Hi,
Just purchased a CCTV camera with a Sony IMX317 sensor and a 2.8-12 C mount lens. Brand is 'ELP'.
At nearly all focal lengths there are dark patches at the edges of the image. See attached. These edges disappear when you zoom in (10-12mm).
Has anyone seen this issue before and know what causes it?
The lens has 1/2.5" printed on it, and the IMX317 sensor is listed as 1/25" also, so it's either;
1) A badly made lens, or
2) The lens it mounted incorrectly (it is screwed all the way in), or
3) All 2.8 varifocal wide angle lenses look like this.
This normally happens if the sensor size is larger than the lens is designed for, so the focused image is smaller than it needs to be. I have no reason to suspect the sensor as it outputs QHD at 30fps. It probably is an IMX317, which leaves the lens, or the mounting distance.
I know that these types of lens also come in 'HD' and '3MP' variations (mine isn't either), which presumably means the optics are better, but that shouldn't cause the dark edges AFAIK.
Thanks.