Film-Tech Forum ARCHIVE: Choosing a Digital Projector for a Drive-In

This is topic Choosing a Digital Projector for a Drive-In in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Barry Floyd (Member # 385) on 04-03-2012, 01:49 PM:

We plan on do our conversion from 35mm to digital later this year and I'm now starting to get quotes on the machines and installation costs.

I've got the projectors narrowed down to 2 specific models - the Barco DP2K-23B and the Barco DP2K-32B. Both of my screens are 25 feet x 59 feet, with a throw of 354 feet. The 23B maxes out at a screen size of 75 feet with a 4kw bulb. The 32B can do screens up to 105 feet with a 6.5kw bulb. Since 4kw digital is brighter than my existing 4kw from my Xenex I lamphouse, will I be fine with the 23B? Most of the dealers I've spoken with are steering me towards the 23B. I know the 32B will give me WAY more light than I need, but I'd rather not spend the extra money if it's not needed. Don't really plan on doing 3D, so not really worried about loos of light from that.

Any thoughts?

Posted by Manny Knowles (Member # 1171) on 04-03-2012, 02:15 PM:

Are you planning to show 3D? [Cool]

Posted by Barry Floyd (Member # 385) on 04-03-2012, 02:36 PM:

No. From what I've seen so far, the only 3D system that actually works in a drive-in setting s is the Dolby 3D with the reusable glass - mainly because of the lack of needing a silver screen surface.

Posted by Sam D. Chavez (Member # 1841) on 04-03-2012, 02:49 PM:

I don't believe there is no such thing as too much light in a Drive In, but you're the owner.

You will no doubt find a use for the extra light and the resale value might be better down the road if your plans change.

Yo should make sure there is a suitable lens for your throw.

I like all the Barco's, but Christie is a good rugged projector with plenty of light as well.

Posted by Barry Floyd (Member # 385) on 04-03-2012, 03:16 PM:

Some have said that too much light on a drive-in screen will bring out any and all imperfections in the screen surface.

Another owner in Ohio last week installed a 32B and they shot a 25.7 reading on the light meter with the 6.5kw lamp on an 83 foot screen. They cranked it way down, but he's still a little over 14 f.l.

Last quote I got, they "calculated" I'd get 13.7 with flat and 10.3 with scope using the 23B. I'm sure that's probably way more than I'm getting now, but it's still not 14fl. I do not plan on taking the 1/2 drive-in VPF's, so I doubt it would be an issue.

Posted by Scott Norwood (Member # 30) on 04-03-2012, 03:25 PM:

Out of curiousity, how do DIs that use the Dolby 3D system make sure that they get back the correct number of glasses per car, given that one car may contain a variable number of occupants?

I guess that the good part (at least for those not doing carload pricing) about 3D at a DI would be that it would eliminate the people-hiding-in-the-trunk problem. [Smile]

Posted by Barry Floyd (Member # 385) on 04-03-2012, 03:49 PM:

Scott, I've only seen it at one theatre and that was at the Galaxy Drive-In in Ennis, Texas. I went down to Dallas for the DITA meet back in November, met Brad and Jeremy from Film-Tech and we all (the whole group) took a trip down to the Galaxy one night.

If I remember correctly, when you buy your tickets, and if you have 5 people in the car, they give you 5 pairs of glasses and a laminated card with the number "5" on it. When you leave the theatre for the night, you have to drive by the glasses collection station and you have to give back the number of glasses printed on the card.

That drive-in has the full commercial dishwasher and drying racks for the 3D glasses in a ground floor room below the projection booth. It was a pretty efficient set-up.

They were running Series 1 Christie projectors when I was there back in November.

Posted by Brad Miller (Member # 2) on 04-03-2012, 04:25 PM:

Remember your drive-in screen is NOT a 1.0 gain, so you need more to achieve the same result.

Barco is really the best option for a drive-in due to the sealed light engine.

Posted by Sam D. Chavez (Member # 1841) on 04-03-2012, 05:48 PM:

Brad is right for sure regards the screen gain. The gain could be anything from maybe 1.0 with white paint to way less depending on the age of the paint job, etc.

"Another owner in Ohio last week installed a 32B and they shot a 25.7 reading on the light meter with the 6.5kw lamp on an 83 foot screen. They cranked it way down, but he's still a little over 14 f.l."

I seriously question this figure. Did they use some sort of silver paint perhaps?

Posted by Carsten Kurz (Member # 5396) on 04-03-2012, 06:38 PM:

Lamps lose brightness with aging, so, go and do yourself and your patrons a favour and get the 32B. The windshield will eat some light as well, so the normal 14-16fL measured outside the car is not practical anyway.

Also, more light on the screen might give you a real chance for some extra shows.

- Carsten

Posted by Brad Miller (Member # 2) on 04-03-2012, 07:37 PM:

Agreed Sam. Although the Barco 32B is the brightest projector available, 25.7 footlamberts on an 83 foot drive-in screen surface tells me something isn't stirring the Kool-Aid with those numbers.

Posted by Louis Bornwasser (Member # 3063) on 04-03-2012, 08:35 PM:

Earlier starts (in June) equal more money, equals more satisfied customers (for later in the season.)

Once I tried to "size" drive in lamphouses (on film). I was wrong: On film 4500 watts with the best projector and the best lenses and the screen angled and painted properly is the only answer. Since the delivery medium (digital) is not relevant, the basic idea still holds.

Wouldn't you sell more family tickets if you started at 8 pm that you will at 10 pm? Act accordingly. Louis

Posted by Steve Guttag (Member # 268) on 04-03-2012, 09:32 PM:

If your screen had a 1.0 gain AND you were able to obtain a lens suitably long for your "flat" picture...I would predict you would need over 38,000 lumens for scope and 24,000 lumens for flat...even with an anamorphic lens, you would need about 31,200 lumens for scope. My recommendation get the bigger projector....again, I don't know where you are going to get the 7.47 TR lens for flat. Barco's lens line tops out at 5.5 and they don't have an anamorphic option.

