Confused on throw distance? - AVS Forum
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post #1 of 17 Old 03-31-2009, 10:37 AM - Thread Starter
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I am thinking about buying a Marantz VP-15S1. Based on this chart http://us.marantz.com/Throw_Distance...P-15S1_MAI.pdf I think I should be okay. My screen will be 54 inches high by 129 inches wide 2.40:1 AR, so my 16x9 image will be 110 inches diagonal. My screen width will be 96 inches(16x9) and I want a 2.0 throw to use with a panamorph lense. That will give me a projector to screen distance of 16 feet. Am I calculating this correct? I have seen on the Marantz website this number, Throw Distance 100" , 127 1/2" - 185 1/4". What does this mean?
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post #2 of 17 Old 04-02-2009, 06:05 AM
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The numbers mean the throw ratio range for the standard lens is below the 2.00 ratio needed for your application. I believe Marantz offers a separate long throw lens option, for a little more money, but which will get you where you need to be.

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post #3 of 17 Old 04-02-2009, 06:57 AM
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Come on Jedi. The Marantz chart is based on screen diagonal not width. His screen is a 110 inch diagonal. The chart gives minimum throw for a 110 inch diagonal at 139.8 inches and maximum throw at 203.6 inches. He wants a throw of 16 feet or 192 inches. This is the distance horizontally from lens to screen. So he doesn`t need a different lens than the standard. The throw range for the standard lens is 1.456 times the screen WIDTH to 2.12 times the screen WIDTH.

Jay. You will be fine with a 16ft throw for your 16 x 9 width of 96 inches.

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post #4 of 17 Old 04-02-2009, 10:29 AM
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...I stand corrected, did not notice Marantz bases charts using diagonal. Regarding application, the scope image will require around 500-600 actual lumens unless a high gain screen is being deployed. That's a lot to ask from the VP-15, and getting there will need iris cranked wide open. Need to make sure screen gain is adequate, or otherwise, make sure op will be happy with resulting contrast with iris all the way open.

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post #5 of 17 Old 04-02-2009, 01:34 PM - Thread Starter
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Thanks for the replies. I used Jason Turks numbers for lumens on iris 1 he got 358, which would put me around 13 ft lamberts 1.3 gain screen. Now I realize this is a brand new bulb. I might be able to squeeze out 15 ft lamberts or so on iris 2. I don't think I want to use iris 3 for all my viewing, maybe I should think of a different projector, but I really like the image the Marantz throws. Also when I calculate ft lamberts, do I use the 16x9 image size even though I am using a 2.35:1 AR screen. When I put the lens in front of the projector for 2.35:1 movies, I am increasing brightness correct? Sorry if this has been discussed before. Maybe I should consider a JVC RS-20. I know these are different technologies, but would the JVC give me a bright enough picture for this size screen, would I be disappointed with the picture compared to the Marantz?
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post #6 of 17 Old 04-02-2009, 01:51 PM
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...the anamorphic stretch will spread the projected lumens out over a larger area, thereby reducing the brightness level compared to the 16:9 configuration. At 358 lumens onto a 1.3 gain screen in scope mode you will be getting around 9-10 ft-L with a new bulb. This level may be fine if you have good light control, otherwise it may be too dim. You can of course crank the lumens up at the expense of contrast ratio by opening the iris. You would benefit greatly by auditioning this projector zoomed out on a comparable screen material and comparable room lighting levels to give you roughly this level of image brightness to see if you will be happy with the results. Also play with the iris see which settings give you the best results.

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post #7 of 17 Old 04-02-2009, 01:57 PM
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Maximum light output would be with the full chip being used. No bars. You take the light out in lumens multiply by the screen gain of 1.3 and divide by the screen square footage. That gives you foot lamberts. So watching a fully lit 16 x9 screen (uses the full chip, no bars, like HD TV) you will get a number. At 2.40 using the full chip by electronically stretching the image vertically to fill the entire chip (its already filled horizontally) you increase the image optically to fill the 2.4 screen. The lumens remains the same, the screen gain remains the same, but the sq footage of the screen increases so the foot lamberts will go down. Somelike like by 1/3. Your eyes don't record brightness linearly so it won't like 1/3 down but it will decrease in brightness by about 1.3.

BTW Why aren't you using a 2.35 aspect screen. Most wide screen movies are less than 2.4 (2.38 or so) and you will have some unlit screen. Using a 2.35 would be much better. For movies above 2.35 but below 2.4 you will have just a smidge of overscan.

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post #8 of 17 Old 04-02-2009, 02:00 PM
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Jedi and I posted simultaneously. Sorry for the repeat.

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post #9 of 17 Old 04-02-2009, 03:03 PM - Thread Starter
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I have read the thread about 2.40:1 vs. 2.35:1 and still can't really decide which AR to use. Do you have any comments about the JVC. I will have the chance to look at the JVC in a couple of weeks on a 12ft wide screen. Inccidentally the company that I will be viewing the JVC at, recommended the 2.40:1 screen. I really don't want to decrease the size of my screen, but I also don't want a dim picture.
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post #10 of 17 Old 04-02-2009, 03:56 PM
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No offense but many companies are not truly expert. There is little physical size difference between a 54 inch tall 2.35 and 2.4. You are widening things only 2.7 inches or 1.35 on each side. The problem is that you would like the image to be black masked by the screen frame or variable screen masking. Lets take a 16x9 image on either a 2.35 or 2.4. Unless you add drpo down masking on each side, you will see light screen material on either side. No black bars. So adding masking to mask a 16 x 9 is nice if affordable. If you have a 2.35, most every wide screen image will completely fill the screen letting the screen frame mask the side edges. If your screen aspect goes to 2.4, many wide screen movies won't completel;y fill the screen. The side black edges of the screen won't make the edges sharp because there will be a small amount of screen material unlit.

