Projection Troubleshooting Tips

by | Jun 9, 2022 | Production, Video

By Tim Adams

There are few things more stressful in a tech’s life than equipment that doesn’t work and you don’t know why. Projection issues can be a particular thorn in our sides as there are any number of variables that cause these systems to misbehave. Let’s discuss some common projection problems and how to troubleshoot them.

Problem #1: No Signal

One of the most common issues is the dreaded “No Signal” message after you switch inputs. Not only is this embarrassing, but it’s incredibly frustrating when you can clearly see the device is connected. The culprits most prone to this behavior are computers, and the scenario in which we see this occur most often is when a guest speaker comes in with a device that has never connected to our system. 

Start with the Basics

To start down the troubleshooting path, it’s always good to start with the basics, such as unplugging and replugging the cable, restarting the device and ensuring that the device can output to the resolution of your projection system.

Along with resolution is frame rate, such as the difference between 1080p30 and 1080p60. This small difference can mean the difference between your projection system being able to display signal or not. 

This is one of the reasons I have been standardizing church projection systems on 1080p and HDMI for the last few years. We don’t need to support legacy display standards such as composite video, S-video, component or VGA any more. I’m even suggesting that DVI start to be phased out. Supporting all of those standards simply adds unnecessary complexity, and while a scaler can help, why borrow trouble? HDMI has enough headaches on its own without needing any help from older signal standards.

Move on to the More Advanced Steps

Back to troubleshooting: if you have verified that the “easy” stuff is not the issue, then we have to start diving deeper—does another device work on that connection or cable? If so, the issue lies in the new device you originally connected. If it does not, then there could be an issue with the cable you’re using. Sometimes a different cable can solve your problems. 

A quick note here on proper cable coiling and storage—if you do not know or practice the over-under cable wrapping technique or leave your cables out where they can be walked on, trampled and otherwise generally abused, you’re asking for trouble down the road.  A clean stage should be the norm when a program is done in your church. Or you can just keep buying cables…

If the cable is good, then you could have an HDMI and/or HDCP version mismatch. This can often manifest as a “blinking” image from the device. It will pass signal, but every few seconds, the image will blink to black, which is SUPER distracting.

When All Else Fails

The final step, which may or may not be feasible during your program, is to try connecting the device directly to your projector. If that works, there is an issue in your signal chain between the stage/booth and your projector(s). 

Should those steps not work, it could be time to call in a professional to do a deep dive into your system, as it would seem there is likely something very wrong in the heart of your system, such as with your scaler, matrix, transmission systems, etc.

Problem #2: Image Dim/Washed Out

If your current projection system consistently produces dim or washed out images, you may not have the correct system in place. Projection systems have gotten a bad rap over the years due to the high cost of projectors that are bright enough to provide the image quality and brightness we want, but that is an issue no longer. The last 5 years have seen a dramatic drop in pricing for high lumen projectors that can give you the image you need. However, if you don’t know how to figure out how bright a projector you need and the size screen you need, you will likely still be disappointed in what you get.

Determining the Correct Screen Size

Fortunately, this information is pretty easy to calculate. I always start with the screen size because the brightness you need is based on the square footage calculation of your screen. 

There are two schools of thought when it comes to calculating screen size: the first method relies on calculating the height of text on the screen from a given viewing distance; the second method relies on maximum viewing distance to the screen. The latter formula is what I use and it looks like this: you find the seat in your sanctuary that is farthest away from the screen and measure the distance from that seat to your screen (use feet as your unit of measurement). Divide by 8 and you will have your screen height (minimum height—don’t go smaller). 

To figure out the width, we first need to know what aspect ratio or resolution our projection system will be. To achieve this, we divide the first number in the resolution by the second number (e.g. 1920/1080=1.78 or 16:9 aspect ratio). We can then multiply our height number by 1.78 if we’re using 1080p and we’ll get our width number. 

So, the formula would look like this for an 80ft. max viewing distance: 80/8=10*1.78=17.8ft. width for a screen measuring 17.8’W x 10’H. 

