30’ throw with an Epson 5040UB?

crimsonblue said:

I’m considering the projector placement right now, and it dawned on me that I have a 24” rear soffit where I could put a projector. Easy connections to the rack, and completely out of sight, minus the hole for the lens to pop through.

An Epson 5040UB can throw 30 feet to a 150” screen. What are the pros and cons of having it back that far?

Brightness may be slightly less (image would be telephoto light cannon vs a wide angle, but supposedly the contrast would be better.

Anyone else do a long-throw projector and/or have thoughts?

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Light is subject to the inverse-square law. Simplistically, if you double the distance from the light source, you will have 1/4 the intensity. If you triple the distance from the source you will have 1/9 the intensity, etc. You also have to understand that while doubling the distance results in 1/4 the intensity, the light is also spread out over 4 times the area and triple the distance will result in 9 times the area, etc. as well.

In your case, you're proposing to use the same area of illumination or a fixed area, that is a 150" diagonal 16:9 aspect screen. Using that fixed area within the throw distance zoom range of the 5040 for that fixed area should give you ~ the same brightness within that throw range of ~14'-30'. Any drop in brightness will be associated with the lens' speed and construction and not so much the inverse-square law as the lens is able to concentrate the light flux on the same size area using the telephoto aspect of its design. In other words, you're not going to see a very noticeable difference in brightness in your situation.

No doubt people posting will take exception sighting the lumen drop as reported in Projector Reviews review of the 5040ub and different throw/zoom positions. What's not taken into account is that Projector Reviews reports different throw/zoom positions with different image sizes. Any brightness drop suggested sighting this review as a reference is inaccurate and an apples and oranges comparison as you're proposing changing the throw for a fixed size area vs. brightness drop from the review using different size areas. This of course brings you back to the inverse-square law and will account for the difference in brightness relative to the area illuminated in Projector Reviews review.

IMHO the Epson 5040ub is perfect for your application of mounting at 24' and stretching the throw to 30' if you must. Keep in mind that the brightness or foot-lambert value (what your eye sees) can be mitigated by increasing the screens gain. Increasing the gain from a 1.0 screen to a 1.3 gain screen can get you an easy 5-8 fL increase with the same throw from the same projector and settings.

Very interesting -- and differing -- perspectives!

This adds some visuals to my setup. There is a bulkhead all around, extending 24 inches in the back, 36" on the sides, and 48" in the front (to hide the speakers behind the screen).

35 feet total
-3 feet in front (bulkhead will overhang screen by 12" for lights"
-2 feet in the back for projector mounting in box
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30 feet of throw

b curry said:

...Projector Reviews reports different throw/zoom positions with different image sizes.

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No, they do not.

When you change the zoom on a lens, you change the aperture of the lens, with longer throw reducing the aperture and reducing the light output that the lens is capable of. This is photography 101. To get the same amount of light through a lens that is further away from something you need a much larger lens. This is why you see professional photographers with absolutely huge telephoto lenses. It's not to get the zoom, it's to capture the light into the lens.

With reviews I've done, I move the projector closer and further and keep image size the same (110" diagonal) and my light meter in the same position. If they simply adjusted the zoom without moving the projector and keeping the same image size that would indicate that they have no idea how lenses actually work or how to do their job.

Projector Central, by example, specifically measured a 33% falloff in light output for the 5040UB from closest to furthest.

So, with a 150" diagonal, which is 66.4 square feet, and a desire for at least 15 lumens per square foot, you would need right around 1,000 lumens minimum. This won't deliver solid 3D, and it will lack with some punch, but will work.

Since this is what really matters, then 1,500 measured lumens will be an absolute minimum (with 33% light loss) and that's something that the 5040 can't really do in it's absolute best mode, but can do bright cinema, in low-lamp mode, and get 1,800 lumens (closest) with about 1,200 lumens at 30' or so. That should be plenty solid for viewing.

But, have no doubt that there will be some light falloff.

The obvious way to get around this is to get a screen with 1.3 to 1.4 of gain and get that light right back! A minimal gain screen does a great job of adding punch, versatility, and flexibility to any installation that may need it. This one especially.

AV_Integrated said:

No, they do not.

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Well then I would refer to section 8. EPSON HC5040UB, PC6040UB HOME THEATER PROJECTOR REVIEW PERFORMANCE - LAMP MODES, ZOOM EFFECT

Please explain why they list 3 zoom position lumen values each with a different image height.

https://www.projectorreviews.com/ep...or-review-performance/#lamp-modes-zoom-effect

AV_Integrated said:

When you change the zoom on a lens, you change the aperture of the lens, with longer throw reducing the aperture and reducing the light output that the lens is capable of. This is photography 101. To get the same amount of light through a lens that is further away from something you need a much larger lens. This is why you see professional photographers with absolutely huge telephoto lenses. It's not to get the zoom, it's to capture the light into the lens.

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Correct. After looking at the spec's of the 5040ub, it has an f stop range, with out doing the math, of slightly more than one full stop. As I said in multiple posts, it will depend on lens speed. All lens/projectors are not equal as I'm sure you're aware. But the difference between mounting a 5040ub at 24' vs. 30' is de minimis. And will stand buy the fact that one would have to compare two 5040ub's side by side with the extreme's of the zoom limits and the projectors adjustments to see the difference and that an increase in screen gain from 1.0 to 1.3 will offset much of the difference.