A 2.4 screen is ideal if you have variable screen masking that moves horizontally from the sides allowing you to in essence make that 2.4 screen 2.38 or 2.35 to remove any unlit screen. It can move all the way down to 16 x 9. Everything will be perfectly masked. BUT SUCH SCREENS ARE VERY EXPENSIVE. When one has just up down masking to make a wide screen 16 x9, the right way to go is to get a 2.35 screen and just overscan a bit, filling the entire screen, edge to edge, You lose a little bit on the edge but your masking and its effect on image quality will be the best.

Your eyes in a dark room adapt to the brightness or lack of it. In CRT FP days, we lived with low foot lamberts. Things were fine. We quibble about what is ideal now. 12 ft lamberts or so. 10 ft lamberts isn't bad. It doesn't look 17% less bright, just a tad dimmer to your eyes.

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post #11 of 17 Old 04-02-2009, 04:14 PM - Thread Starter
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Thanks Mark,
I probably will have masking, maybe the new Carada CIH system. I should probably post this in another thread but, should I consider the Planar 8150? It is bright enough and has better contrast than the Marantz. Does the new improved Planar 8150 have a variable iris or a fixed one?
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post #12 of 17 Old 04-02-2009, 07:55 PM
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Quote:
Originally Posted by Jay5298 View Post

Thanks Mark,
I probably will have masking, maybe the new Carada CIH system. I should probably post this in another thread but, should I consider the Planar 8150? It is bright enough and has better contrast than the Marantz. Does the new improved Planar 8150 have a variable iris or a fixed one?

The 8150 and the 8130 both use DynamicBlack, which is a type of variable iris in the optical system.

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post #13 of 17 Old 04-02-2009, 08:56 PM - Thread Starter
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Quote:
[The 8150 and the 8130 both use DynamicBlack, which is a type of variable iris in the optical system.

Can the projector be set to different iris modes or settings like the Marantz so you can have increased or decreased brightness, or is it always on a certain setting? I assume it has economy lamp and high lamp modes.
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post #14 of 17 Old 04-03-2009, 04:58 AM
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Jay, The Marantz does not use a dynamic iris, The Planars do. Everything in this thread can be found all over various AVS forums. It really would be best to PM somebody you trust here who knows a lot about the various model projectors you are considering and constant height set ups yada yada to answer your basic questions, either by pm, phone, or other contact. You seem very confused and there is no shame in not understanding a lot of things many of us take for granted. For example, DI machines. Some love them, some hate them. This is not the thread to discuss them in detail.

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post #15 of 17 Old 04-03-2009, 07:13 AM
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Quote:
Originally Posted by Jay5298 View Post

Can the projector be set to different iris modes or settings like the Marantz so you can have increased or decreased brightness, or is it always on a certain setting? I assume it has economy lamp and high lamp modes.

Right now, the iris is either in dynamic mode (DynamicBlack) or off. You get an 3-4x increase in contrast with DB on (the native FOFO CR is ~5000:1, so with DB on you get ~15-20K). The projector defaults in eco lamp mode (~800 lumens) and both the standard and short throw lens have a 72mm filter thread if you want to add an ND filter. You can also set ISF Day and ISF Night modes where DB can be programmed on or off.

Remember that the benefit of DB is that you get the contrast AND the brightness unlike a static iris where you get contrast OR brightness.

You can PM me if you are interested in a demo.

Thanks,

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post #16 of 17 Old 04-03-2009, 09:17 AM
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Quote:
Originally Posted by Jay5298 View Post

Thanks for the replies. I used Jason Turks numbers for lumens on iris 1 he got 358, which would put me around 13 ft lamberts 1.3 gain screen. Now I realize this is a brand new bulb. I might be able to squeeze out 15 ft lamberts or so on iris 2. I don't think I want to use iris 3 for all my viewing, maybe I should think of a different projector, but I really like the image the Marantz throws. Also when I calculate ft lamberts, do I use the 16x9 image size even though I am using a 2.35:1 AR screen. When I put the lens in front of the projector for 2.35:1 movies, I am increasing brightness correct? Sorry if this has been discussed before. Maybe I should consider a JVC RS-20. I know these are different technologies, but would the JVC give me a bright enough picture for this size screen, would I be disappointed with the picture compared to the Marantz?

Remember this is with a brand new lamp. After hours are put on it, it will dim. 13 is pushing it to start with but give you little to no wiggle room. You'd probably find running Iris 2 is a better bet (at the sacrifice of your contrast abilities).
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post #17 of 17 Old 04-03-2009, 09:18 AM
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Also your math in post #1 is okay IF you are using an HE lens...Panamorph does also make VC in which case it would be different.
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