Originally Posted by Nedtsc
Would you guys agree with Chris assessment on HP ?
I haven't seen any reports of problems with sparklies. Here is some objective data from Glen C on the HP versus Studio Tek, Firehawk, and Carada BW. I can't find original post, but this is what I saved from it:
"You also mentioned your tight budget. In a fixed frame, the Carada BW is one of the few screens that comes close to fitting in your budget. It is rated at 1.4 gain. I have measured this screen with my spectroradiometer. With a ceiling mounted PJ, I measure it at 1.1 gain. It has exceptional color accuracy, and brightness and color uniformity. It's velvet lined frame is equal in size and beauty to my Stewart screen. It is simple to install. One caveat: its high uniformity is a disadvantage in a room with white ceiling and walls. (In this case, I would recommend the Stewart Firehawk, which is triple the price.)
Another screen that is near your budget is the Da-Lite High Power, rated at 2.8 gain with a shelf mounted PJ. When coupled with a ceiling mounted PJ (mounted 16% the screen's height above the screen surface) I measure it at 1.17 gain, but this is going to vary depending on how high/low you mount it. It is available in fixed screen or pull-down. It is acceptably color accurate. It is almost perfect in terms of color and brightness uniformity. It has a wide viewing cone. The folks that have posted contradictory statements regarding its uniformity in the configuration that I have listed, are just flat out ignorant about this screen. I challenge them to back up their statements with facts by listing the measurements they have taken of this screen with a ceiling mounted PJ. (Don't forget to measure the PJ's uniformity first, so that you can subtract it from your screen measurements.)
Some folks have reported an occasional sparkly on the HP. I don't know. Typically a sparkly will disappear from view if you shift your seating (or your head) to the side by an inch or less. The Firehawk is known to have this problem occasionally, and I have seen iton my own screen. I have read recommendations to color them over with a soft lead pencil on the Firehawk, but have never had cause to do this personally. As far as eliminating them on the HP, Da-Lite may have some recommendations. I don't know.
SCREEN_____GAIN AT________REDUCTION AT___SCREEN CENTER FROM
___________SCREEN CENTER__SCREEN EDGE___SEAT AT 45% ANGLE
Measured color shift in x/y imparted by the screen measured at the same positions listed above for uniformity.
SCREEN___COLOR SHIFT AT___COLOR SHIFT AT__COLOR SHIFT FROM
_________SCREEN CENTER___SCREEN EDGE_____SEAT AT 45% ANGLE
Studio Tek 130, Carada Brilliant White, Da-lite High Power, Vutec , Firehawk.
In a white room the Firehawk will stomp the Carada and any other screen like it. The Firehawks defects work to give it a higher on-screen CR, because it dampens cross-light reflections. The difference is quite visible and vastly outwiegh its dissadvantages.
In a theater with dark or non-reflective surfaces, I would use a screen with better uniformity. However, I see quite a few black-hole theaters that use the Firehawk and it still looks great. I just think that there are better choices. Not everyone agrees with me about this. I have friends who think their Firehawks are better than white screens even in their black-hole theaters. IMO, in such a theater there are minimal cross-light reflections to wash out the screen image. So you don't need a Firehawk. No screen can change the CR of an image on its own. It is only by dampening the effect of cross-light reflections that the on-screen CR can be affected. Other than that, grey screens have no affect on CR, despite what some may post. A lower gain screen lowers the level of White to the same degree as it lowers the level of Black and CR remains the same, just at a lower level of brightness.
There is a ton of BS about screens on the forum and in print. A screen is mearly a reflective surface. What it does to any image reflected from it can be measured in terms of color shift and brightness shifts. Plus the affect of the surface texture on sharpness, sparklies, and the like.
Though the Firehawk has slightly higher gain at the very center of the screen, it measures lower and lower gain as you move out from the center towards the sides. The Carada remains much more constant. The Carada would probably appear brighter over all than the Firehawk because of this. I usually figure the Firehawk at 1.0 gain when planning how bright a PJ to mate with it.
