With the market sharply moving to megapixel cameras, an increasingly important question is: what MP cameras offer the best low light performance? In this report, we answer this question based on months of field testing. We then take the best performing megapixel cameras and test them against a top SD camera to see how big and what type of performance gap exists between the best low light megapixel cameras and SD cameras.
Fair Tests and Manufacturer Tricks
If you take megapixel cameras out of the box and test them for low light performance, the results will be badly skewed - guaranteed. The reason is that manufacturer's default maximum shutter speed vary widely. This is critical because shutter speed determines how long light is captured by the camera. Some manufacturers default to 1/30s, others as low as 1/6s. A camera with a 1/6s default shutter gets 500% more light than the camera with the 1/30s exposure (all things being equal). There is no fundamental difference or technology superiority, just a choice for default.
We strongly recommend that all camera tests use normalized shutter speed to make sure that no camera has an unfair advantage based simply on how aggressive their default settings are. And remember, longer shutters can have very bad side affects - specifically motion blur / ghosting. We normalize all cameras to 1/30s shutter for our tests as this matches the normal top frame rate (30fps) for surveillance cameras. You could certainly choose a different level - all images would be brighter (or darker) depending on the level but the relative performance would remain the same.
Secondly, it is imperative that cameras be tested simultaneously and under recorded light levels. It is very easy to mistake one camera as being better than another when testing cameras at different times. Most frequently, the problem we see in industry reviews is that the light levels change between tests and the tester/reviewer is unknowingly comparing Camera A's performance at 1 lux with Camera's B performance at 2 lux, drawing erroneous conclusions.
Over the last few months, we have done numerous tests - indoors in a dark environment and outdoors at night to determine relative performance. We've tested Arecont, ACTi, Avigilon, Axis, Bosch, Pelco, Panasonic, Sony, Vivotek, etc.
UPDATE: We've taken the top performers of this test and did a shootout against Axis's new Lightfinder camera / Q1602.
Here is a sample of the format we use inside to contrast image results and demonstrate differences:
Inside, we examine the results, show image comparisons and then compare to SD.