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You are currently viewing Should I Use a 2.8mm or 4.0mm Lens?

Should I Use a 2.8mm or 4.0mm Lens?

Security Camera Lens Types

In the security industry today, there are two common lens types used: Fixed Lens and Varifocal Lens. For fixed lens, you will often find them in two common varieties; 2.8mm and 4.0mm. In this case, the amount of mm is referring to the focal length of the camera lens. A shorter focal length (2.8mm) results in a wider angle shot, while a longer focal length (4.0mm) results in a narrower shot.

Next, we have the varifocal lens type. When a security camera with a varifocal lens type is chosen, the focal length can be adjusted to capture the angle of choice. Most commonly these will be either 2.8-12mm or 2.7-13.5mm lenses.

A visual example of how longer focal length results in a narrower field of view

Testing Fixed Lens Types – Camera Hardware

To demonstrate the difference between a 2.8mm vs a 4.0mm lens, we installed two cameras in front of our office. The cameras we chose to install were Uniview’s 5MP LightHunter dome cameras: IPC325SB-DF28K-I0 & IPC325SB-DF40K-I0.

These are standard fixed lens domes with an IP67 rating for outdoor weather resistance and LightHunter technology for excellent image quality in low light environments. In terms of lens focal length and viewing angle, here is how the two cameras compare:


  • Resolution – 5MP / 2880*1620@30fps
  • Lens – 2.8mm Lens
  • Angle of View (H) – 96.1° / Angle of View (V) – 55.3°


  • Resolution – 5MP / 2880*1620@30fps
  • Lens – 4.0mm Lens
  • Angle of View (H) – 78.7° / Angle of View (V) – 44.9°

Difference in Viewing Angle (H) – 17.4° / Difference in Viewing Angle (V) – 10.4°

Image Comparisons – 2.8mm vs 4.0mm Lens

First, we have a snapshot from the 2.8mm lens camera for our reference. The camera quality is sharp, colours are vivid, and the angle is wide enough to completely cover eight parking spaces.

Snapshot from Uniview IPC325SB-DF28K-I0 in front of our office | 2.8mm lens

Next, we took a photo from the 4.0mm lens dome camera for comparison. The camera quality is just as sharp as before, however now we are covering a smaller angle. This camera is able to cover about six parking spots.

Snapshot from Uniview IPC325SB-DF40K-I0 in front of our office | 4.0mm lens

Finally, we compared the level of detail in the two shots by enlarging the snapshots and comparing them side-by-side. There is definitely a noticeable increase in fine details from the 4.0mm lens camera. You can almost read “www.uniview.com” from the poster on the right side, while on the left side it’s completely obscured.

Side-by-side comparison 2.8mm (left) vs 4.0mm (right) lens

Final Thoughts

If you’ve ever wondered what the difference was between a 2.8 and 4mm lens, I hope your curiosity was satisfied by our demonstration. Overall, it’s about a 20% difference in viewing angle and image quality between the two lens types.

For suggestions on which lens type to purchase for your project, or other related inquiries please contact XLR Security via email info@xlrsecurity.com or phone 905-794-5508. We look forward to helping you with any security related business or activities!