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Projector Brightness

Discussion in 'Multimedia, Projection, and Show Control' started by LPdan, Mar 22, 2018.

  1. LPdan

    LPdan Member

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    Hello,
    I just purchased a Panasonic short throw projector with 5500 lumen output. Intent is to hang from pipes around 25' from cyc and project backgrounds. I just received it and only had a matte dark gray wall to test on, but the brightness seemed nowhere near enough to fight ambient stage light. However, it seems like many people are successfully using projectors with even lower outputs. Am I being fooled by the dark gray wall? Is this really enough power for the application in general?
     
  2. dbaxter

    dbaxter Well-Known Member Premium Member

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    The gray wall is not doing you any favors, but expect to adjust your front lighting whenever you have a projection running. Your lumen output will show on a semidark stage, but don't expect it to overcome, say, those two Source 4's you have showing a soft focus breakup on the cyc. Adjust your blocking to be 10' or more in front of the cyc to allow for more down light and less back light. To me, a short throw is under 20', so it's not clear what your mounting configuration is. Keep the inverse square law in mind when you decide your final mounting point. You may have to compromise how close to the cyc you can go with the keystone adjustment range on your projector. Just some 'techie' thoughts.

    On the good side, we've used a 6000 lumen projector mounted about 30' from the back wall with good results. Doesn't blow you away, but with careful adjustment of the other lighting to avoid hitting the wall, is clear enough.
     
    RonHebbard likes this.
  3. LPdan

    LPdan Member

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    Thanks for this advice. To clarify the mounting, I plan to hang from a fly bar at very front of stage, in this case it's a throw of around 25 ft. In my straight on test (not angled from above), at 25' I got good image 21' wide x 11' tall. The projector throw ratio is 1.08-1.76 : 1.
    So as long as I don't aim any lights directly on cyc, this could work? Any idea how much of an impact stepping up to 7000 lumens would have? I know the effect on price, but it it made a huge difference I would consider it.
     
  4. mikefellh

    mikefellh Active Member

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    Make sure your projector is set to full power, and not ECON mode.
     
  5. TNasty

    TNasty Active Member

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    We did something like this a couple years ago (except with the back of house mounted projector... it sure was interesting adjusting it so it didn't visibly project on actors.

    As people above have mentioned, don't expect it to look like a massive flat screen TV, there's just simply not enough brightness in most projectors to overcome stage lights. Also that setting it to full power instead of "normal" or "eco" can help.

    When I did this, one of the tricks we used was to aim our cyc lights a bit more downstage instead of the cyc (this worked relatively well for us with our Altman R40's, your mileage may vary). Objects and structures on set certainly had the hue we wanted, and there was enough light spilling onto the cyc that it didn't look like a massive white curtain, but not enough to stop the projector from looking good.

    Also, depending on your projector, you may be able to set the fans to "high altitude" or "performance" or something (the NEC's I wanted to set up for a triple wide had the option). If there's already enough ambient noise, or your theatre is big enough, there's no big deal with ramping the fans up. With all the extra heat up around the battens, it may just be better if you keep the fans at a steady speed instead of possibly hearing something randomly "roar" throughout the show.

    I don't know how big of a difference you'd get in upping the lumens. Partly because I haven't looked at a side-by-side comparison, but mainly because I've already got enough math to worry about right now.

    On a side note, how do you plan to hang these? We custom built brackets for our project, and ran safety cables through the handles on the projectors, but I'm interested to hear the routes that other people go with hanging projectors from battens.
     
  6. josh88

    josh88 Remarkably Tired. Premium Member Fight Leukemia

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    Spill light will kill you, but 5500 lumens is probably the biggest struggle, thats not a ton of output, super easy to wash that out. Even 10k projectors can get washed out if you aren't careful about where your light is.
     
    RonHebbard likes this.
  7. soundofsparks

    soundofsparks Active Member

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    When you're talking about competing with lights, remember that just one HPL lamp in a Source Four can output 16,000 lumens. So, unless you're dealing with 20k+ projectors, you're going to have to keep light off the image.
     
  8. ruinexplorer

    ruinexplorer Minion CB Mods Premium Member Fight Leukemia

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    Here are a bunch of things to think about.

    Projector brightness is only part of the projection puzzle. You have helped us a bit by telling us how large an image that you are hoping to achieve (as stated with the inverse square law, the smaller your image from this size, the brighter your image will be, so that might be an option for you).

    We can assume that you have a new projector with a new lamp. This will be the brightest that you will ever get. So, if you can't make it work now, as the lamp/projector ages, you will get poorer results and be less happy. Lamps will have a noticeable brightness drop as they age. Usually, you can get close to full brightness for the first 200 hours or so. After that, the lumen hill starts getting steep and you will lose brightness faster the older the lamp. For the purposes of my show, I replace the lamp at 2/3rds its stated life as it gets too dim for my purpose.

    Apparent brightness from a projector (not measured) will have a few variables. As humans are most sensitive to contrast (bright to dark ratio), how bright your projector is will only be a part of this. Most projector manufacturers will state the highest contrast achievable by the projector, which isn't really helpful. For one, this is telling you the difference between full white and full black (which can be helpful to know how bright "video black" is). You need to know what the ANSI contrast is (as measured by a checkerboard of 16 white and black squares). This is helpful in determining what the contrast of your content will be. Tiny amounts of ambient light will greatly impact this ratio. In addition, the surface that you are projecting on will add into the equation. With a traditional projection screen, we know what the gain (reflectance variable) will be. Without knowing, we generally derate the surface to a gain of 0.5 (scattering the light more or potentially absorbing it) which usually works for an off-white cyc. The apparent brightness can be affected by the type of optics used to generate the image. A 3-panel LCD will appear brighter than a single-chip DLP (which will have roughly the same price point) when you are showing anything besides a full white screen. The lamp technology can play into this as well, but you probably just have the standard lamp based projector, so this will be less noticeable. Since a 3-chip DLP will generally have a better ANSI contrast ratio than the same brightness 3-panel LCD, the DLP projector may seem brighter as well (this can depend on the surface and ambient light). Finally, the content that you choose will make a difference in how bright a projector seems. If you have brighter colors covering a greater amount of your image (and have good contrast), then your image will be more acceptable.

    If you intend to rig the projector to one of your battens, please use a manufactured assembly, preferably by the manufacturer, but there are a number of secondary manufacturers (Chief, Premier Mounts, etc.) that also make quality equipment. These will either have pre-determined mounting points which match to the bottom of the projector or will be adjustable to fit a variety of projectors. The biggest challenge to rigging to a batten is that your image may move as the batten will likely swing as you move other scenery (including soft goods) or as air currents change.
     
    RonHebbard likes this.
  9. Chris Stolz

    Chris Stolz Member

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    I just spent a few days teching a show with a 5500, but as soon as the lighting started to kick in my projections were toast. Try as he might, the LD just couldn't prevent ambient light from hitting the screen without sacrificing the visibility of the actors.

    We ended up renting a 14K (Barco RLM-W14) which wasn't perfect, but did the job reasonably well. You can find pictures in this post.
     

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