Quote:
Originally Posted by
AV Science Sales 4 
There is a lot of babble here about screen gains.
Jeeze, I hope that's not directed at folks like me. A lot of us here try to be careful and consciencious in evaluating these things and expressing our experiences. I don't think anything I wrote concerning my experience with screens of varying gain was off the mark.
Quote:
Originally Posted by
AV Science Sales 4 
I will be chasnging out my Studeotec 130 GII to the latest Studeotec 100.
Just curious: Why?
I have the StudioTek-130 G3 and love it. However, I like the idea of a screen that is as "invisible" as possible, so the ST-100 intrigues me.
What's your reason for moving to the ST-100?
Quote:
Originally Posted by
AV Science Sales 4 
Please remember the larger the gain, the further must be your throw to avoid hotspotting on the Stewart 1.5 gain and 1.7 gain. Studeoteck 130 gain was set in the old days using the highest gain that could be used the throw ratio CRT FPs were set up at and not hotspot. Joe Kane who was involved in the screen material design wanted gain, a fairly wide half gain angle, and no hotspotting.
Most digital projectors with zoom lens have minimum throws above 1.3 and hotspotting will not be an issue bwith gains say 1.3 and below.
(Emphasis mine).
Mark, I see such comments about screen gain/hotspotting a lot, even from experienced installers. But I suggest we need to be even more careful about making such statements (for the sake of accuracy and education).
The problem I find in what you wrote is there is no distinction raised between the
manufacturer rated gain of the screens and the application of optical coating used to raise screen gain (e.g. the actual characteristics of a screen).
Your post implies, even if you didn't mean it to, that one can look at the rated gain of a screen as an indication of whether hot-spotting will be more likely or not. But that would be really misleading. The tendency to hotspot isn't tied to gain rating per se, but to the amount and type of optical gain coating used on a screen.
Take the Stewart Firehawk G3 vs the Stewart ST-130 screen material. The Firehawk is rated at 1.25 gain, and the Studiotek is rated at a higher 1.3 gain. If we were to infer simply from screen gain numbers, one would conclude the ST-130 would hotspot more, and perhaps have more screen texture. But it's the reverse. The lower-rated-gain Firehawk is the one that sparkles more and hotspots MUCH more visibly. Why? Because it starts out with a darker screen substrate - gray vs white - and is made to handle room reflections/ambient light more aggressively - while also needing to raise brightness to acceptable levels from the viewing angle - so the optical coating is applied much more "aggressively" on the Firehawk, resulting in
much more hotspotting, more screen sparklies, and much more drop off of brightness off-axis.
Taking it further, look at the Black Diamond screens .8 gain screen. Going by gain numbers you'd never know that this screen has very visible texture and hotspots WAY more then most white screens, including higher gain white screens. Again, this is because hotspotting/screen texture isn't related to a higher gain screen rating, but it tied to how aggressively the optical coating is used. The BD screen starts with such an insanely dark substrate (to kill ambient light reflections) that optical coating gain must be applied aggressively to get the image to acceptable brightness to the on-axis viewer. The JK screen, rated at almost the same gain, or a neutral gain screen, or the higher gain ST-130 screen, won't hot-spot anything like the BD screen.
So statements like
Most digital projectors with zoom lens have minimum throws above 1.3 and hotspotting will not be an issue bwith gains say 1.3 and below could be seriously misleading to someone who doesn't know better.
No doubt you know all this. But if we are looking to make sure our information isn't ambiguous, I figured these comments were apropos of our trying to be accurate in discussing screen characteristics.
Cheers,