I am finishing my home theater room and bought the HD70 based on the reviews here. My ceiling is only 86" and I am running into an issue with the offset for a 106" screen. I read many posts here that talked about the offset. Some say it is 33% and some say it is 28%. Even worse, the calculator on optoma website gave me an offset of 18.7" for a 106 diagonal (52" tall) resulting in an offset of 36% !!!!
What is the real number? Your hellp is greatly appreciated.
Also does the offset vary based on where I mount the projector on the ceiling ? (12 feet vs 14 feet)
Thanks a lot guys.

Offset is based on the image size. For the HD70, multiple the image height by 28%. It does not matter what the distance is, just the image size.

vsreeniv, hate to be the bearer of bad news if your heart is set to ceiling mount. I'm sure if I'm completely wrong someone will give you the correct answer, but at 7ft 2inches I don't see how you will possibly be able to ceiling mount this unit and have a good picture.

It's a great PJ and if you consider table mounting I think you'll be very happy.

86" ceiling
- 4" ceiling mount
-15" offset
- 52" image
= 15" above the floor, low but not too low if only one row of seats.


OR, put on bottom shelf of end table and project up the wall.

86" ceiling
- 4" ceiling mount
-15" offset
- 52" image
= 15" above the floor, low but not too low if only one row of seats.


OR, put on bottom shelf of end table and project up the wall.


Ok Mr. Smarty Pants. :D

Tech, what do you really think for what he's asking. Wouldn't the bottom shelf as you have posted be the better answer?

Ok Mr. Smarty Pants. :D

Tech, what do you really think for what he's asking. Wouldn't the bottom shelf as you have posted be the better answer?

Yes it would but most people have pets / kids / hands-on neighbors that might make the shelf less desirable so I like to make sure they know what the ceiling will give them.

So there is no question the offset is 28%?

Yes it would but most people have pets / kids /


I thought that is what a leash is for, namely pets and kids. :p

thanks a lot for your response guys...
is 15" above the floor too low???? I also have a "stage" for the first row of seats... it is 2" thick... and 6feet long
I am building a dedicated home theater room.. still dont understand why I have only 86" available... they are putting the drywall only now.. Is there anything I can do to negate this offset issue? I did read about tilt and keystoning.. not sure whether i would want to do it though....

vsreeniv, an additional question would be are you going to use a perforated screen. If not I would be concerned your center channel being too low.

I am going to be using the DIY laminate screen (found it in this forum).. Yeah I agree that my center will be low..
so according to the posts here
86" ceiling
-3.25" (mount direct PMS flush mount)
-15" (offset for 52" height)
-----
67.75
-----
-52" (image)
-2" (border trim at the bottom. The top border trim will be accounted for within the offset)
-----
13.75" from the floor
-----
maybe it is indeed low :(
i got an awesome deal on my projector... 700 shipped...and dont have the heart to exchange it for one with the lens shift. Also end table is not an option since we are going to use this place only as a home theater room with 2 rows of seats. So I have to look at ways to ceiling mount it....
Your suggestions are most welcome...

So there is no question the offset is 28%?

Just looking at the manual, it looks like it may be 30% but with all that math/trig on the page, it's hard to say:

H' = L x tan(A)

H' = offset
L = throw
A = 8.13 degrees from center of lens to bottom of image
B = 26.5 degrees from center of lens to top of image

Good luck!

I am going to be using the DIY laminate screen (found it in this forum).. Yeah I agree that my center will be low..
so according to the posts here
86" ceiling
-3.25" (mount direct PMS flush mount)
-15" (offset for 52" height)
-----
67.75
-----
-52" (image)
-2" (border trim at the bottom. The top border trim will be accounted for within the offset)
-----
13.75" from the floor
-----
maybe it is indeed low :(
i got an awesome deal on my projector... 700 shipped...and dont have the heart to exchange it for one with the lens shift. Also end table is not an option since we are going to use this place only as a home theater room with 2 rows of seats. So I have to look at ways to ceiling mount it....
Your suggestions are most welcome...

