Axiom Home Page Forums General Discussion Home Theater high cost of anamorphic lens

Nick,

The problems with most 1080P projectors is lumen output, which is the reason high gain screens are becoming popular. Not many have much, or can compete with 720P units. Some are getting close though and I suspect in a year most will be on par. You want a minimum of 12 FL to give you that “POP” for movie watching and good shadow detail, and should up that number to 20 FL for sports. If you will have ambient light, then figure at least 15 FL and 23 FL respectively. Another consideration is projector rated lumens, which are always ridiculously generous. After the projector is calibrated to a D6500 standard, lumen output is drastically lower than rated output. Also figure a 50% loss within 500 hours of use and another 20% before it finally dies on you. My PT1000 for example has roughly 200 lumens after I calibrated it with 1200 hours on the bulb, but it’s rated much higher (900 or so I believe). I’m shooting onto a 96 X 41 2.35 screen. This equates to roughly 9.5 FL with my 1.3 gain screen. Figure another 10% loss shooting the beam through the anamorphic lens and I’m just over 8. That is a dim picture and I can’t stand to watch much of anything unless the room is completely dark. If I were using a screen with a gain of 3, my net FL would be about 19 FL and I could, if I want – watch movies with some light on. By having excess FL, you have many options available to you for really dialing in a perfect picture as well. ND or colored lenses for one. You also have plenty of wiggle room for bulb output fall off as more hours are put on it. If the picture is simply too bright, just use an ND lens and as the bulb dims, you ditch the lens.

So, yes, you are correct. High gain screens help compensate for projectors with low lumen output and are also desirable for set ups where ambient light is a problem or if you like to watch sports or movies with some light on.

In regards to improving contrast, gain doesn't help a whole lot. It allows you to run propper contrast / brightness controls without runing them to extreems for improved shadow detail. Silver and grey are great colors for screens because it enhances contrast and rejects ambient light, but typically, silver, and grey come with a penalty – they have a negative gain.

If you will be using a ‘smallish’ screen, the math will look much better for a projector with low lumen output. As the size increases, the math starts looking poor quickly. Another aspect is throw distance. If you are at the long end of the throw, lumen (reflected) output is reduced. The closer to the screen the projector is, the brighter the picture will be.

If you know exactly what the screen size is, lighting environment, room wall and ceiling color, throw distance and if sports will be watched……that will help determine what type of lumen output you need and if a high gain screen is needed or not.

More often the not though, a high gain screen is desirable. One drawback is they tend to have a narrow viewing cone or require the projector to be mounted in some odd angle or directly onto the screen. From what I've heard about the Prismasonic, they may have come up with a dandy. Definately worth looking at a little closer.

Good post...lots of good info. I'm new to this, so what's FL?

I am planning on a HT room in the basement in the future with a 110" screen. Not sure what the throw distance will be yet. I do want to be able to watch sports though. I'd want a 1080P projector as well.

Foot-lambert. Divide output lumens by screen square foot area.

So for sports viewing with some ambient light, I need 2530 lumens, correct? (23FL *110" screen)

So I need a projector that does roughly 850 lumens with a screen with a gain of 3?

The 850 would need to be the real lumens after factoring any loss for the throw. Can I easily measure how many lumens I'm actually getting?

I was going to ask about estimated costs for just these items, but I'm a little ways out on this, so I expect prices will continue to come down as the technology gets better.

mdrew,

You have been a big resource of information. I know that my dad will not spend $2000 to $7000 on a screen. I was reading reviews of the Planar on ultimateavmag.com and they were able to get 21.48fL in economy mode and 27.72fL in standard mode on an 87 inch 1.3 gain 16:9 screen after 30 hours on the lamp. The JVC RS1 was able to get 16.3fL in normal mode and 20fL in high lamp mode on a 78 inch 1.3 gain 16:9 screen with 200 hours on the lamp. He mentioned that the JVC RS2 was a bit dimmer than the RS1. So, you are probably right about having to use a grey high gain screen with the RS2. However, with the Planar I think that we will be fine with a 1.3 gain screen as long as the area of the 2.35 screen isn't much larger than the are of the 87 inch 16:9 screen. Even taking into account that after 500 hours on the lamp and using an anamorphic lens will drop the 27.72fL to 16.63fL (by taking 60%) which is still great. If I go to a 118x50 2.35 screen, which is about as large as he would go, then the 16.63fL is now 12.84fL.

I was leaning toward the JVC RS2 slightly over the Planar, but now the Planar looks like it would have the light output to aviod going with the high cost grey screens. I should be able to find a bulk roll of 1.3 gain screen material cheap, so everything is great. I just realized that if my dad will go about $10,000 for a projector and anamorphic lens then I am in the nieghborhood of the Runco with Cinewide. Now, I just have to narrow it down from the Planar, Marantz and Runco.

He already plans on darkening the room to watch the projector. But, what is the best color to paint the room to optimize the picture? I'd like to get this narrowed down before my step-mom picks out a color and then we are stuck.

- Nick

The best colour is as dark as you can go. The front wall should be black (ideally) to get no light bleedoff coming back at you.

I'll second Hutzal's recommendation. I noticed a huge difference in picture quality going from off white:



To black on the front wall and burgundy on the rest:

http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showgallery&Number=206049

(Plus, I think the room just looks nicer!)

Thanks Hutzal, I'll try to steer him in going as dark as possible.

- Nick

At least convince him to paint the front wall Black. The other walls can be another "darker" colour, but black (flat black, but a pain to work with) will provide the best result.

I just realized that I should have taken 40% of the 27.72fL to get around 11fL to take into account the 50% drop in brightness after 500 hours + 10% drop due to an anamorphic lens. So the largest I could go on a 1.3 gain screen is an 87 inch 16:9 screen with the Planar. I do want a 2.35 screen so I will need to make sure the area is not more than the area of the 87 inch 16:9 screen. I think even this will be fine since his front row will be about 10 to 12 feet from the front wall, so he will still have a very big screen for the front row. We are planning on him using the front row for blu-ray or high definition stuff and he can move to the 2nd row for standard definition stuff when he and my stepmom are watching it (which should be 90% of the time).

- Nick