Infared Camera

I have 4 infrared camera in BH. Initially the images quality were very good. See the pic below.

After sometimes the images getting blur and blur (see picture below for frame 1,3 and 4). I tired to clean the len but the images only improved a bit. I thought because the camera are lousy then I bought a better quality IR Camera to try (see frame 2). The quality of the image is proven better than the original camera when it is new.

Below is the spec of new camera that I am using. It is a water proof camera with resolution 420 TVL. Another important spec is the Min Illumination = 0 LUX (W/ IR LED). I have seen some camera require 0.xx amount of light to work properly.

After I installed the new IR camera, I took a close look on my old camera. I found out that the dirt or dust that make the camera image blur are actually from the inner side of the len. I opened the len and use dry tissue to clean the len surface. The images are much better now although still not as good as when it is new. But is usable.