White vs Grey in itself has absolutely nothing to do with "POP" or color purity or anything like that. This is a lack of understanding as to what is really going on in the reflected image. In video, grey is the same color as white. It is just less intense (less bright). In video, White and every shade of Grey is the color described by the x/y color coordinates .3127/.3290. When an ISF calibrates a display's greyscale, he sets the display so that White and every shade of Grey down to Black is as close to .3127/.3290 as possible. If a screen is color accurate, meaning that it does not impart a color of its own to the images it reflects then it doen't matter what that screen looks like when the PJ is shut down and the room lights are on. The screen can look white, grey, and even a little salmon color and still be shown to impart no significant color shift. You can't judge a screen with the room lights on.
Where this POP thing comes from is that people have compared higher gain white screens like an ST130 to lower gain grey screens like the Firehawk in the same room and at the same time. In this kind of comparison the dimmer screen looks greyer. However, from reading the above, you probably realize that looking "greyer" only means "dimmer" in this context. If you bring in say a 1.8 gain white screen and put it next to the ST130, now all of the sudden, the ST130's image looks greyer and lacking in POP. Remove the 1.8 gain screen and the ST130's POP returns. Now remove the ST130 and the Firehawks vividness returns. And so on and so on and so on.
This is just the way human vision works and this is well known. For example, if you project a white square that is 10 fL against a Black background, you will see the square as being White. Now add a second square next to it that is 12 fL. The 10 fL square suddenly is perceived as being light grey.
The Carada has advantages over the Firehawk in terms of superior uniformity, both in brightness and in color. However. any differences in "perceived" color vividness can only be due to differences in brightness. Make it so that the image coming from the Firehawk is brighter, and then it will appear to be the more vivid in a side by side comparison. On their own, without direct comparison, both screens will be equally "vivid". Anyone who thinks otherwise is mearly fooling themselves.
Let me put it another way, as long as two screens do not color shift the image, the colors they reflect will be identical escept for how bright they are. Neither one will be more "vivid" than the other. In an HT we are selecting a PJ and screen to achieve a certain desired brightness level, which is commonly 12 fL at White. The size and gain of the screen will determine how bright it is. Choose a screen whose gain gets you your desired brightness level.
Yes, a grey screen will look identical to a white screen that has the same gain and uniformity charectoristics. You could not tell the difference, nor could measuring equipment. Anyone who tells me they see something that can be demonstrate is not there, is merely mistaken.
With the caveat that there will be some differences if the two screens differ in brightness uniformity. The measurements that I posted for intensity at the edge of the screen when measured from the prime seat describe how uniform the reflected image will be to the prime seat. Keep in mind that that for the human eye/brain to sense that brightness has been halved, it must actually be reduced to 18% of the original intensity. The human eye/brain senses that the change in intensity is much smaller than what the meter does. This coupled with the fact that most video images are not uniform themselves makes people surprisingly tolerant of brightness uniformity issues like those induced by the Firehawk, for example. So I say, "Yes". If you want a big screen, and that requires using a gain screen. Go for it. You can also choose to go the lower gain and smaller screen route and move the seating closer as an alternative. The measurements for intensity when measured from a seat set at a 45 degree angle from the center of the screen describe how much dimmer the image will appear to someone sitting off to the side at a 45 degree angle. If you don't have seating off to the side, then this isn't of concern. Most HTs don't. If you do, then that non-uniform screen might not work well enough for you. It all depends on how often those seats get used and how important that is to you. I actually have seats in my HT at that angle, and guests choose to use them instead of sitting in front of the screen frequently, and to my consternation, because I never would. They find the brightness level from those seats OK.
Another example. I put in a theater that also had seating off to the sides and where the intended audience would be critical viewers. I wanted to use the Carada BW because of its uniformity and because of its low cost. The screen needed to be large. I could not use the 122"D screen that I wanted. It would not be bright enough. I settled for a 110"D screen and moved the seating closer to the screen to maintain the same field of view for the prime seat. The walls were dark and non-reflective, but the ceiling was white. I can see visible image washout from the cross-light reflections off the ceiling. It still looks very good, but it will look even better if the ceiling is darkened. In this room a Firehawk would look better to a viewer in the prime seat than the Carada does, but the viewers on the sides would see a considerably dimmer image and they would probably disagree, at least I think I would."