FAQ — Trail cameras

The short-answer companion to How trail cameras work and Choosing the best trail camera, preserved from the Handykam help section.

What trail camera should I buy?

It depends on what you plan to film, and what quality and features that needs. Think about the subject first — that determines the camera. Once you know roughly what you are filming, look at the features. If you are unsure, or you expect to film several different things, choose a camera with a broad set of features rather than a specialist one. Things to consider:

• Quality against cost
• Trigger speed
• Trigger distance and infra-red range
• Extras such as a playback screen, adjustable sensitivity and external power

What is interpolated resolution?

Every trail camera has a light-sensitive chip that records at a certain actual resolution. Many cameras also quote an "enhanced" or interpolated resolution, where software processes the picture and enlarges it — typically doubling the stated figure — so images and video can be blown up further. Most cameras have this as standard, and it is not dishonest in itself, but it is not extra detail. Anything quoting around 5MP actual, or 12MP interpolated, is in reasonable territory; the higher the actual figure the better.

What is an IR filter pass?

Natural daylight contains infra-red. Our eyes block it, which is part of why daylight colours look as they do. A camera sensor does not block it, and left alone would render daylight scenes with washed, faintly pink colour. So a daylight-capable camera puts a physical infra-red cut filter in front of the sensor, giving richer and more accurate colour.

But at night the same camera needs to see infra-red, because that is what its own illumination produces. So the filter moves mechanically out of the light path when the light level drops, and back again at dawn. That movement is the faint click you hear from a camera at dusk, and the brief reddish cast just before it switches is the sensor working with the filter partly out of the way. Almost all trail cameras and most nest box cameras have this. It is normal behaviour, not a fault.

What memory card do I need?

A card fast enough to keep up with video recording and large enough for the length of deployment. A slow card can delay the camera between triggers, which effectively worsens its trigger speed. A card that fills up simply stops the camera recording — most trail cameras do not overwrite by default, unlike most nest box network cameras.

How long will the batteries last?

Anything from a few days to several months, and the honest answer is that it depends almost entirely on how often the camera triggers and how much infra-red night video it shoots. Illuminating a dark scene is by far the most expensive thing the camera does. For a fixed position near a building, an external power cable removes the question entirely.

Will the camera scare the animals?

Infra-red illumination is invisible and does not startle. What does affect behaviour is human scent and disturbance around the camera position, and — with low-glow units at very close range — a faint red shimmer that some mammals notice. Site the camera, then stay away from it.

Why is my camera taking hundreds of pictures of nothing?

Almost always vegetation moving in front of a passive infra-red sensor while warmed by the sun. Clear the detection zone, reduce the sensitivity, and avoid pointing at open sunlit ground. The second most common cause is pointing the camera at the sunrise or sunset.

Can I use a trail camera for security?

Yes, and many people did. Trigger speed becomes the dominant specification, and a lock and cable becomes essential. Be aware that a camera recording people, particularly beyond your own boundary, engages data protection law — see the ICO's guidance. For a permanent installation, conventional CCTV is usually the better tool.

Related pages: How trail cameras work · Choosing the best trail camera · Wildlife camera glossary