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Discussion Starter · #1 ·
So, I just bought a 4805 and have some concerns.


Right now I have the projector on sorta a high bookshelf with it slanted down so the image will appear in the correct location. I started with the projector about 18 ft from the wall I'm projecting to. I don't have a screen yet.


Now for some questions.


1. I read about people having very wide screens, but from using the projector calculators it seems that the maximum distance from the wall recommended is about 15'. My room is about 20' deep. If I go for a large screen am I losing a lot?


2. The infocus calculator and the projector central calculator don't seem to give the same numbers. Does the projector central calculator only take into consideration a 1.0 zoom factor for the 4805 rather than the 1.2x?


3. When I watch movies on this my contacts seem to give me fits--they seem to dry out quickly and I can see rainbows. The rest of my famility doesn't seem to see the rainbows or be bothered by the image, though. This problem concerns me the most. What are other's experiences?


4. Is it worth the expense of having an installer come out and put in a ceiling mount and run an electrical outlet to my projector? I have huge a/c ducts upstairs and can't really get over the room to drop cables myself. I don't know how the installers will be able to do this.


5. Is it better to run long speaker wire to the speakers with equipment near the projector or to run long video cables? With a 20' deep room I'd see the need for at least 30' of cable...should I run a dvi cable or hdmi? I'd rather run video cable..I've always believed audio cable runs should be as short as possible.


If you've made it through this many questions...then thank you very much! Getting the projector was the easy part...integrating it seems to be the biggest challenge.


I'm thinking I'll make my own screen with blackout material unless I come across a good deal on a screen.


Gowry
 

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1. The farther you go back, the less bright the screen is. The 4805 is a pretty bright projector. Movie standard lamp brightness is 12 foot lamberts. We want the 4805 to achieve a lamp brightness of around this. You also need to take into account if your lamp dims. I would guess you want to have your lamp brightness around 10-16 foot lamberts ideally. I am projecting a 92" diagonal image right now, which is around 26 ftl. I can cut that down to 13ftl by applying a ND2 filter that will cut the brightness in half. Now when my lamp gets to its half life and dim, I can take the filter off, and it's like having a new bulb. Many 4805 follow this idea which is why many recommend a throw of around 15ft.


2. I'd follow the Infocus calculator, it's from infocus afterall.


3. Some people get eye strain due to the brightness of the 4805. Applying the ND2 filter (Hoya HMC 62mm filter) will help with the eyestrain, reduce rainbows, and reduce screen door effect.


4. If you get a quote from a professional installer, I think you won't want to hire one. :)


5. As long as you have quality cables, either way shouldn't be a problem. I think it would be better to run audio as video cables can get expensive.
 

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Quote:
Originally Posted by Ja Phule
I am projecting a 92" diagonal image right now, which is around 26 ftl.
How did you calculate 26ftl? Do you have a high-gain screen? According to the Infocus Excel worksheet, a 92" screen has 14 ftl at 350 lumens (low lamp) on a 1.0 gain screen.


In order to achieve 24ftl on a 92" screen (according to the spreadsheet), you'll need to have a 1.9 gain screen. Please correct me if I am wrong.
 

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SuperGoop


600 lumens new is indeed what it measures for low lamp. Trust Infocus on this one - their lumens ratings are for the default setup - which is film gamma at 6500K and 10% white peaking.


Many satisfied SP4805 thread customers that used a 1.1. High Contrast CinemaVision thought it was initially too bright even - and used a ND2. You will not want to use a 1.9 gain screen as it will be way too bright! 350 lumens is not at all what it measures.
 

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Quote:
Originally Posted by krasmuzik
SuperGoop


600 lumens new is indeed what it measures for low lamp. Trust Infocus on this one - their lumens ratings are for the default setup - which is film gamma at 6500K and 10% white peaking.


Many satisfied SP4805 thread customers that used a 1.1. High Contrast CinemaVision thought it was initially too bright even - and used a ND2. You will not want to use a 1.9 gain screen as it will be way too bright! 350 lumens is not at all what it measures.
I got the 350 lumens on low lamp from www.ProjectorCentral.com 's review:

"In low mode the real lumen output for video content was about 350 lumens, and in high lamp mode it was 450 lumens."


When you say "trust Infocus on this one", where did Infocus say this? Is there some data to support this claim? I am talking about a properly calibrated lumen (not the max).


Did anyone confirm that it is indeed 600 lumens (when properly calibrated)? ProjectorCentral says only 350 lumens on low lamp. Who is correct? Thanks.
 

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That's the problem with ProjectorCentral reviews, we don't know where their numbers are coming from. I usually use the ~600 lumen number that kras himself measured months ago in his x1/4800/4805/H30/7205 comparison. Some people report getting as much as 650 lumens in low power mode with the 4805.


Link:
http://www.avsforum.com/avs-vb/showt...68#post4096268

(I always have a hard time finding this link)
 

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Infocus says it in the manual on the web site 750 lumens is high power, 600 lumens is low power.


You can trust me and be in the right light - or trust PJC and be too bright. Your choice. BTW PJC seems to think that the SP7210 is only marginally brighter than the SP4805. Maybe you should go see a SP7210 sometime so you can decide for yourself if PJC is right or wrong!
 

