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Old January 20th, 2006, 11:07 PM   #1
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Lighting presenters and not projection screen

A search on this forum for 'powerpoint' took me to a discussion of lighting for a single person speaking at a podium along with a Powerpoint presentation.

One suggestion was to use fluorescent lighting close to the speaker.

I do intend a DIY project just because I want to try fluorescent lighting, but I'm not convinced this would be the best way to go for the particular situation where the presenters are right next to the video projection screen.

I have two presenters seated in chairs on one side, and two others on the other side, of a video projection screen. Actually, what I call a screen is really a white wall framed by two windows. This is at night.

What would barn doors accomplish for a diffuse gaseous light source other than just reduce intensity? Can I really control the light that might otherwise spill onto the screen?

I have to turn off the fluorescent ceiling lights for the video projection, so I'd be concerned with putting not one but two comparable fixturs on a stand. How is this going to be any different?

I figure would need two lighting units, one for each side. It might be quite a trick to keep them out of the camera shots, since this is a close, intimate arrangement. The chairs are arranged in semi-circles, and there is only a few feet of space between presenters and audience.

I thought that perhaps the video projection itself might provide some fill. Earlier I had been thinking of a pair of fresnels to give me a somewhat diffuse circles of light on each side, tight enough not to spill onto the screen. The issue was where to safely place them in a crowded room. I had also given thought to a low wattage lamp that I could attach to the drop ceiling with a scissors clamp.

There is sufficient room lighting plus light from the video projection to get something of an image, albeit with a good deal of video gain noise. I think getting better exposure is more important than modeling the subjects.

I do have at my disposal two 500W Lowel open faced halogen light w/ barn doors, and a 500/1000 W Lowel soft light (the type where the light faces back bounces off a silver fabric) plus three C-stands.

Any suggestions? I am new to all this.
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Old January 21st, 2006, 08:25 AM   #2
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Hi Chris, and welcome to DVinfo. We do this sort of thing all the time in stage lighting, but the ideal would be to use some sort of focusable instrument and not one with an open face of a fresnel lens since they have a lot of "spill". If you have to use one of those then barndoors can help, but there will still be a lot of flare to deal with.

The ideal would be to use a couple of ellipsoidal reflector spotlights like the ETC Source 4 or Source 4 Junior:

They have internal shutters which can be used to shape the beam and keep it off your screen, and the lens allows you to bring the beam in sharp focus. For an extreme situation you can put a top hat (black metal cylinder) on the unit to eliminate even more spill.

I don't know if your venue provides an existing lighting position, but if not then you could rent a pair of boom stands to mount the lights. Locate them on either side such that you can light the speaker without the beam directly hitting the screen. The ideal would probably be putting them high enough to form a 45 degree angle from above.

All this stuff, along with cables, gel frames, etc. should be relatively inexpensive to rent for a day and available at any theatrical supply rental house.
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Old January 21st, 2006, 01:51 PM   #3
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I am new to lighting also. In fact the thread you are referring to sounds like my original post. Next week I am shooting a simular set-up. Mine is just a single speaker with powerpoint. Based on advice from this site, my budget, set-up time and existing equipment.

For the Key, I plan on using a single 300 watt lowel omni with glass diffuser on a stand 45 degrees off horizontal and about 45 degrees off axis of the presenter. I will use the barn doors to reduce spillage and try to tweak the positioning of the screen to further reduce spillage. Im my case there is a logistical problem in renting lights, so I will use what I have. I see that there is a snoot option for the Omni. Could this be used to further focus the light?

Also using a LCD projector with 3000 or more lumens might help. I am stuck using the Omni but I still have time to adjust the set-up. Does any one has any suggestions for us?
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Old January 21st, 2006, 10:41 PM   #4
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Generally, rear projection tends to show less light splash. The reason is that the screen is transmissive. Much better for video lighting than front screen.

In the case of rentals, larger rear screens are about equal in price to larger front projection screens. Sometimes the AV company includes both front and rear surfaces for "fast-fold" style screens.

You do need room in back of the screen for projection distance...
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Old January 23rd, 2006, 09:43 AM   #5
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When using a soft source, such as a kino-flo type light or a fresnel with diffusion, it often helps to place a large flag 2-5 feet in front of the light, which allows you to define the edge of the light more distinctly than onboard barn doors. If you can use a 36" professional felt flag attached to a C-Stand, but really anything opaque will do. I'm rather partial to using foam core, black on one side, white on the other. I carry some around all the time to make improvised flags. You can even cut them to shape, if needed, and if you have a c-stand with a grip head, you can just clamp the head down. You can also use big spring clips called grip clips, or pony clamps to attach a flag to a light stand. You can even buy these at home depot - they're quite useful:
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Old January 23rd, 2006, 01:14 PM   #6
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Cris, you didn't mention how you plan to cover this event, but if you only have one camera, I would guess you will spend a lot of time on a wide shot that shows the screen and the four participants, or a variation such as the two left speakers and the screen. What I am getting at is what determines your exposure setting, and in this case it is the brightness of the screen. You should test the screen when you do your set-up, and this could be a problem if you have to set-up during daylight hours. Anyway, you need lights that offer you some latitude for exposure, and so I would advise you to forget using the fluorescent lights, unless you have access to higher output versions similar to those used in news sets, and I don't imagine that's possible. The best solution is what Boyd recommends with the Source 4 Jrs, but I have a hunch that's not possible either. So what you are left with is those two 500 watt Lowel lights.

