Again if it were me, I'd mount it around 20' and enjoy the room.
Thank you for that info, very helpful! I will plan to mount it at about 17' then, that is far enough back from the seating as to not be noticed.
 

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As a mater of fact, using a 135" screen with the HC3800 ceiling mounted, the projector has over 6" of offset. In other words, the projector can be placed some where 6-7" above the top of the screen and never use any lens shift.
This is 100% untrue. The projectors default location with zero lens shift is dead center of the screen. It take 50% of the available 60% shift to get to the top of the screen so 6" above the screen lens shift will be at or close to its max.
 
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This is 100% untrue. The projectors default location with zero lens shift is dead center of the screen. It take 50% of the available 60% shift to get to the top of the screen so 6" above the screen lens shift will be at or close to its max.
I guess mine must work different then...
 

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My 3800 is mounted on the ceiling and the lens is about 6 inches underneath the top edge of the 100" screen so it is pretty high up, 2 feet below the ceiling and you can't hear the fan in medium or low. My MLP sits directly below it...not once have I looked up thinking about fan noise. It is not an issue like some other projectors I have had as this fan is quiet.

For the record, 6" below the top of the screen is about where the image is square on the screen without any adjustment for me. If was to move the projector down to the middle of the screen as someone else suggested WRONGLY, the image would be on the floor. The image has an offset which projects up from the lens so it can sit down on a table or up near the ceiling projecting to a screen that is on the center of the wall.

I'm not sure what that person is talking about...frankly it is kind of a weird thing to say so definitively like that.

Moving along... as far as how far away from the screen it is, I too thought about this question for a bit. The fact is the 3800 is so bright that you don't have to worry about being as close as possible like that... Just using the suggested distance in the chart is what I ended up doing and the image is awesome. I have zero focus inconsistency... it is nice and clear all across the screen. Makes me wonder if the people that have focus issues went all the way to the front or back of the range.
 

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This is 100% untrue. The projectors default location with zero lens shift is dead center of the screen. It take 50% of the available 60% shift to get to the top of the screen so 6" above the screen lens shift will be at or close to its max.
Default location is dead center of the screen? Wtf?

No...just no. It would be nice if you weren't so definitive with your incorrect assertions. People who don't actually know this stuff already are reading what you write and likely getting confused.

You know we can just do that with our projectors and see what happens right? Of course we wouldn't do that because we all know already that it would either put the image on the ceiling or on the floor depending on your setup because of the built-in offset to the projected image.

Does your 3550 have an offset? Do you project straight onto the screen from dead center?
 

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The Epson 3800 has 0% fixed off set (default is exactly in the center of the screen).
 

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Discussion Starter #12
The Epson 3800 has 0% fixed off set (default is exactly in the center of the screen).
I plan to make my own mount, a suspended shelf with all thread, so my projector will not be up-side-down as with most ceiling mounts. With that 0% fixed offset, it should not matter which way the projector is oriented, right? In either case one would need to use some amount of lens shift if the projector was not exactly center with the screen, correct?
 

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Default location is dead center of the screen? Wtf?

No...just no. It would be nice if you weren't so definitive with your incorrect assertions. People who don't actually know this stuff already are reading what you write and likely getting confused.

You know we can just do that with our projectors and see what happens right? Of course we wouldn't do that because we all know already that it would either put the image on the ceiling or on the floor depending on your setup because of the built-in offset to the projected image.

Does your 3550 have an offset? Do you project straight onto the screen from dead center?
Yes my BenQ 3550 has a fixed off set and the default location is just above the top of the screen inverted with a small amount of shift. As long as we are talking about the Epson 3800 I am not wrong, you must be confused and thinking about a different projector.
 

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I plan to make my own mount, a suspended shelf with all thread, so my projector will not be up-side-down as with most ceiling mounts. With that 0% fixed offset, it should not matter which way the projector is oriented, right? In either case one would need to use some amount of lens shift if the projector was not exactly center with the screen, correct?
Yeah the odds of you mounting it precisely centered both horizontally & vertically are near zero. You'll need a bit of shift but you could orient it either way.
 

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Default location is dead center of the screen? Wtf?

No...just no. It would be nice if you weren't so definitive with your incorrect assertions. People who don't actually know this stuff already are reading what you write and likely getting confused.

You know we can just do that with our projectors and see what happens right? Of course we wouldn't do that because we all know already that it would either put the image on the ceiling or on the floor depending on your setup because of the built-in offset to the projected image.

Does your 3550 have an offset? Do you project straight onto the screen from dead center?
@Snausy - Lens shift and neutral positions are very poorly documented by different manfucturers.

Projectors with significant offset almost always have a lens neutral position at 0%, and call that 0% the center of the image. So, 50% down from the top, and 50% up from the bottom. This is what JVC uses and Sony uses on most of their models. It is also what Epson uses on their 3200, 3800, 4000, and 5000 series models.

For a projector like the 3200, which has +/-60% lens shift, it actually delivers what BenQ would call 120% lens shift. But, it's more accurate to call it a +/- number from a neutral position.