Lean your the top of your screen closer to you and tilt the PJ lens up a little to move the image up the wall. I would tilt the PJ until you have it where you want it and mark the bottom of the image. Then, set up the screen so the bottom is hooked to the wall at that height and then lean the top out from the wall until the image looks right. Might be an inch, you will have to fiddle with it.

I had the same problem and finally decided to table mount anyway. Wound up splitting my front row (4 seats originally) into two sets. Bought a cheap (we're talking $15) tv stand that would be designed for say a 20in tv. My theater seats are in black microfiber so the wife actually took black microfiber and tricked out the stand so to speak and made it match the seats.

Anyway, I use the lowest shelf and project on a DIY painted screen at 118" diagonal. The popcorn and soda machine/snack area are dedicated to the left hand side so anyone setting on the left can get up at anytime and will not effect the show. Of course anyone setting to the right and doing the same walks right in front of the projector which is a drawback.

The positive is simply, it is so much easier to set things up and make adustments for your screen especially if your new at this (like myself). I had thought about ceilling mounting, but after looking at tilting the projector and keytoning, etc; I decided the #1 priority for me was the picture. I didn't want to have to use tricks and mirrors so to speak to get the picture in shape.

The other guys on here are far more knowledgable than I. As stated I'm pretty much a newbie, but have found when dealing with the low ceiling and trying to get the center channel at a decent ear level it was easier to low table mount.

vsreeniv, an additional question would be are you going to use a perforated screen. If not I would be concerned your center channel being too low.

RWB... I plan to mount my center channel upside down (polk has this feature that will hopefully be better)

I don't know about percentages but with my table mounted HD70, the bottom of the image (or the top if ceiling mounted) is about 21" higher than the lens. I have about an 8 ft. ceiling (96") and with my Panoview screen (45" tall), even with the PJ mounted flush to the ceiling, the Optoma has way too big of an offset for it to work in my room.

If I were you, I'd stick with a table mount and concentrate on installing the screen correctly.

I don't know about percentages but with my table mounted HD70, the bottom of the image (or the top if ceiling mounted) is about 21" higher than the lens. I have about an 8 ft. ceiling (96") and with my Panoview screen (45" tall), even with the PJ mounted flush to the ceiling, the Optoma has way too big of an offset for it to work in my room.

If I were you, I'd stick with a table mount and concentrate on installing the screen correctly.Your HD70 must not be level. I have a 92" screen which is 45" tall and my offset is 14 inches.

Your HD70 must not be level. I have a 92" screen which is 45" tall and my offset is 14 inches.

I agree.. the offset should not be more than 16" (worst case). So you should comfortably be able to ceiling mount the projector

folks..
I just learnt from my contractor that I can gain another 3" .. so total height is 89". So is 17" of the floor good enough for a second row of seats?? the length of the room is 16 feet
Also I have a stage which is 2" high for the first row. Will this help even if the screen is a little low?

Everyone stop flippin out please!!
My setup is this with a HD70 and a 92" DIY screen.
Ceiling height is 84"....get that 84"!
Screen height off the floor is a tall 33"!
Projector is mounted 12' back, when i used a 106" it was 13' back.
I have a $11 Ebay ceiling mount, 4" off the ceiling.
Keystone is set at only -2 vertical, 0 horizontal, most likely due to my homemade border not being perfectly square.
I do have my PJ tilted up slightly...not a big deal, if you think it is...get over it and sit down!
My screen is hanging off the ceiling with a woodtove under it, hence the 33" height, the stove is not used anymore unless a 3 day power outage which would never happen, it is used to place my center channel on.


I never measured anything, i didn't care about offset number's i just mounted it and enjoyed it!!

Getting all worked up thinking it wont work...just do it!!

Your looking at a poor man's old cellar, which wasn't used for 25 yr's.

http://img.photobucket.com/albums/v406/Bud-man/DSCN0339.jpg
Hate wires?....i dont!, just dont lookup!, i had no choice, solid ceiling and paneling, not going to rip it all out to run some wires.....get over it and sitdown!!
http://img.photobucket.com/albums/v406/Bud-man/DSCN0341.jpg
http://img.photobucket.com/albums/v406/Bud-man/DSCN0342.jpg

Everyone stop flippin out please!!

I never measured anything, i didn't care about offset number's i just mounted it and enjoyed it!!

