Zez Retro

Lag testing in a 1700 seat theatre

As part of my day job, I present Stand Up comedy events and occasionally we get to work with some well known names. In this case it was two nights of the John Cleese show in Tallinn.

On the second day the theater was setup and no preparation was needed in the afternoon. That is a ~1700 seat theater with a big rear projection screen setup and technicians on hand to help me. Why let that go to waste, I thought I would lag test the projector and then connect my MiSTer and play a few rounds in a unique environment.

The setup was a projector mounted behind the screen to enable rear projection. The projector model was Panasonic DLP PT-RZ21K with a native resolution of 1920 x 1200.

Lag testing a projector is fairly straightforward, you need to hold the Time Sleuth in front of the picture and line it up with the blinking white blocks of light. The technicians gave me the idea to mount the Time Sleuth onto a mic stand to hold it in place in front of the projector. It also works fine being powered from a USB battery.

This setup did work but I noticed that the angle you mount the time sleuth seems to matter, so if you can’t get it to read move it around a bit. Also the external lighting in the room matters, the Time Sleuth works best here when I turned out the lights in this area of the stage.

The results were a welcome surprise, the projector gave a response time of ~21ms across all progressive resolutions, 1080p, 720p and even 480p. 480i gave some wild measurements but you really shouldn’t be sending an interlaced signal to this type of projector anyway. If you are using original hardware, use something like a RetroTink 2x to line double the 480i to 480p and you will get an immensely better result.

The low lag is surprising as while this is a industrial quality projector which costs more than a nice car, it’s designed for video environments where sub-frame latency is typically not needed. When this is used in a theater or outdoor event, it’s usually to show video, not to play games, so response time doesn’t have to be so small.

However 20ms is very respectable, being just over 1 frame of lag at 60fps.