Celling mount & gain

[R@p+0r]

Hello everyone I recently bought an infocus 4805, and now I have to buy the screen. I think i would buy a dalite hcwm 92'' (1.1 gain). Now i have this question:

-If I mount it on the celling, do i need an screen with more gain? the pj will lose some of the brithness?

-The room has a withe celling and light brown wall (it reflects a little of light), i'm planning to re paint all with a dark color.

btw, I own a dvd player pioneer 366 that has progresive scan. I read in many threads that i should send to the PJ an interlaced signal and let the work to the farajuda chip. I make a litle test and i noticed that the progresive signal was more bright and clear than the other one (keep in mind that this is a cheap dvd player) why could this be?

I have a dilema. I can buy a deluxe model b White Matte 92'' or a model b HC White Matte 92'', which is better? for the infocus 4805 ? HC will improve lumens?

Thanks a lot

[mvoorberg]

You wouldn't need any more gain for a ceiling mount. If a lightbulb is upside-down, is it any less bright?

When choosing a screen you need to consider throw distance, ambient light (windows etc) and the light reflected by the room. You already indicated that you'd be painting the room and ceiling darker so that should be ok.

-Mark

[Brandon B]

You wouldn't need any more gain for a ceiling mount. If a lightbulb is upside-down, is it any less bright?

While for the DaLite screen he has chosen, you are correct, this is not always the case. There are angular reflective high gain screens and retroreflective high gain screens. For the latter, ceiling mounting does indeed make the image dimmer.

It is odd the progressive signal looks better to you, and I don't have any handy explanation as to why that would be. But if it looks better to you, go with that. It may be that in a lower end DVD player, they figured people using the progressive output had decent HD TVs and people using nthe interlaced outputs have smaller crappier TVs, and just spend a little more design time and component cost making the picture quality higher when in progressive mode.

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[mvoorberg]

It seemed like such a simple question. I wasn't aware that high gain screens were that directional.

...learn something new every day!

[R@p+0r]

aha....nice point for mvoorberg.
which is the ideal position for mounting? if you ar measuring from the celling.

[Brandon B]

Retroreflective screens are a minority of the models available, but not that uncommon. My dalite highpower is one such.

Your ideal mounting height depends on the offset of your projector, that is the amount above or below the top edge of the screen the projector needs to be o shoot an undistorted picture a the screen.

I don't happen to know the offset for the 4805, but if you can turn it up somewhere, that will tell you how far from the ceiling you should be.

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[Dean McManis]

The High Power retroreflective screen would certainly be brighter with a ceiling mount, but if you have decent room light control, I think that the High Contrast Matte White is a better choice. The 4805's offset is 27.3%. Here's a calculator:

http://www.projectorcentral.com/InFocus_Home-ScreenPlay_4805-projection-calculator.htm

[Brandon B]

No, it is brighter with a table or low mount (unless you're sitting in a lifeguard chair).

Also, I wasn't recommending the highpower for his setup, I was giving it as an example of a screen where a ceiling mount would in fact mean less gain.

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[R@p+0r]

I have a dilema. I can buy a deluxe model b White Matte 92'' or a model b HC White Matte 92'', which is better? for the infocus 4805 ? HC will improve lumens?

[Brandon B]

Like Dean says, the HC is a good screen with that PJ. I would go with that.

Lumens are intrinisic to the PJ, and not affected by the screen.

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[BlazeMaster]

I'm faced with the same dilema also, but I've already had Da-Lite and Carada sending me material samples and my Chief mounts are on delievery to me and should be here early next week. The FP that I ended up with is the Optoma H-31, which is very comparable to the Infocus 4805, price and specs wise. Once the mount is finished, I'll know more about what angles I'm working with and using the samples I'll be able to make a better decision. Raptor, if you want I can shoot you a PM once I have the mounts finished and sample materials in hand.

One question for Dean and Brandon, is it an overkill to get a screen with a really high gain like the Vutec Silverstar (6.0 gain) for a DLP projector? I have decent light control during the day, would the 6.0 gain be blinding me when I watch it during night time with all lights completly off? I think the best way to describe the image that I'm looking to achieve with the screen is, something with more pop and more vibrant colors. I've heard that the Da-Lite High Power screens tends to create hot spots where as a higher end screen like the Silverstar is just smooth and bright all across.

[Dean McManis]

Everything that I've seen with really high gain screens have some sort of cost in picture quality. With a digital projector it's usually hot spotting, where the image is visibly brighter in the center, and shifts as you move your head.
If you have hot spotting on a lower gain screen, it will likely be worse with a MUCH higher gain screen. And also off-axis viewing will likely suffer as well.

You need to think about the percentage of viewing that you do during the day, as opposed to at night, and what sort of light control that you have during daytime.
If it's possible, I'd rather try to control the light leakage during the day, than to go with a super-high gain screen that will likely diminish picture quality the rest of the time.

You won't be blinded by a high gain image in a dark room, as our eyes compensate. But it's a bit like not wearing sunglasses outside on a bright, sunny day.
Your viewers will squint a lot during bright scenes.

