Halo
A bright ring around lights seen through night vision, like a distant yard light. Smaller halos mean cleaner views near lights.
What it means
When a night vision tube looks at a small, bright light, it shows a glowing ring around it. That ring is the halo. It comes from how electrons scatter inside the tube between its front surface and the plate that multiplies them. It is measured in millimeters on the tube, and smaller is better. One major tube maker’s datasheets list about 0.85 mm typical; many housing sellers publish no halo figure at all.
What it changes in the field
A large halo makes lights bloom into bright blobs that can hide things near them. Think of a coyote crossing in front of a farmhouse light, or a hog near a feeder with a light on it. A small halo keeps the light as a point and the area around it readable.
Halo also affects how a tube handles stars, a bright moon and, for many hunters, the glow of a nearby town on the horizon.
What to look for
- A published halo figure, if you hunt near lights. Few sellers publish one; a per-tube data sheet usually includes it.
- Halo varies by tube design. Some modern tube designs are marketed for smaller halo.
- Autogating helps a tube cope with bright light but does not remove halo.
Halo is separate from figure of merit. A high-FOM tube can still have a large halo.
How we use it on this site
We record the halo figure when the maker publishes one, and leave it blank otherwise.