We can then also get the diagonal by using the Pythagorean theorem to solve for the hypotenuse or diagonal measurement. We need this information as projection screens are often measured in both the diagonal measurement and the aspect ratio, so it’s good information to have on hand when ordering.

Determining the Correct Projector for the Screen

Now that we have the screen size, we can use a simple square footage calculator to get the square footage. Then, we can plug that number into a simple formula to discover how bright a projector we need.

projector lumens / square footage * screen gain = foot-Lamberts

Foot-Lamberts, or fL, are units of measure for reflected light and are incredibly useful for our purposes. For reference, a completely darkened movie theater is going to have an average fL measurement of 16fL. You might think this is plenty bright for you, but ambient lighting can have an incredibly significant impact on your screen. Thus, I always recommend aiming for a minimum of 50fL for spaces that have a good control over ambient light levels. If you do not have that control, aim for 70fL or higher.

To use our numbers from the screen size exercise above, we can calculate that a 17.8’x10’ screen is going to give us 178 square feet. Now we start playing with the lumen variable in the formula to find the right brightness:

2000 lumens / 178 sq. ft * 1.0 (screen gain for matte white screens) = 11.2fL (way too low)

6000 lumens / 178 sq. ft * 1.0 = 33.7fL (better, but still too low for my taste)

8000 lumens / 178 sq. ft * 1.0 = 44.9fL (bare minimum for my comfort levels)

You can see how quickly your projector costs can rise due to the size of your screen, but I do want to stress how important it is to have the right size screen for your space. Your screen is an investment that will last for a long time and should not be something you scrimp on; it’s not unlikely that your screen will outlive 2 projector upgrade cycles and a good laser projector could last a church 10-15 years, so that’s something that is worth thinking about.

Resources and Helpful Hints

Below are some of the resources I use when figuring out how large a screen is needed and how bright a projector I need: 

Square Footage Calculator:
https://www.calculatorsoup.com/calculators/construction/square-footage-calculator.php

Hypotenuse Calculator:
https://www.omnicalculator.com/math/hypotenuse

Something else to consider: I always recommend using blue painter’s tape to mockup the screen size and stand in different places in your sanctuary to see how it looks for people at different distances. This can be useful to show leadership so they understand how large the screen will be. In my experience, the screen size required is almost always significantly larger than people think.

Problem #3: Image Too Small/Large For Screen

Similar to being able to calculate how bright a projector you need and how large a screen size you need, knowing the proper distance the projector needs to be from your screen and where it should be located is fairly easy. 

Distance from Screen

Rather than bore you with formulas, I would recommend you simply do a Google search for your projector’s make and model, then click on the result for ProjectorCentral.com. This will bring up a webpage where you can find an option for “Calculate Throw Distance,” which will allow you to easily find the distance your projector needs to be from your screen based on the screen size and aspect ratio. (Are you seeing why I go in the order I do to find out viewing distance, then screen size, then projector brightness? You need this information to find the next data point.)

Modern laser projectors do come with features like keystone correction, image warp, geometric correction, lens shift, optical zoom, etc., however, using these does have an impact on your overall image brightness—as much as 20%! So, it’s important to understand where the projector needs to be in both the vertical and horizontal axes.

Location, Location, Location

How far away from the screen is just as important as where the projector needs to be in relation to the top of the screen (called “offset”). Most often, when hanging a projector, it needs to be aligned with the top of the screen; however, it’s not an absolute rule—factors such as the type of lens you’re using and throw distance can affect this placement. 

Bringing It All Together

We have reached a place in our society where projected images are expected to fit the screen fairly well—an image that is a little too large is better than an image that doesn’t fill the screen. But let’s collectively make an effort to raise our game and do better. The tools to achieve this next level in quality in our projection systems are readily available. It just takes a little time and effort on our part to bring out what could be, in some cases, a significant change without having to invest in any new equipment or infrastructure. 

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