Projector Help Needed

[steelhead]

Hi,

Looking for advice regarding projector location for a golf simulator I'm planning. I'll be using a 9x12 enclosure, 4:3 aspect ratio. The viewable screen is 136" wide by 102" in height. The bottom of the viewable screen is about 5" off of the floor and there's another 5" of space above the top of the viewable screen. The enclosure will project towards the hitting area by 5 feet. The hitting area is 12 feet from the screen.

As an example, I punched in the Optoma GT1090HDRx projector into Projector Central. I chose 4:3 aspect ratio, 171" diagonal and ceiling mount. This gives me a vertical offset of -16". Does this mean that the center of the projector lense needs to be 16 inches above the top of the screen. With a throw distance of 7'-7", I'm a little concerned that the enclosure frame will interfere with the image projection.

Another option I chose was the Benq TH671ST. With all of the same parameters as above, this gives me a vertical offset of -3" and a throw distance ranging from 10'-6" to 12'-8". This vertical offset doesn't scare me since there's a 5" space above the viewable screen. This leads me to my other question.... how far behind the hitting spot of 12' can I mount the front of the projector?? I don't see a foot or two beyond as a concern because the projector will be ceiling mounted. Is it possible to mount the front of the projector 3, 4, 5 or even 6' behind?? I definitely do not want to cast a shadow onto the screen.

Am I understanding all of this correctly?? Any input would be greatly appreciated.

[preludesam]

The negative number means above the top of the image.

As far as the location and shadows don’t worry it won’t cast on either of those projectors. I have similar screen dimensions and I get no shadows until you’re like five feet from the screen. The best position for it is directly over you ball location. It’s almost impossible to damage it right over the ball.

I have a Benq TH671ST it works fairly well as long as you can control the ambient lighting especially any lighting behind the screen.

[steelhead]

So preludesam, if I'm understanding you correctly, the projector lense would need to be located approximately 16 inches BELOW the top of the screen??

There are a couple other projector options where the lense would be located 16 to 17 feet from the screen, which would be 4 to 5 feet behind my ball location. I was wondering if shadows might come into play.

I was also looking at the TH671ST as that would put the projector 10'6" to 12'-7" from the screen...basically over my ball. I was concerned about the brightness, however. I'll have it in a garage with no windows. I was thinking about turning off the lights and/or dimming them and adding a pin spot light. I think it would be fine from a brightness standpoint but not 100% sure.

If I go with a projector with a throw of .5 as in the example above, I think it would work fine and hitting the projector with a golf ball or club would be difficult. I'd probably still add some type of protective cage.

I greatly appreciate your input and advice!

[stubious]

negative numbers mean above the screen if ceiling mounted or below the screen if floor mounted
edit: I'm saying that based on projector central specifically - I've seen it used as both positive and negative use cases, which adds to the confusion, but take these two examples:

1. Large positive offset - projector is clearly in the middle of the image: https://www.projectorcentral.com/Pan...-PT-VZ580U.htm
2. Negative offset - projector is clearly below the image (and if you tick the 'ceiling mounted' checkbox, it is above the image) https://www.projectorcentral.com/Opt...r-pro.htm#calc

I've been investigating a similar setup for a room with a very short ceiling (8'5") and to get max image height, the benQ is better due to the lower distance above the screen that is required (assuming the throw distance works for you). That being said, you could mount the Optoma with less clearance to the screen, tilt it slightly and fix it the image shape (now a trapezoid due to it the angle, the unit is not square to the screen) with keystone. Keystone is a digital correction, so will slightly impact image quality.

I built a little calculator for my use case to calculate max image height based on my ceiling height, projector mount depth, vertical offset for my projector and assumed gap from the floor to start of image. I could get a 'taller' image if I used less vertical offset, angled the projector slightly and fixed in keystone. I may play with that once the projector is mounted, but wanted to understand my 'worst case' image height.

I went with the Optoma over the benq as I've got some throw distance constraints and am going to be hitting from 7 feet or so from the screen. But with your setup (ignoring differences in projector imaages), I think the benq is better with the shorter offset.

[stubious]

Version of the spreadsheet in google sheets, here. You can make your own copy in order to edit it with your details. Feedback welcome!

[wbond]

The optoma will be way above the top of the screen. i have the GT1080 and it has the same dimensions. I specifically went with this over the Benq because it gets it higher away from the golfer and i have a higher ceiling. If you don't have a high ceiling i wouldn't go with the optoma unless you angle it and then you could possibly have image degradation due to needing keystone correction to fix the skewed image.

[steelhead]

@preludesam.... thanks for the update and clarification!

@stubious...nicely done with the spreadsheet! I think the benq th671 will be better as well given the much less vertical offset required.

@wbond...I'm not sure if the GT1090 will work (more below on that) and I appreciate your input.

@everyone! See attachment. It's a side view sketch using the GT1090 as an example. Each block represents 2 inches. Using the knowns of: 1.) 7'-7" throw distance for my 4:3 171" diagonal impact screen, 2.) projector vertical offset of -16" (which we now understand is above the top of the screen haha), 3.) the frame of my simulator projects 5 feet out from the screen position, 4.) the impact screen sits approximately 5 inches below the frame.

From this scale drawing, it appears there's no way the projector image will all make it to the impact screen. I'm pretty sure some of the image will be blocked by the impact screen frame. Someone tell me I'm not crazy!! I don't think it'll be even close. Thoughts/opinions??

IMG_1211.pdf

[wbond]

You're correct, that image with the optoma is going to get cut off. I can tell you, i have my ceiling protection angled and the optoma slightly hits that.

[stubious]

yeah, that's an issue. Either you need your frame closer to the ceiling or the projector lowered down (e.g., benq). Or you do away with the projecting top of the frame and do foam panels or something on the ceiling.

[steelhead]

That's what I thought, thanks stubious!

The Benq TH671ST is the best option for me. I just wish it had more lumens. Mounting the center of the lense 3" above the viewable screen line will put it right about 8'-8" off the floor. With it being over the ball impact area, I have no concerns with hitting it (ball or club).