Posted by Monte L Fullmer (Member # 2797) on 04-03-2012, 11:51 PM:

quote: Steve Guttag
My recommendation get the bigger projector....again, I don't know where you are going to get the 7.47 TR lens for flat. Barco's lens line tops out at 5.5 and they don't have an anamorphic option.

Prob the only way to get under these numbers is to build two small projection buildings that are closer to the screen - more like getting a 200ft throw to the screen with those screen measurements.

Then you can, maybe, play with the 23B idea, but the 32B will give out excellent results due to that the gain of the screen, as Brad mentions, will not be the 1.0 needed along with you be outside with the elements of stray light, dusk situations and so forth.

Brighter is better. - Monte

Posted by Scott Norwood (Member # 30) on 04-04-2012, 10:24 AM:

Steve--out of curiousity, how do you get those numbers?

I would have done (image area in sq. ft.) * (desired luminance in fL.) * (screen gain).

That gives me:

(25 * 1.9) = 47.5 * 25 = 1187.5 square feet for flat image

1187.5 * 14 * 1 = 16625 lumens needed for 1.85 image at 14 fL on 1.0 gain screen)

(25 * 2.35) = 58.75 * 31 = 1821.25 square feet for scope image without anamorphic lens

1821.25 * 14 * 1 = 25498 lumens needed for 2.35 image at 14 fL on 1.0 gain screen

I did not account for the chance that longer lenses are probably slower than the "typical" lens that is used to measure light output, and that manufacturers' claims of brightness are often overstated. I also did not account for bulb aging. Do those three factors explain why your figures are 50% higher than mine? Or am I missing something else?

Edit: It looks like Christie has lenses that would work in Barry's case, if he isn't committed to Barco.

Edit 2: Something is wrong here. The Barco web site says that the DP2K-23B puts out 24,500 lumens, but is good for a 75ft. wide screen? Huh? Even using my numbers, it would be marginal for Barry's screen, even if it were 1.0 gain.

Posted by Barry Floyd (Member # 385) on 04-04-2012, 01:48 PM:

>>>D-Cinema DCI 2K prime zoom lens, 5.5-8.5:1 (HB) for Barco<<<

That's the lens I had quoted for the 23B. Now after listening to you guys, I am leaning more towards the 32B.

I'm not "committed to Barco, but as Brad referred to above, they are the only projector manufacturer with a sealed light engine. In my building, my projection rooms are literally 12 feet away from the kitchen with grills, fryers, etc. Although we have huge exhaust hoods in the kitchen, having the sealed light engine is a BIG deal to me.

Posted by Sam D. Chavez (Member # 1841) on 04-04-2012, 02:45 PM:

I think you are on the right track regarding the sealed light engine.

I have one cinema with DP2000 that draws all its air up the stairs from the snack bar and the city street and everything gets very oily and dirty, but the picture chugs along fine.

Just make sure of the lens size.

Posted by Monte L Fullmer (Member # 2797) on 04-04-2012, 05:14 PM:

Let's see: 354 ft, throw length, divided by 59, the width of the screen, gives out a lens factor of "6" ... 32B should work fine for Barry.

Posted by Steve Guttag (Member # 268) on 04-04-2012, 11:17 PM:

Scott,

I do account for lamp aging, color correction, port hole losses...etc...you know...the real world.

When the manufacturers want to claim a particular sized screen...they almost always are using a 1.8 gainish screen as their reference.

As to the lens...Only Christie uses the HB (High Brightness) designator. I would verify that Christie/Barco or whomever actually has the long lens and just how the projector is supposed to deal with it (Barco, for instance, wants to know the model so it can set the shift/zoom limits as well as to know how to interpret the servos on the various lenses).

Posted by Cameron Glendinning (Member # 3516) on 04-05-2012, 01:50 AM:

Barry does the sun set behind both your screens?

Posted by Barry Floyd (Member # 385) on 04-05-2012, 09:16 AM:

Actually my screens go North / South

Here's a GOOGLE MAP link to our theatre. You can see on the satellite view how the screens are laid out.

Posted by Monte L Fullmer (Member # 2797) on 04-05-2012, 11:42 AM:

Making the south screen getting darker quicker than the north one during the summer...

Like the traffic control layout, esp. with the north screen.

Posted by Barry Floyd (Member # 385) on 04-05-2012, 12:22 PM:

Yeah... Screen 1 (North Screen) was built with borrowed money, whereas Screen 2(South Screen)was built 2 years later with cash. When the cash ran out... we were done.

In the original design, the south side was supposed to be a mirror image of the north side, but when we started excavating the hill to the west side of the lot, it was solid rock. Since we didn't have the cash on hand at the time to blast off the side of the hill, we rotated the whole field 23 degrees off the center-line and ended up putting the screen supports in the middle of the stormwater detention pond. The projector in the south booth shoots out the port hole at the same 23 degree angle, but the image hits the screen surface at a true 90 degrees to the new center-line.

In the future I want to put in parking ramps on screen 2, rework the driveways, add more parking posts, and more landscaping. It's always a work in progress.

Posted by Louis Bornwasser (Member # 3063) on 04-05-2012, 02:57 PM:

Proper design for drive ins: screens always on the West side to allow earlier start. Louis

Posted by Barry Floyd (Member # 385) on 04-05-2012, 09:00 PM:

Kinda hard to run the screens east to east when the property runs north and south, and we weren't allowed by the city to have the screens facing the road.