Choosing a lens for large depth of field and short focal length

This question is posted here because there is no stack exchange for cctv and cctv equipment that i found. While the problems I am encountering may not be specifically photography related, they quite obviously fall into a sub-category which is a direct descendant of classic or conventional photography where the methods of lens selection still apply. Voting for its removal is like telling a glider pilot with a wing geometry question that his question is invalid because it’s posted in a forum for motorized aircraft. The science is the same, the application is varied.

I designed my own night vision system using a dvd player screen + electronics, 11.1vdc lipo battery, two action camera mounting systems, a 2-7×32 rifle scope, pvc coupler (for eye relief spacing), a cctv camera, and lens, and a streamlight IR LED illuminator.

The lens is a pentax cosmicar c31631pl c1614er c mount 16mm cctv lens. The camera is a samsung scc-b2391 day and night digital camera.

Here’s my problem. The setup works, I can successfully get an image to display as planned, however I cannot get the image to clearly focus on both the reticule of the scope and the target. Also i have a bit of a fisheye effect happening. I suspect that a fixed focus and a mismatch in format (camera is 1/3 super-HAD-CCD lens is 2/3) respectively are to blame. Another issue that I think may be contributing is my inexperience setting up the auto iris, which has been a struggle for me as well. Its working all the time now without flickering or shutting completely with changing light. My previous setup was capable of achieving a sharp, focused image of both the crosshairs and the target. The problem again was that the image did not take up enough of the screen. The 16mm cctv lens gives a nice full screen image but not focused enough. How can i achieve focus on both the crosshairs and the target? I know that someone who knows how to setup photography equipment will be able to tell me what I need to do.

UPDATE: I have now switched to a Pelco F1.6/5-40mm C Mount Security Surveillance Video Camera Lens This has solved 90% of my problems. I am sure that I still have room for improvement, so any additional information would be appreciated. Also thanks to the people who actually provided helpful feedback to my previous question. Helping people who have questions or problems with technology they don’t fully understand is a literal life saver in the straight-vertical-learning-curve ocean of information that the internet provides, so thank you to those of you who took the time to look past the fact that the question may not be exactly on topic and answered. That is of course what has brought our paths together.