What are "lumens" and how are they measured?
Lumens are a measurement of the light produced by your projector's light source, which may be referred to as a "bulb" or "lamp".
Unfortunately, comparing lumen counts on projectors can be tricky. There are many types of lumens measurements, such as "ANSI lumens", "peak lumens", and "market lumens". Even knowing which type is measured can give mixed results, as many companies perform their measurements under non-standardized conditions. That's why it's often better to judge a projector's quality by customer reviews than by comparing their numbers.
In any case, a brighter projector will provide you a clearer decoration in a wider variety of locations, whether light or dark. Any projector can work – but the lower the brightness, the more limited you will be as dimly projected decorations are easily washed out by ambient light.
If you have a projector with a lower lumen count, you can still create some stunning digital decorations; picking out the right decoration for your projector is the key. For example, decorations with shadows and silhouettes such as Zombie Invasion! and Tricks and Treats can look very effective using a projector with a lower lumen count.
The key consideration here is how well you are able to control surrounding light. Street lamps, passing cars, porch lights, and other outside elements will compete with your projector’s brightness, potentially leading to a washed-out display. If you don’t have much light to compete with, projector models with lower lumen counts can work just fine.