Fun times doing blended projection with Barco 0.4 UST Lenses

Just wrapped my first show of the year and thought I would share my recent experience with the Barco 0.4x Ultra Short Throw (UST) Projection lens. I've used these lenses for single shot rear projection before and they can be a super tool for tight projection spaces. This show was with a new client and they had placed the shortest lenses they had in their CAD software (.67) on the drawing. That was going to be tight. But not the worst scenario I've encountered. I didn't find out until a few days before the gig that I would be using these even shorter lenses. I'm not going to sugar coat it, I was a bit apprehensive to be performing a blend with them.

When I arrived on site, they only had a single buck of scaffold so I instructed the hands to stack a roadcase on the scaffold in order to get me a bit closer to center. But once the screen was flown, the end client decided to lower the screen eight feet to use it more as a backdrop than over the heads of the presenters, so I ended up slightly above center. Not ideal for hotspotting, but still workable. Yes, there were very visible hot spots on the Stumpfl dual vision matte. But the end client thought it was absolutely amazing and didn't notice at all. Being able to fill a 30ft wide screen with only seven feet of rear projection distance was impressive to me too!

We opened the cross rental lens cases and discovered that one lens had a mounting plate for the electronics connector and the other just had the connector loose. Not reassuring, but not the first time I've seen this. When I went to install the lenses, they would only line up with the lens pointed straight down. Hmmm, I didn't want to rotate the xenon based projectors on their sides. So I finally set my male tendencies aside and downloaded the installation guide on my phone. I usually read the manuals on new gear. But I had used these lenses before. Here I discovered that the lenses can be oriented to fire up, left or down. that's cool for when you want to project on the floor or ceiling, which I've done. And you have to rotate the motor assembly in different orientations depending on the model projector. The UDX series has the motors up, while the HDX orients them to the side. I'm really glad that I wasn't stubborn and downloaded the manual at this point because there is no obvious or simple way to rotate the motor. Barco couldn't engineer a simple slide lock, thumb screw, or even a sticker to point to the six or eight 2.5mm allen screws that have to be removed in order to reorient the lens. I guess they, like so many other manufacturers, plan on their product being installed once. The other times I had encountered these lenses was pre-UDX, so they had always showed up the left orientation. Another note that is in bold in the manual is that the mirror causes the image to be flipped. So you have to select ceiling front when orienting ground rear, and vice versa. It also made all of the lens shifts opposite too. I thought you might find that as interesting as I did.

Next I discover that the lens with the missing mounting plate also seems to have ED. It's lived a rough rental life and loosely droops down about 15 degrees. I had two other experienced techs check behind me to make sure I hadn't done anything wrong. What I learned now was that when the lens droops. It doesn't simply project lower on the screen like traditional lenses. It rotates the image about 40 degrees when it droops that much. So now I have to McGyver a solution to support the front. Again, not the first time with cross rented lenses. Usually a DI box or door stop will solve this. If it's a bit low or high I can crank the feet up and get it lined up really close. However, with the rotation going on, even an eighth of an inch rotated the image about five degrees. In general, when using these lenses. the slightest adjustment equals a significant outcome. I'm lucky that the audio team was supporting a band and had the perfect height adjustable mic stand. So I lock in the exact height I need. It takes a bit of trial and error as I have to take the mic stand out to shift the lens, then put it back in and re adjust it five or six times to end up cornered in without hardly any overshoot. Patience is a virtue in this business.

Next step is focus. This lens, like most other ultra short throw lenses has a distance setting. Sort of a corner focus setting. Unfortunately for our small market in the US(note the sarcasm), the distance is indicated on the lens in meters. So I do some rough mental conversion math to dial that in and use the motorized focus with the remote to focus up the center. This lens changes image size significantly as you focus too. So it took a bit of trial and error to get it focused and zoomed to the right size. Especially with my new mic stand helper.

Finally the warp game begins. This client didn't provide any network gear and this was honestly too simple of a blend to warrant cabling it all up. So I used XLR cable to plug in one of the new black glossy remotes. Wow these are super nice! Barco stepped up their remote game with these. The Barco warp interface is very icon based so don't even attempt to do a blend without understanding what these icons mean and ideally having some training. Both of which I have, so I was able to knock out the blend alignment in about 30-40 minutes from this point. With normal zoom lenses, I will often pick the better of the two projectors and nudge the warp on the other to match leaving one side hopefully not warped at all or only minimally. With these lenses, the angle of incidence from the lens to the screen is so sharp, that the image spread is exponential. So the grid lines spread as they go across the screen. And each projection image is spreading opposite the other meaning none will line up unless you find the exact center of the blend and warp both images to that common point. This took a bit of trial and error. but eventually I was able to fully lock in a very good alignment with only nine adjustment points per projector (3x3) out of the 1,024 potential adjustment points the warp board offers. If you are new to warping projectors, always start with as few points as possible. It makes touch ups when they redo the drape and you have to start over on day two much easier. Ha ha. Yes, that did happen too.

While this wasn't the simplest projectionist gigs I've done. There were also other screens on this show. Then I was asked to run GFX/powerpoint. OK...?!?. Overall, it was a good way to kick off the year. A good time with a fun new group of guys and I learned a few things from the experience that I thought you might enjoy hearing about. I certainly enjoyed recounting the experience. All names were intentionally left out to protect the innocent. And guilty too ha ha!