Final questions on a new set up

[Ace in the hole]

We are finally going to install a projection system in our church.
Our set up- 50' throw to screen, 70' from screen to back pew. light at screen location is 16fc on a bright sunny day because of skylights. It is slightly controllable, we can get it down to 13-14fc dimming some lights.
Our committee has decided to go with a recommendation from one company for the equipment and do a self install.

The equipment:
mac computer running propresenter
matrox mxo box to convert computer signal to sdi
sdi cable up to projector location and fed into an aja sdi to hdmi converter
a panassonic pt-dw730 projector 7000lm 1280x800
a 87"x139" (164" dia) stewart screen using the ultramatte 150 material, 1.5 gain


this is the basic system we are going with for now but there are people who are pushing for a confidence monitor too. It will not be long before we install one. We are looking at a sharp 70" tv mounted fairly close to the projector location. This would make it 40' plus or minus from where people would be reading it. My questions are-

if we go with that location can I just use an hdmi distribution amp after the aja converter and then run one cable to the projector and one to the tv?

How about glare from the projector, will it be an issue having a confidence monitor close to the projector?

THANKS IN ADVANCE FOR ANY INPUT.

[petereit]

You could do your confidence monitor that way, but it's not the best because it limits your confidence display to exactly what your congregation sees.

If you run a separate signal, you can use ProPresenter's fold back display feature to drive your confidence monitor which gives your singers the benefit of being able to see the next slide's lyrics before they're displayed to the congregation. It also let's you display sermon notes, clocks, timers and ad-hoc messages to your pastor while he's preaching (Wrap it up! Kickoff in :30!)

[Brad Weber]

Originally Posted by Ace in the hole

We are finally going to install a projection system in our church.
Our set up- 50' throw to screen, 70' from screen to back pew. light at screen location is 16fc on a bright sunny day because of skylights. It is slightly controllable, we can get it down to 13-14fc dimming some lights.
Our committee has decided to go with a recommendation from one company for the equipment and do a self install.

The equipment:
mac computer running propresenter
matrox mxo box to convert computer signal to sdi
sdi cable up to projector location and fed into an aja sdi to hdmi converter
a panassonic pt-dw730 projector 7000lm 1280x800
a 87"x139" (164" dia) stewart screen using the ultramatte 150 material, 1.5 gain

I'm not sure I understand the purpose of the Matrox box or combining it with the 16:10 projector and screen. Like many video oriented devices the Matrox MXO seems to support only video type signals, e.g. NTSC/PAL SD (720x486/720x576) or 720p and 1080i HD (1280x720 and 1920x1080 respectively), so none of those match the native 1280x800 resolution of the projector or 16:10 format of the screen. Thus you seem to have a 1280x800 projector and 16x10 screen but would have a source that is limited to outputting a 1280x720 or 1920x1080, 16:9 format signal on the SDI output.

An 87"x139" screen equates to a 9.655:1 ratio for the most distant viewer to the screen height. Displaying a 16:9 image the ratio would be higher. That is a bit higher than recommended but not out of the question in terms of potentially being acceptable.

With that screen size you'd have 83.35 ft-L hitting the screen from 7,000 lumens. With 16fc of ambient light that 83.35 ft-L equates to a 5.2:1 image contrast ratio and with 13fc a 6.4 image contrast ratio, both below the 10:1 traditionally suggested and 15:1 currently recommended but probably usable. However, with the 50' throw distance you 'd need the optional 3.8-5.7:1 long throw zoom lens, which would likely result in slightly reduced output. So anything you can do to reduce the ambient light on the screen would probably be recommended.

[petereit]

Matrox box makes perfect sense: deliver a rock-solid digital signal as far as it needs to go without any signal loss or RFI issues. Exactly how we're set up and it looks spectacular!

[Ace in the hole]

Thanks for the replies.
Brad- I appreciate your input, you have some valid issues. I realize we are on the edge as far as recommended sizing and brightness but this was our best set up for our budget. We downsized the screen a little to help with the brightness/light issue. The projector calculator on projector central is giving us numbers closer to 100fL on the screen. The mxo is only to make the signal sdi. I never thought about the mismatch of outputs but shouldn't 1280x800 to 1280x720 still give a nice picture? We currently have sdi cable that is available to us so thats what we wanted to use. If you have another solution to get the signal to the projector over sdi cable without signal mismatch, I would gladly entertain the thought of different equipment.

Mark, thank you too for your thoughts. If we have enough cable I may run a second line up for future use but here too, budget comes to mind and I think the people pushing for the monitor are only expecting to put up a mirror of the main screen so it should not be a big deal.

[tdangelo]

Originally Posted by Ace in the hole

50' throw to screen, light at screen location is 16fc on a bright sunny day, we can get it down to 13-14fc dimming some lights, panassonic pt-dw730 projector 7000lm, 87"x139" (164" dia) stewart screen using the ultramatte 150 material, 1.5 gain

Ace,

Stewarts website has a really good spreadsheet you should take a look at:

http://www.stewartfilmscreen.com/res...sidential.html

If I inputted your data correctly you will only achieve a contrast ratio 9.5:1. Typical acceptable contrast ranges for house of worship are between 18:1 - 40:1. Entertainment venues would have a contrast ratio range of 50:1 - 150:1.

[Ace in the hole]

WOW, nice spread sheet. I get the same values as you. It looks like Stewart would not recommend using ultra matte 150. We have not purchased anything yet, I am going to raise this question to the company.