Projectors with 'minimal' lens shift (about 10% to 20%) often use a lens shift range that starts from the top edge or bottom edge of the image. IMO this is wrong and conflicts with how measurements are already taken. While the BenQ 3550 claims 10% lens shift, in comparison to the Epson, using standard format, it has +/- 5% offset with a neutral position that is 55% below the centerline of the image. If all manufacturers would follow one standard way of describing lens shift... and for that matter offset, then we could actually have a discussion which people can follow.

The problem is that you have manufacturers like AAXA who claim that their projector has 100% offset. WTF does that mean? Oh, it means the center of their lens is at the bottom edge of the image. No, that's not 100% offset. That is -50% offset. The center of the lens is 50% of the image height below the center of the screen. If we are measuring from the bottom of the screen, lets ALWAYS do that instead of doing it half the time. If we are measuring from the top of the screen, let's do it all the time.

I don't think your wrong, but you also aren't right. It's important that we all know that measuring offset and lens shift is completely screwy and it depends, very much, on the exact projector model we are discussing.

Go figure.
 

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My 3800 is sitting on a ceiling mount above my head right now(not theoretical)and the lens is 5" below the top of my 100" screen. PJ is square with no big lens adjustments...

Are we saying different things here?
 

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@Snausy - Lens shift and neutral positions are very poorly documented by different manfucturers.

Projectors with significant offset almost always have a lens neutral position at 0%, and call that 0% the center of the image. So, 50% down from the top, and 50% up from the bottom. This is what JVC uses and Sony uses on most of their models. It is also what Epson uses on their 3200, 3800, 4000, and 5000 series models.

For a projector like the 3200, which has +/-60% lens shift, it actually delivers what BenQ would call 120% lens shift. But, it's more accurate to call it a +/- number from a neutral position.

Projectors with 'minimal' lens shift (about 10% to 20%) often use a lens shift range that starts from the top edge or bottom edge of the image. IMO this is wrong and conflicts with how measurements are already taken. While the BenQ 3550 claims 10% lens shift, in comparison to the Epson, using standard format, it has +/- 5% offset with a neutral position that is 55% below the centerline of the image. If all manufacturers would follow one standard way of describing lens shift... and for that matter offset, then we could actually have a discussion which people can follow.

The problem is that you have manufacturers like AAXA who claim that their projector has 100% offset. WTF does that mean? Oh, it means the center of their lens is at the bottom edge of the image. No, that's not 100% offset. That is -50% offset. The center of the lens is 50% of the image height below the center of the screen. If we are measuring from the bottom of the screen, lets ALWAYS do that instead of doing it half the time. If we are measuring from the top of the screen, let's do it all the time.

I don't think your wrong, but you also aren't right. It's important that we all know that measuring offset and lens shift is completely screwy and it depends, very much, on the exact projector model we are discussing.

Go figure.
Thanks for that...I am 93% sure that I understood 87% of what you wrote.
 

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My 3800 is sitting on a ceiling mount above my head right now(not theoretical)and the lens is 5" below the top of my 100" screen. PJ is square with no big lens adjustments...

Are we saying different things here?
You are almost entirely maxed out on your lens shift. If you adjust your lens shift the other direction, you can put almost the entire image on your ceiling. I think you may not have played with your lens shift a ton.

I've checked your manual to confirm this... Page 25-28 shows how much lens shift you didn't even know you have.

But, yes, you should go ahead and if you are game, go ahead and roll that lens shift knob and watch what happens to your image. See how much lower you can go... then go as far as you can the other direction.

Always worth learning something new every day.
 

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I am game...

And the result is my image can still go down another 2 ft past the bottom of the screen... But it can go up quite a bit more as you said. Obviously I just threw the 3800 up on the mount where the old projector was and it worked fine.

It seems as though the left to right adjustment has a middle "click" point that sticks there indicating you are midway... but there is no middle "click" point going up and down.

As I said I still have two feet of play and my focus is uniform and good so whatever...

Quite right about learning though...now I know.

"Live as though you'll die tomorrow, learn as though you'll live forever." - Gandhi
 

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I am game...

And the result is my image can still go down another 2 ft past the bottom of the screen... But it can go up quite a bit more as you said. Obviously I just threw the 3800 up on the mount where the old projector was and it worked fine.

It seems as though the left to right adjustment has a middle "click" point that sticks there indicating you are midway... but there is no middle "click" point going up and down.

As I said I still have two feet of play and my focus is uniform and good so whatever...

Quite right about learning though...now I know.

"Live as though you'll die tomorrow, learn as though you'll live forever." - Gandhi
Assuming your talking about a 100" diag screen that is 49 inches high and the lens center of your projector is truly 5" below the top of your screen and perfectly level with no keystone enabled according to Epson's spec your image should only be able to be lowered 9.9" below the top of the screen. So either your measurements are off or your projector is not within Epson's advertised spec, I could see some error in tolerance but 2' is way off. If you do have keystone enabled and your projector is tilted down you should correct it as this is degrading your image as you have more then enough shift to correct it.
 
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