AVS Forum Club Gold
Join Date: Sep 1999
Location: Alexandria, VA
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Thanks for responding to my message. I wasn't sure if you would be checking your PM's on the forum or not. I will try to answer your questions to the best of my ability.
As for replacing the screen on your Mits rp unit, I think we can help. Sometime ago, HT mag did an article on doing just what you are wanting to do and they used a Da-Lite screen for replacement. There are two ways of doing what you want. The first is to provide you with a plex panel that is either 1/8" or 1/4", as specified by the lenticular layer that Mits uses on their screens, and then replacing just that unit and keeping your current fresnel. That is the least costly way to go. The other way as you requested is to simple replace the whole element with one of our Polacoat Ultra screens. Either way you go the result is the same, it may just depend on the thickness of the current unit and a few other factors. At this point, please allow me to answer your questions.
1) By what factor does the diffusion screen decrease perceived light output? My Mits is in a 'home theater' setting with good control over ambient lighting. BTW, the 7" guns produce a very bright picture.
Actually our diffusion layer does not reduce the light output it just directs it very differently than the current Fresnel/Lent design of your set. You see the unit you have in the set probably has a gain of about 4.0 and every other line in the lenticular layer is painted black. This it to help with ambient light rejection. Also the horizontal half angle of the screen you have currently is probably about 41 degrees and the vertical half angle is 12 degrees. I am sure you have noticed that if you stand up or sit down the image goes away and comes back. What we can do with our diffusion screens is to provide them with a number of gain factors. What we do is simply either take out diffusion elements to increase the gain or add more to decrease the gain. Therefore, you will notice a difference in the perceived brightness if we go to something like a 1.0 or 1.5 gain screen (which is what most people go with). However, the increased resolution is a big factor and usually wins out over the loss in brightness. I might also add that the viewing half angle (both horizontally and vertically) is more like 55 degrees with the diffusion coating. That is why its gain is 1.0, it disperses the light more evenly than the black stripe that is currently in your set.
As you stated, you have good ambient light control over your room. If you are looking to make your set perform as good as it can without having the screen do anything to the image, the best way to go is the Video Vision coating. Video Vision is ISF certified and is what most enthusiast put in their RP units. The coating is milky white in color, so that it does not push one color over another.
2) What is the thickness of the replacement screen? It will be mounted in the existing frame.
If you decide to keep your current fresnel lens, we can use either a 1/16" of 1/8" plex that will closely match the lenticular layer of your current screen. Otherwise, if the Ultra is your choice, it is 1/4" thick. Also, we will coat the plex all the way to the edge to accommodate for the small amount of frame that most manufactures provide.
3) What is the pitch of the screen? I'd like a finer pitch than I have now.
This is a bit of a tough question in one regard. That is the fact that the diffusion screen does not have a pitch. When you look at the screen all you see is a smooth coating, therefore it has no ridges to create a pitch. However, if you decide to go to the Ultra, the fresnel has a pitch of 0.19 mm. I would imagine that the pitch of your current fresnel is very similar to that but I am not sure. Even if it is not the fresnel pitch has very little affect on the image resolution, the front layer is what determines the resolution.
4) I know this is not a cheap solution, but I'm more than willing to pay for an improvement in the picture. What is your guarantee for performance?
You are correct, this is not a cheap endeavor. This is a really tough question because there is not true way to A/B the two types. In other words, Yes, I know the picture will look better, but will you think the same thing? That is a tough one. I can guarantee that you will see better resolution, but as I stated earlier if you are looking for the image to be as bright as it is now in the "sweet spot" you may be disappointed. It will not be as bright but the image will be more uniform, higher resolution and will have truer color (especially if it is ISF calibrated). Anyway, we do allow customers to return product if they don't like them, but there is normally a 15% restocking fee on custom products and this would be one.
I hope these answers will help you. I want to make sure that you understand all there is to know about this process to help you make a decision. Off the record, it sounds like you are a fairly true enthusiast and perfect image quality is key to your set up, having said that I think you will appreciate the change that the diffusion retro will provide. Changing the screen in your set is very easy and for the true enthusiast there is no better picture than a Video Vision diffusion screen with the fresnel lens from their old screen. However, I do want to add that it needs to be used in a room that is virtually dark.
If you decide to go with the change out, I will need to get the dimension of your current screen. That may involve taking the front cover off and measuring the dimensions including the thickness of the lenticular layer and any others except for the fresnel. From that we can provide you with a matching size and the swap out is easy.
Let me know what you think and if you have any other questions.
Thanks again for the inquiry,