I would suggest you mount them to the ceiling, one on either side of the screen, slightly in front of the speakers. How you mount them to the ceiling is for you and your venue to work out. Safety first. You don't want them falling down on the audience during the presentation. There are liability issues here, so beware.

After you hang the lights in place, to set the proper exposure, get the room as dark as possible, fire up the projector with a representative slide on the screen, and set your exposure. Now place a couple stand-ins in the chairs and get at the first light and focus it on the first two chairs. To "focus" the light, go to the full spot position on the light, and aim the light between the two chairs and tighten it down in place. Next go to full flood position on the light. This will give you the smoothest, most even spread on the two people. Now check the exposure. Hopefully it will be a perfect match between the screen and the people. Wanna bet? If you have too much heat on the speakers, you have a couple choices; you can either use a dimmer on the light, or add a piece of diffusion. (Additionally, if possible you could heat up the projector.) If you need a bit more heat on the speakers, you can try focusing the light from full flood to a bit toward spot. If you need a lot more light on the people, you are screwed, unless you can bring down the projector output. Once you get a balance between your light and the projector, duplicate the set-up on the other side.

I would also suggest you spend the money for a roll of blackwrap, which you can find at and elsewhere. A piece of blackwrap attached to the ceiling tiles will help prevent discoloring the tiles from the lamp heat. This is very important. You can also use additional blackwrap to augment the cheesy barndoors on those lights, to help keep it on the speakers and off other areas.

Wayne Orr, SOC
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Old January 24th, 2006, 10:32 PM   #7
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Thanks Scott,

I just made a Foam Core Flag that will go next to my Omni. It works great and is such a simple solution. Now I can have he presenter in the light and a sharp shadow for the screen.
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Old January 31st, 2006, 09:04 AM   #8
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Lower cost alternative to ellipsoidals?

First, thanks to all who offered suggestions. I am new to this forum, and I was expecting an email notification for replies which never came. Then, I forgot the DVinfo URL. In any case, I am back now, after setting up lighting in another venue, also with video projection, but a different kind of setup.

Ellipsoidal reflectors would seem a good bet. Rear projection is not an option. I am very hesitent in using my 500 W Lowels, but I should have some sort of fill, some how.

For this last shoot, I wanted a back light for the speaker. I decided on a DIY solution using a track light with 50W halogen spots, PAR with 15 deg, beam spread. I used two of the 50W spots for back light, though I did need to use black wrap. I am considering adding some sort of snoot. Also, the particular spots I used have removabler tempered glass UV filters, so I am thinking I might be able to find color correction filter in glass with the same diameter in place of the UV filter.

I am also thinking of using the same slide projector type PAR lamp for at least some of the lighting for the subjects mention in my original post (two pairs of subjects on both side of the video projection).

The venue is a fairly large room in the annex of my church, so permanent track lighting, provided it was on a tight budget, is a possibility. But for now, I need to bring my own lighting in. Rentals are difficult because locally, there are no viable options. That means a 1-1/2 hr trip to Syracuse or Rochester. Still, rentals would be theway to go to try something out if I didn't have a low cost DIY solution also worth trying out.

The room mentioned has low suspended ceiling. Rear projection would not work in this particular configuration. If I have the lights mounted 8' up from the floor up and I wanted them to beam down 45 deg to the subject, that would put them pretty close to the subject, so I am thinking I wouldn't need as much power for a key light and two 50 W lamp, or 100 W, might be sufficient.

I am thinking that by adding improvised snoots to this inexpensive track lighting, and having the lamps close to the subject, I might get by.


For the last shoot, I was able to mount the 3' section of track to an electrical junction box with the supplied hardware. The track is rigid enough and the attachment to the electrical junction box strong enough, that I could safely attach a 5/8: O.D. stud to the electical box and hold the entire assembly with a knuckle attached to a C-stand. Since I attached the electrical box to the track in the middle, it is balanced around the 5/8" stud which protruded from the middle knock out hole on the back of the octagonal junction box.

For the stud, I used a 3/8" pipe (5/8" OD). To connect the short section of pipe to the box, I used a 3/8" x 1/2" coupler and with a 1/2" x 3/8" bushing that I screwed into the coupler from the inside of the box. A large washer was also needed. It is very secure this way.
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