John*DB

Math questions for ya. I don't mind doing the math myself if someone wants to tell me how.

How high can my 4805 sit (on a stand...not ceiling mounted with inverted view) with a ceiling that is 7'10"?

I cannot ceiling mount this so I have to figure out how high I sit the proj behind the couch so the couch back and viewers heads are not in the way of the image...no shadow puppets or MST3000 impersonations in my house!!

Oh yeah...projector will be 14 ft from screen

John*DB

I have a reeeeal good feeling I am going to have to put this projector upside down (but not mounted) and invert the image. I think the image will throw too high at 13-14 feet back at 4-4.5 feet high with an 8 foot high ceiling.

Soooooooo.... NOW my question is, if I SIT the PJ on its TOP and switch to ceiling mount view...

Will that affect ventilation or any thing else since "it is not designed to do that"

The image is what I will almost definitely use.

Jack Gilvey

What size image? The lens will need to be either approximately 1 foot above the top or 1 foot below the bottom of the image.

Try the projection calculator on this page .

John*DB

I have used thc calculator many times. It does nothing to explain the offset or help you configure the height of the 4805 with an offset (of what I have gathered) to be 127%.

The height of my image will be between 3.4 and 4 feet. But I need to calculations of how to figure out pj height. Where does the "1 foot" come from?

Jack Gilvey

You input your desired screen width and it tells you exactly how much offset there will be. If you know where your screen will be, you know know where to put the pj. If you know where your pj will be, you know where your image is. Not sure what you're looking for beyond that.


Ok...let's say you have a 70"x39" image...80" diagonal. Your offset, from the center of the lens, will be 11".


Your "calculation" would be to add 11" to the desired top of the image to get the height of the lens.

John*DB

Edit!! I just realized the link you have me was not the regular calculator...its an excel program.

Might have questions about this one too though.

Thanks you for the link!!

John*DB

The problem is I can only change the yellow box. I want to change the projector height!

I want to know where my screen would need to go if I had my pj at 6 or 6.5 feet w/ a 16:9 screen w/ 92" diagnol.

Jack Gilvey

For a 92' diagonal image, it shows the offset to be 1.04'. So, the difference in height, the drop, from the center of the lens to the top of the image is 1.04'. Subtract 1.04' from the height the pj lens to find where the top of the image will be. The diagram is useful.

John*DB

gotcha