Refresh rate
How many times per second the picture updates. 50 or 60 times a second looks smooth; lower rates stutter when you pan or a coyote runs.
What it means
Refresh rate, or frame rate, is how many new images the sensor produces each second, measured in hertz (Hz). Most current hunting thermals run at 50 Hz, a good share at 60 Hz, and a few at 25 Hz. Some units sold for export are limited to 9 Hz by export rules.
What it changes in the field
A higher rate makes motion smoother. When you sweep across a field, or a coyote trots in to the call and then breaks into a run, a low rate shows the image in steps and the animal can seem to jump between frames. That makes it harder to track and to hold the crosshair on a moving target.
The difference between 50 and 60 Hz is small for most hunters. The difference between 9 or 25 Hz and 50 Hz is easy to see.
What to look for
- 50 Hz or better is the common advice for running coyotes and for scanning by hand.
- For a scope used mostly on still or slow animals, such as hogs at a feeder, anything above 30 Hz is generally described as usable.
- If a used unit is unusually cheap, check that it is not a low-rate export model.
- Some units let you drop the rate to save battery; the published figure is the maximum.
How we use it on this site
We show the maker’s figure in the spec table and score higher as better.