AV_Integrated said:

With reviews I've done, I move the projector closer and further and keep image size the same (110" diagonal) and my light meter in the same position. If they simply adjusted the zoom without moving the projector and keeping the same image size that would indicate that they have no idea how lenses actually work or how to do their job.

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Who could have guessed?

AV_Integrated said:

Projector Central, by example, specifically measured a 33% falloff in light output for the 5040UB from closest to furthest.

So, with a 150" diagonal, which is 66.4 square feet, and a desire for at least 15 lumens per square foot, you would need right around 1,000 lumens minimum. This won't deliver solid 3D, and it will lack with some punch, but will work.

Since this is what really matters, then 1,500 measured lumens will be an absolute minimum (with 33% light loss) and that's something that the 5040 can't really do in it's absolute best mode, but can do bright cinema, in low-lamp mode, and get 1,800 lumens (closest) with about 1,200 lumens at 30' or so. That should be plenty solid for viewing.

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And Projector Central also states that the 5040ub can deliver 41% over spec and that Bright Cinema mode in high lamp comes in at the ~ advertised lumen value. My experience with the newer Epson's shows very little difference in Bright Cinema vs. Cinema for practical viewing. Measurement and calibration, yes, but for practical use, not so much.

https://www.projectorcentral.com/epson-5040ub-review.htm?page=Performance

AV_Integrated said:

But, have no doubt that there will be some light falloff.

The obvious way to get around this is to get a screen with 1.3 to 1.4 of gain and get that light right back! A minimal gain screen does a great job of adding punch, versatility, and flexibility to any installation that may need it. This one especially.

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See my first post in this thread.


So if one were to use Bright Cinema mode, recommended in the Projector Central review BTW, at 2400 lumens and discount the value by 30% for the maximum throw with a 150" screen you would be left with 1680 lumens. 1680 lumens would yield 25 fL on a 1.0 gain 150" screen and 33 fL on a 1.3 gain screen of the same size.

https://www.projectorcentral.com/eps...ge=Performance


SMPTE 196M defines the luminance target as 16ftL open gate or without a film in the projector, which typically equates to ~14ftL with a film. So using the 16 fL open gate number, the 5040ub would yield ~60% more luminance than required by SMPTE 196M on a 1.0 gain, 16:9, 150" screen and an ~110% luminance over SMPTE 196M using a screen of the same size with an increased gain of 1.3.

Is there something wrong with that? I don't know, but it seems to me there is some room for some lamp ageing in there too.

b curry said:

Well then I would refer to section 8. EPSON HC5040UB, PC6040UB HOME THEATER PROJECTOR REVIEW PERFORMANCE - LAMP MODES, ZOOM EFFECT

Please explain why they list 3 zoom position lumen values each with a different image height.

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You know, I'm not sure, but the reality is that I suppose that is another way to do things. I never thought about doing my measurements that way, but by the numbers they are giving, they did it exactly right...

With a image 66" tall and a total light output of 2137 lumens, then the meter would read about 39.51 lumens/foot over a 53.625 square foot screen area. (likely measured in nits and converted).
With a image 48.75" tall and a total light output of 1850 lumens, then the meter would read about 61.57 lumens/foot over a 29.94 square foot screen area.
With a image 31.75" tall and a total light output of 1463 lumens, then the meter would read about 115.47 lumens/foot over a 12.67 square foot screen area.

I wouldn't do my measurements that way, but as long as you plug in the math for the screen size you are working with, the math still is the same. So, with my 110" diagonal, I have a 35.625 square foot screen, so whatever my lumen measurement is, I multiply it by 35.625 to get the total lumen output of the projector. That certainly seems easier than fully calculating size every time, but if they have a room with limited placement flexibility, which is very likely in a good theater space, then they probably don't have the option of moving the projector 20+ feet out. So, they just changed the size and did measurements that way. It may be a lot easier to do things that way.

In reality, with the rise in the measured lumens that the meter would show with a smaller screen size, if they had done the math wrong, they would show much higher brightness. Instead, their math indicates very similar light output falloff that Projector Central also claimed in their review.

Can we agree that the math on this looks accurate and both sites are performing valid tests of light falloff related to zoom of the lens?

b curry said:

So if one were to use Bright Cinema mode, recommended in the Projector Central review BTW, at 2400 lumens and discount the value by 30% for the maximum throw with a 150" screen you would be left with 1680 lumens. 1680 lumens would yield 25 fL on a 1.0 gain 150" screen and 33 fL on a 1.3 gain screen of the same size.

https://www.projectorcentral.com/eps...ge=Performance


SMPTE 196M defines the luminance target as 16ftL open gate or without a film in the projector, which typically equates to ~14ftL with a film. So using the 16 fL open gate number, the 5040ub would yield ~60% more luminance than required by SMPTE 196M on a 1.0 gain, 16:9, 150" screen and an ~110% luminance over SMPTE 196M using a screen of the same size with an increased gain of 1.3.

Is there something wrong with that? I don't know, but it seems to me there is some room for some lamp ageing in there too.

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I fully believe that the projector will look excellent at that distance. I like playing with the math, so hopefully you didn't read anything that was going after you in my post. Just working the numbers. I'm sure I read both reviews at some point, but it would have been a solid year and I'm sure the numbers didn't register with me.

25 lumens is plenty of light on any screen for non-3D viewing. It may be a bit tough for 3D viewing. They can certainly turn some lights on as well as long as they aren't falling right on the screen or too close to the screen. Projectors certainly do a very good job with their increased brightness in recent years, and Epson seems to be really leading the pack with their LCD models and superb color brightness.