Arecont IP AV3155 lens query

[videoprofessional]

I have recently set up a V8.3Hybrid with 16 analogue and 2 x Arecont AV3155 3mp body cameras. I am using 2 x 6mm manual Megapix lenses. The environment is outdoor for both so the on scene lighting is dynamic. I have found the setup to be straightforward, no problems with GV seeing the cameras etc, however it has taken an age to get the cameras focused. After changing the back-focus and adding/removing spacer rings etc, I have one of the cameras perfect now, and the PAP view makes a great change compared to the usual washy analogue PAL images. however the second camera is proving very hard to focus despite may attempts to get a sharp image. I have tried to keep the aperture setting at as low a setting as I can in order to maximise depth of field, I have tried opening the grub screws on top and bottom of the front plate of the camera housing to move the base focus position of the lens, I have added and removed the spacer rings, etc. I have requested a new lens (8mm) this time from my very helpful distributor to try a different unit just in case, but what can be wrong with a manual lens? Have any other users experienced difficulties in this area and if so can you make an recommendations to speed up this process, I would be grateful for any advice or suggestions.

Sincerely

DC Ireland.