[Brad Weber]

Originally Posted by petereit

Matrox box makes perfect sense: deliver a rock-solid digital signal as far as it needs to go without any signal loss or RFI issues. Exactly how we're set up and it looks spectacular!

It may make sense in some applications, but when I see a system that is apparently simply a computer output to a 1280x800, 16:10 projector then I don't see a $1,000 box at the computer and a $490 box at the projector being required. Maybe the MXO is also splitting the signal to a local DVI monitor or the SDI out of the MXO is actually going into a SDI based production system or there is something else involved that has not been noted, but it seems an odd approach for simply getting the computer output to that projector.

1280x720 will map nicely to a native 1280x800 projector, but would mean that due to the slight letterboxing at the top and bottom then instead of a 139"x87" image and 7,000 lumen projector you would be looking at a 139" wide x 78" high image and an effective 6,290 lumen projector. The other option would be to have the projector remap the 1280x720 signal to 1280x800, which would fill the screen but cause the image to be slightly vertically stretched and would not be direct 'pixel to pixel' mapping.

The suggested contrast ratio of 18:1 to 40:1 for worship spaces may be a good goal but is impractical for many churches and well above what is considered acceptable in many existing church applications. At some point there is an image brightness that is actually too bright for comfortable viewing and thus it is not always practical to overcome higher ambient light levels and obtain the ideal image contrast by projecting a brighter image.

[Ace in the hole]

Originally Posted by Brad Weber

The suggested contrast ratio of 18:1 to 40:1 for worship spaces may be a good goal but is impractical for many churches and well above what is considered acceptable in many existing church applications. At some point there is an image brightness that is actually too bright for comfortable viewing and thus it is not always practical to overcome higher ambient light levels and obtain the ideal image contrast by projecting a brighter image.

Good point, but that leads me to another question- would a different screen material that offers better contrast, even though it is not as bright an image, offer a better picture?
A lot of screens that offer better contrast also have reduced viewing angle. Our set up really needs at least a 50 degree viewing angle so this also limits our choices. We have also looked at doing something to our skylights to reduce the light and this still will happen- just not right away.

[tdangelo]

Contrast ratio and brightness are both important factors.

Let me use a PA system analogy: brightness would be how loud the PA system could go. Or, what is the maximum SPL (sound pressure level) is. Contrast ratio on the other hand is very different. In a PA system it would be equivalent to how many times louder might the loudest sound be when compared to the quitest sound (above noise floor). Both are essential. If the PA system is capable of amplifying a sound to 120 dB SPL, that might be great, but you wouldn’t want ALL sounds to be at 120 dB SPL. You may want announcements to be at 70 dB SPL, or a flute solo at 80 dB SPL and an ear bleeding guitar solo at 110 dB SPL. The ability to have a wide range of volumes is your contrast ratio.

One might assume that the brightest image would also be the one with the greatest contrast ratio, but that is not always the case. We’ve all seen projection before where the whites read (where visible ok) but the blacks all looked grey and the greys, well looked white. That’s because the projector (and/or screen) where not capable of enough contrast … not because the screen wasn’t bright enough.

[Brad Weber]

Originally Posted by Ace in the hole

Good point, but that leads me to another question- would a different screen material that offers better contrast, even though it is not as bright an image, offer a better picture?
A lot of screens that offer better contrast also have reduced viewing angle. Our set up really needs at least a 50 degree viewing angle so this also limits our choices. We have also looked at doing something to our skylights to reduce the light and this still will happen- just not right away.

In general, I like some of the high contrast screens in applications where ambient light levels will be high. For many sources I find that improving the image contrast makes the image seem brighter even if the peak white levels remain the same or even slightly reduced. However, some people have a problem with the visual appearance of a grey rather than white screen surface when the screen is not in use, including some churches who have gone to great lengths to have all the other room finishes be white.

Another factor in the screen selection is screen gain. Gain is basically how the screen surface material focuses the light hitting it back into a more controlled area and thus increases the light reflected to the viewers. Typically greater gain equates to a narrower viewing angle, but also keep in mind that the gain affects not just the light from the projector but also any light hitting the screen. So while a higher gain screen increases the brightness perceived from the projector, it may not significantly impact the image contrast as to a great degree the gain affects both the projected image and the ambient light. Thus if you need a brighter image a brighter projector may be preferable to a higher screen gain as increasing the projected image brightness without increasing the screen gain would also improve the image contrast ratio.

[Ace in the hole]

Thanks for the explanations. I understand gain. Thats on reason I think they recommended the ultra matte 150 material, 1.5 gain but still a nice wide viewing angle. It should help brighten the image. Playing around with the spreadsheet above it appears that Stewart would not recommend the ultra matte 150 unless you hit it with 12k lumens in our situation.
Our church is set up such that we need a wide viewing angle, somewhere around 100 to 120 degrees, and that really limited us for screen options. I know there are screens out there that would give us better contrast but the specs on all the ones I looked at had a half gain angle that was too small for us. Unless someone can come up with a better option we more than likely will stay with the stewart screen. We will eventually be doing something with our skylights to help with the ambient light level but it may be a year or two before that money is available. We also need to keep in mind that the 16 or so fc at the screen are a worst case scenario, cloudless sunny day in mid summer. Most of the time we will have less, cloudy days or lower sun angle during winter.