Normalize Exposure Settings for IP Camera ComparisonsBy John Honovich, Published Dec 22, 2009, 07:00pm EST
We recommend all surveillance camera comparisons be performed with normalized exposure settings to ensure fairness and eliminate 'games'. Starting immediately, we will use 1/30th and 1/8th second exposure times as standard settings to test and compare cameras. This is especially critical in the assessment and measurement of low light performance.
Why This is Important
In testing a wide range of cameras, it has become clear that manufacturers select a wide range of default maximum exposure settings. While there are valid uses for different settings, those manufacturers who choose longer defaults for maximum exposure settings are viewed unfairly as having superior low light performance. For background on this issue/trick, review our testing and analysis of exposure's impact on low light video quality.
Maximum exposure settings can have a dramatic impact on 'visible' image quality because changing it from 1/30th to 1/8th or 1/2th can increase light captured by 400% to 1500% - a dramatic difference that overshadows practically any other setting.
Comparing still images from one camera with 1/30th s exposure to a 1/2 s exposure will always be unfair and almost always lead to the 1/2 s exposure camera being viewed as better (because manufacturers will show still objects hiding the problem of motion blur).
Here's a clear visual on image tradeoffs from varying exposure settings that you would almost never see from a manufacturer:
Why 1/30th and 1/8th Second Exposure Settings?
1/30th second exposure matches the maximum frame rate and is a commonly used setting by manufacturers. It's also generally the shortest maximum exposure setting we find in IP cameras that we are testing.
1/8th second exposure provides a significantly longer exposure increasing both the 'brightness' of a dark scene and the risk of motion blur. We think 1/8th is a good intermediate point - much lower and motion blur is guaranteed to be strong.
Not all cameras allow for direct setting of their maximum exposure time. Some only allow indirect qualitative settings.
Other cameras offer special modes for very long exposures - 1/2s or even 1s exposures.
We will make note of either circumstance and provide additional, clearly marked tests of such modes.
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