Rental houses use lens projectors to evaluate the technical qualities of a lens. Here’s how it all works.
Why would you ever want to shoot light the wrong way through a lens?
If you throw the lens up on a projector, it will shoot a chart out onto a screen. Evaluating the image projected on the screen allows you to scrutinize the lens in a neutral, consistent environment. This is how lens professionals judge glass in a clear manner.
Of course, “perfection” isn’t always the goal with lens design, and there are many aesthetic reasons to choose a wide variety of lenses that come with breathing and distortion. With a lens projector, you can quantify those imperfections; if you wanted to find a set of vintage primes that all breathed the same amount, you could use the information from the projector to help you evaluate your options.
A new video from Cinematography Database shows this process in action:
Here’s the most important information you can glean from testing a lens on a projector.Watch: What You Can Learn from Shooting Light the Wrong Way Through a Lens