Getting all worked up thinking it wont work...just do it!!


Three points here.

#1 Where did you get the idea anyone was flippin out? The original thread asked for peoples advice/opinions and and that's all we have done.

#2 'Just do it' in my humble but possibly very wrong opininon is a mistake. The guy is wanting to make a dedicated home theater and if that's his goal then slapping together his room without any thought is a mistake.

I'll admit maybe I'm a bonehead because I had a problem ceiling mounting the HD70 without keystoning (which I did not want to do), but when I see Galvatron post a similar thing at least I'm not totally out in left field. Having said that, that is also why I posted there are others here with greater experience. If you're on a budget and most do have to take in the WAF factor then it is a good idea to do your homework IMHO.

#3 I believe Budman is basically saying 'have fun this doesn't have to be rocket science' I would agree completely.

Was just making a point for vsreeniv that actually doing your homework which is the right way....sometimes, that he can use a low ceiling height and it will work.

I guess RWB i'm the one "flipping out"!

I started last fall with a sheet on the back of garage with a old optoma standup pj outside, to making a decent sports/movie hangout for me and my buddies.
My house is now the center for everyone to have a goodtime and we spent many nights doing so.
I have a 50"plasma in the living room...who cares thats for the women!!

I have 81" ceilings as well, even worse, my HD70 hangs from a 8" soffit. I tilt my projector up and use keystone. I really don't notice it that much. Besides, it works out nice with my anamorphic lens, because usually people suggest tipping them downward, now I can leave it flat and tilt the projector upwards.

hey budman like your set up cool im like u just set it up and enjoy

Thanks raiderdave007, i like it too, didnt spend too much money, 2 weeks ago got new furniture looking in the clearance floors, nice dark brown sofa for $299 and a berkline bronwn recliner for $159, had 30 yr old ancient herculon i got free 20 yrs ago...back breaker!!
Few yr's ago the place was a big storage mess,wife wanted to paint the brown paneling white...thank god i didn't!
It's nice to be down there, can really crank up the surround, i love concert dvd's have 100's of concert's, it's cool in the summer, total light control, added a dimmer to the ceiling light, got my beer fridge and i'm all set!!

My setup is in a 7' ceilinged basement HT.

The HD70 is 3.5" from the ceiling.
The screen is 11'10" from the PJ (lens to screen).
The screen is 100" diag.
The screen is 14" from the ceiling and 22" from the floor.
I use 0 keystoning.

I mounted the center channel speaker above the screen. (Athena speakers all around. ASC1: center - ASB1's left and right front - and ASIC8's {ceiling mounts} for surrounds) I had the center channel below the screen for years but it always seemed "too tight" and impractical. (And my size 14s on the ottoman could cause the center channel's speaker from having direct access to my ears.)
I have the side fronts mounted about middle high on each side of the screen, just above ear level.
I find the sound quite good this way. Most dialog in movies seems to come from the top half of the screen anyway. And putting the side speakers higher really seemed to let them "sing" I prefer the speakers to be slightly above the ear. And the center channel is aimed down at the listeners.
I like it. :D

Good luck vsreeniv! You'll enjoy the BIG show.

To vsreeniv, I do apologize for the bad advice because obviously several members here have had no problems in ceiling mounting. Maybe I was too lazy or to dim to think it out. As others have pointed out get ready for a lot of fun.

To vsreeniv, I do apologize for the bad advice because obviously several members here have had no problems in ceiling mounting. Maybe I was too lazy or to dim to think it out. As others have pointed out get ready for a lot of fun.

RWB.. I dont think you should feel bad.. this forum is a great learning place and I am always open to any suggestions...

btw.. i am getting my PMS mount from mountdirect in 2 days.. will let you all know how things progress. Also please note that the NPL mount from mountdirect has a 5" inch drop compared to the 3.25" drop of the PMS mount.

RWB.. I dont think you should feel bad.. this forum is a great learning place and I am always open to any suggestions...

btw.. i am getting my PMS mount from mountdirect in 2 days.. will let you all know how things progress. Also please note that the NPL mount from mountdirect has a 5" inch drop compared to the 3.25" drop of the PMS mount.


So how did everything turn out?