Shutter Speed / Exposure Tutorial

Author: John Honovich, Published on Nov 28, 2016

Surveillance users do not need to be photography experts but understanding the basics of shutter speed is critical to avoiding major low light problems. In low light conditions, surveillance video can appear blurry and objects will look like ghosts - all due to issues with exposure.

Here is an example:

In this tutorial, we explain the role of exposure and setting shutter speed has in surveillance including a 5 minute video screencast to show you the key issues in action.

Shutter Speed / Exposure

The terms shutter speed and exposure are often used interchangeably but are technically not the same thing.

Shutter speed refers to how long the sensor is exposed to light. Exposure consists of shutter speed ('how long') combined with iris opening ('how wide') but is often simply used to mean shutter speed, leading to confusion. As a practical matter, most surveillance cameras either have a fixed iris or the iris will automatically become as wide as possible in low light, leaving shutter speed as the key parameter to adjust.

In this tutorial, we focus on shutter speed. For details on iris and aperture, see our Lens Iris Tutorial and F-Stop Tutorial.

Automatic Vs. Manual Shutter Speed

Surveillance cameras almost universally default to automatic control of the shutter speed, meaning that the camera will continue to adjust its speed without any intervention of the user. In brighter scenes, shutter speed will be faster (e.g., 1/1000s), but if it is quite dark, the shutter speed slows (e.g., 1/30s).

Get Video Surveillance News In Your Inbox
Get Video Surveillance News In Your Inbox

Users typically may set minimum and maximum shutter speeds to better control how widely the camera may vary its exposure. However, this is not normally required unless issues are visible or manufacturers use poor defaults (such as slow shutter / sens-up, covered later in this post).

Now, nearly all cameras use automatic shutter speed, but manual settings are still used in some specialist applications such as license plate capture / recognition and machine vision.

Range of Shutter Speeds

Shutter speeds can range from extremely fast (1/1,000, 1/10,000 of a second or less) to extremely slow (1/2 of a second or more). Under normal circumstances, since shutter speeds are controlled automatically, fast shutter speeds rarely have negative effects.

However, when using even a slightly slow shutter speed (such as 1/15 second), motion blur may be significant, obscuring details. The threshold where blur occurs varies widely, depending on light level, object speed, and other variables, with no hard and fast rule for what is universally "too slow."

Recommend 1/30s Minimum Shutter

That being said, we strongly recommend against using shutter speeds slower than 1/30s in almost all cases, as blur is likely even on slow moving objects. For faster moving objects (e.g., cars), minimum shutter speeds of 1/60s or higher may be needed to eliminate blur, depending on the speed of the vehicle.

Exposure in Action

Watch the 5-minute video below for a demonstration of different shutter speeds and dealing with slow shutter settings.

Fixed Shutter Speed

IP cameras most often allow advanced controls for fixing the shutter speed of a camera. However, we do not recommend this except in very specific applications.

The most common surveillance application for fixed shutter speed is license plate capture. The images below show the same camera in a license plate capture application, using default 1/30s shutter speed and 1/500s shutter. Using defaults, even at slow speeds (<10 Mph) the camera is unable to capture the plate, while at 1/500s, the plate is clearly legible.

Manufacturer Tricks

Now, most manufacturers allow their cameras to automatically adjust shutter to as slow as 1/30s by default. However, users beware: some manufacturers still default to slower shutters which may cause significant blur in low light even on slow moving objects. See our Camera Slow Shutter / Ghosting Test for details.

Additionally, manufacturers may use other techniques which essentially amount to slow shutter in practical use, such as Sens Up, "Intensifier", or frame integration. Users should beware of these terms, and when in doubt, disable these features to see how performance changes.

Other Blur Issues

Users should also beware of other features in IP cameras which may also cause blur. High levels of digital noise reduction (DNR) used in today's super low light cameras may introduce blur. Additionally, true wide dynamic cameras may introduce blur, as well, as they combine multiple exposures to generate the WDR image, with small movements between. These issues may appear very similar to shutter blur, but they all have different causes. Because of this, technicians may need to adjust several settings to remove blur for best results.