[Brandon B]

I'd agree with all that for most high gain screens. Highpower is really not like that though. If you get up and walk to one side, you can see the image get dimmer, but it is not perceptible just moving your head. And there is really no sensation of hotspotting per se. If you look really carefully on a blank brightly lit screen, you can see a bit of nonuniformity in brightness (middle to edges if you are centered, side to side if you are not), but it is an overall gradient, not a small focused hot spot like you see with most high gain screens. I have not personally seen the Vutec. I have seen comments to the effect that it's gain is not a true 6 and is actually fairly comparable to the Highpower, but only a couple of times and I don't really have any verification for that.

It is not something that almost anyone would be able to detect in showing an actual image though. Also, even though off axis is dimmer, if you are dealing with a very bright image, it is still watchable. I would only worry about excessively dim images off axis if your PJ is not bright to begin with (i.e. 500 lumens or so).

I have not noticed anything about my image that dminishes the picture quality compared to lower gain screens, other than the extreme brightness of my image makes every shortcoming (MPEG artifacting, the VB and SDE of my projector, etc) plainly visible to me. However, I don't put those in the screen fault column as it is a choice I knowingly made, and since a better source and PJ would eliminate them.

I agree completely with Dean's last comment. Full daylight scenes absolutely cause an honest to goodness squint in my setup, especially where they follow a darker scene. When my lamp was new, in the center seat, I was at something significantly north of 100 Ft-L, and am probably still close to that. I actually enjoy this effect, though, as it adds an element of realism to films for me. YMMV and probably will. I would also add that some point out our eyes are more sensitive to subtle contrast differences when your pupils are more open (dimmer lighting). And my blacks are most certainly gray, not black. But to me, your whites would look grey.

I would also add emphasis to Dean's point about daylight vs. night viewing. I went with this setup originally as I have abysmal light control and no real way to rectify the situation, and thought this would allow me some viewing opportunities even if in a compromised way. What I found was that once I had an FP system, I was unwilling to make this compromise and always end up waiting until dark to watch. So the only time I avail myself of my system's high ambient capabilities is when we have guests for dinner, and it ends up being a mixed activity evening with some watching a DVD and some still at the table chatting with all the (recessed ceiling) lights on at the table in the same room. And usually only if I am not watching, as I hate the compromise.

So I would think long and hard if you will really use the high gain screen. If you conclude that is the direction you will go, I definitely recommend the DaLite screen. If you are looking at a rollup, mine has been pretty good about remaining relatively flat in the 2-1/2 years I've had it, and the material is also easily cleaned and does not show waves much at all.

In short, I am basically in the other camp, go bright. If I had the money, my next projector would be the twin lamp 3 DLP panasonic 7000. But I probably only run one lamp . So no, it's not overkill. If you subscribe to the position that SMPTE guidelines for brightness are the goal, and are trying to replicate the "film like" experience of a movie theater (or better as is often the case with a good HT), you will probably be annoyed by a high FtL setup with a high gain screen. I personally think that stems, in part at least, from the limitations on brightness placed on film projectors by the 48Hz flicker that becomes easily visible to many at anything over 25 FtL. I can see it at most theaters even at the levels they use now.

But if you are interested in a theater that can also be a more open environment with some ambient lighting at times, a high gain screen is great. It is more "giant TV-like" though. It can in a sense be more realistic, but it does not create the film-like effect many prefer. So figure out which sort you think you are.

If you think you might be in the L.A. area anytime soon, I can certainly give you a demo.

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[BlazeMaster]

well Brandon, I'm moving to the LA area this August, but I'm sure I'd bought the screen before I move down there. Can't wait to get the screen, I'll make a decision after I see the sample materials that I asked Da-Lite and Carada to send me. They should be here sometime this week. My mount will be here this Wednesday, spent a grip on the mounts, didn't know those things can get pretty expensive. Brandon, if you're still giving me that offer, I'd definitly take you up on it, during August, when I move to Rowland Heights. I've been to Dean's place before and very impressed with his setup.

My viewing environment, is not completly dark during the day, but it can get pretty close to it. I don't think I'll need the 6.0 gain screen, and kinda figured that it would make the image blindingly bright during the bright scenes. I think I'll go with somewhere in the 1.5 to 2.0 gain screen. What's the meaning of the "high contrast" screens? Do they increase the perceived contrast because they improve the brightness all together or the grey screens just make the blacks look more black, and sacrifice the brightness of the image to achieve this? Thanks Brandon and Dean.

[George Bellefontaine]

I once had a Vutec 4 gain screen that I really needed to give an old Sharpvision lcd projector ( the first one I owned, actually) some help in the brightness department. Very narrow viewing cone and looked ok with the Sharp but tried using it with a Zenith crt I upgraded to and YUCK. Since then I have pretty much stayed with 1 gain screens, and they work well with what I own now, an NEC HT1000 dlp and a Yamaha LPX 510 lcd, but I have a dedicated room with no windows.

[Brandon B]

Offers certainly still open in August, but it doesn't get dark until 9pm then.

Dean's setup is certainly more impressive than mine, better DVD deck, better projector, better environment. But if you want to see what light cannon plus high gain screen can do, mine's the house to come to.

Dalite actually has a decent little tutorial on screens on their site. It is obviously geared towards selecting one of their products, but there is some good general info as well, if you decide to go with a Carada or other screen.

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