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Quote:
Originally Posted by SuperGoop
I got the 350 lumens on low lamp from www.ProjectorCentral.com 's review:

"In low mode the real lumen output for video content was about 350 lumens, and in high lamp mode it was 450 lumens."


When you say "trust Infocus on this one", where did Infocus say this? Is there some data to support this claim? I am talking about a properly calibrated lumen (not the max).


Did anyone confirm that it is indeed 600 lumens (when properly calibrated)? ProjectorCentral says only 350 lumens on low lamp. Who is correct? Thanks.
One thing is for certain with the 4805. A 1.9 gain screen would be WAY too much. I use a 1.1 HCCV Da-lite screen, and it's damn bright.
 

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Quote:
Originally Posted by SuperGoop
I got the 350 lumens on low lamp from www.ProjectorCentral.com 's review:

"In low mode the real lumen output for video content was about 350 lumens, and in high lamp mode it was 450 lumens."


When you say "trust Infocus on this one", where did Infocus say this? Is there some data to support this claim? I am talking about a properly calibrated lumen (not the max).


Did anyone confirm that it is indeed 600 lumens (when properly calibrated)? ProjectorCentral says only 350 lumens on low lamp. Who is correct? Thanks.
350 lumen! Good Grief! This remind me why I stop reading Projector Central Reviews...


I used Kras Spreadsheet and 600 lumens over an old 92inches Diag 1.5 Gain Da-lite Screen and it is too brite. I am changing the screen for an HCCV with a 1.1 gain.


Benoit
 

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Dont trust Projector Central! Kras really knows what he is talking about. If what PC is saying was true then my image will be too dim with 350 lumens and a 9' wide screen but the reality is far from that.


Kras, I see that you posted 10% white peaking as the default from Infocus. I have tried that feature and it some times make things look nice but I guess isnt correct to use it, is it?

Regards


Regards
 

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Discussion Starter · #11 ·
Thank you all for your replies. This helps a lot.


When I looked back at PJ Central page the calculator is different now...maybe I accidentally selected the wrong projector before.


I'm thinking I'll run a screen somewhere between 8' and 9' wide. Depends on if I think I'll want to add more seating closer to the screen later. The only seating I have now is a couch that will sit about 16' back.


I'll check into an ND filter, too. It's nice to know that the standard is 12ftL. Is there an easy way for me to check the screens brightness? Maybe some kind of SLR camera test?..actually my brother might have a light meter he uses with his camera.


I also think I'll buy a long set of component cables...if I have it installed by someone else, I'll also look into getting a long HDMI cable as well--just so that I wont' have to run cables again in the future.
 

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It seems that most everyone talks about using a Hoya ND2 filter without necessarily trying to achieve the 12ftlbrt benchmark...


Here is the meat of my question:


Does anybody know how the various filter intensities work to reduce transmitted light?


I have a 67" wide 16x9 screen. The Infocus calculator says that this results in 37.6ftlbrt

with my current 1.1 gain screen. It seems that what I would actually want is perhaps a

ND filter that would cut this to 1/3 output for a fresh lamp and maybe to 1/2 or 2/3 for an

experienced (old) lamp.


I found the following article which explains roughly the difference between Hoya's scale and others but as it is photography related it uses units like f-stop (aperture) rather than

lumens or percentage of light output reduced...

http://www.cs.mtu.edu/~shene/DigiCam...filter-ND.html


Does anyone have a simple explanation of the various filter levels?


Take care,
 

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Quote:
Originally Posted by Gowry
Now for some questions.


1. I read about people having very wide screens, but from using the projector calculators it seems that the maximum distance from the wall recommended is about 15'. My room is about 20' deep. If I go for a large screen am I losing a lot?


2. The infocus calculator and the projector central calculator don't seem to give the same numbers. Does the projector central calculator only take into consideration a 1.0 zoom factor for the 4805 rather than the 1.2x?


3. When I watch movies on this my contacts seem to give me fits--they seem to dry out quickly and I can see rainbows. The rest of my famility doesn't seem to see the rainbows or be bothered by the image, though. This problem concerns me the most. What are other's experiences?


4. Is it worth the expense of having an installer come out and put in a ceiling mount and run an electrical outlet to my projector? I have huge a/c ducts upstairs and can't really get over the room to drop cables myself. I don't know how the installers will be able to do this.


5. Is it better to run long speaker wire to the speakers with equipment near the projector or to run long video cables? With a 20' deep room I'd see the need for at least 30' of cable...should I run a dvi cable or hdmi? I'd rather run video cable..I've always believed audio cable runs should be as short as possible.
1. I would go with a larger screen size. This will also make the picture less bright. I would not bother with filters.


2. I think the projector central calculator agrees with the Infocus one.


3. I would give this a few weeks. Most likely, the "rainbows" will subside. I have similar problems with my contacts, for whatever reason. I believe it's the contrast from the dark room to the bright screen, but I like bright.


4. A pro will fish the wires through. It may not be as impossible as it seems. Check a home wiring book at the bookstore for illustrations, you may be able to do this yourself. At the most, I would hire an electrician to wire the electrical box.


5. Run long speaker cable.
 

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Quote:
Originally Posted by mdl
1. I would go with a larger screen size. This will also make the picture less bright. I would not bother with filters.
Go big but stay 2x the width of the screen back. If you get closer you run the risk of being distracted by pixel structure/screen door effect.
 
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