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".
Measuring lumens can be tricky. There is no industry standard which controls the specification of "lumens", also referred to as "market lumens".
Final brightness output depends so much on environment that it is difficult to compare brightness relying on numbers alone.
Further complications occur because other factors of your projector's construction can affect the final brightness output you experience. These factors can include such as lenses, mirrors, and light-spill.
Because of these barriers to consistent measurement, we recommend looking for measurements in "ANSI lumens". ANSI lumens are an industry standardized measurement set by the American National Standards Institute, which provide a more accurate measurement than non-standardized market lumens.
Even if you're using ANSI lumens, measuring light levels can be very tricky.
AtmosFX recommends a projector of at least 300 ANSI Lumens (which translates to about 1800 market lumens), although many projectors of lower brightness will work fine.