1 report cite this report:

Avigilon Real Time Exposure And Gain on Feb 24, 2015
Knowing how exposure and gain impact image quality, bandwidth, and camera performance can useful in installation and troubleshooting. Very few...
Comments : PRO Members only. Login. or Join.

Related Reports

Installing Box Cameras Indoors Tutorial on May 22, 2018
This tutorial starts our physical installation for video surveillance series, starting with Box Cameras, one of the oldest and most basic types....
Dahua 12MP Fisheye Camera Tested (NK8BR4) on May 16, 2018
Continuing our coverage of 12MP sensor fisheye cameras, we bought and tested the Dahua NK8BR4, examining: Default vs. Optimized...
Installing Cameras in Plenums Tutorial on May 15, 2018
There is often confusion about plenum ceilings, with misinformation about what is required when running cables through them and mounting cameras...
Access Visitor Management Systems Guide on May 11, 2018
"Who are you, and why are you here?" Facilities that implement Visitor Management Systems hope they never need to ask that question to anyone,...
Vivotek 12MP Fisheye Camera Tested (FE9391-EV) on May 08, 2018
Next in our 12MP fisheye camera evaluation, we bought and tested Vivotek's latest generation FE9391-EV, a new model claiming improved smart IR...
Access Control Card Printers Guide on May 03, 2018
Card printers are a core component of professional access control systems, often used as photos IDs and prominently displayed. Modern badges put...
Last Chance - May 2018 Camera Course on May 03, 2018
This is the last chance to register as the course starts next week. This is the only independent surveillance camera course, based on in-depth...
Avigilon 12MP Fisheye Camera Tested on May 03, 2018
12MP fisheye cameras have become mainstream, with nearly every major manufacturer offering their take on this segment. To see how these new higher...
Access Control Levels and Schedules Tutorial on May 01, 2018
Configuring access levels and setting up schedules is central to maintaining facility security. Many people may need to enter areas but most do not...
Hikvision DarkfighterX Vs Darkfighter PTZ Tested on Apr 26, 2018
Hikvision has focused on improving low-light performance for PTZs, an area that has traditionally been a problem, even more so than fixed cameras,...

Most Recent Industry Reports

VMS Server Sizing on May 25, 2018
Specifying the right sized PC/server for VMS software is one of the most important yet difficult decisions in IP video surveillance. In the past...
China: Foreign Video Surveillance Is Security Risk on May 25, 2018
The Chinese government has long acknowledged that foreign video surveillance is a 'risk to national security' and has increasingly and almost...
US House Passes Bill Banning Gov Use of Dahua and Hikvision on May 24, 2018
Today, the US House of Representatives passed H.R. 5515, a bill that includes a ban on the US government's use of Dahua and Hikvision. This follows...
Hanwha Wisenet X Analytics and VMD Test on May 24, 2018
Continuing our updated testing of camera analytics, we tested Hanwha's Wisenet X analytics for over two weeks in multiple scenes, indoors and out,...
Ambitious Mobile Access Startup: Openpath on May 24, 2018
This team sold their last startup for hundreds of millions of dollars, now they have started Openpath to become a rare access control small...
Amazon's "Dangerous New Face Recognition Technology" Says ACLU on May 23, 2018
The ACLU has caused a stir, with a new report Amazon Teams Up With Law Enforcement to Deploy Dangerous New Face Recognition Technology,...
Software Only VMS vs NVR Appliances on May 23, 2018
Should you buy your own PC/server and load VMS software on it or get a turnkey appliance (both hardware and software, e.g., NVR, Hybrid DVR) from a...
Buy Arecont: Top Bid $10 Million Cash on May 22, 2018
Last year, Arecont had a deal for a purchase price of $170 million (see Failed Arecont China Acquisition). This year, Arecont has a deal for a...
Installing Box Cameras Indoors Tutorial on May 22, 2018
This tutorial starts our physical installation for video surveillance series, starting with Box Cameras, one of the oldest and most basic types....
The Hikvision Smart Classroom Behavior Management System on May 22, 2018
Hikvision's rapidly growing offering of analytics, which we most recently examined with Hikvision's ethnic minority analytics, is now going into...

The world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally. Dedicated to independent and objective information, we uniquely refuse any and all advertisements, sponsorship and consulting from manufacturers.

About | FAQ | Contact