Second hand video camera Nikon VH-3100 (8mm standard). Cost about 40€. I use it as secondary source of video signal.
It has much better lens than PCB camera and can provide colorfull pictures. Has ability to record movies. Much cheaper than colour CCTV camera with comparable lens.

The bad thing is that it needs more power and sensivity is much worst than PCB cam. Compare 4lux/F1.8 for camcorder to 0.05lux/F1.2 for PCB cam. It has built it microphone, but underwater it is useless. Camera is bigger (size and weight) than CCTV cameras.

One of the interesting features is LANC interface. See below for more details.

Parameters

8mm video standard gives 240 TVL.

• Video signal: PAL CCIR
• Cassette: 8mm
• Image device: CCD
• Lens: 37mm, F1.8, f=5.8-35mm
• Minimum illumination: 4lux (F1.8)
• Video output: 1 V_pp, 75ohm
• Power consumption: 5.6W (recording)
• Dimensions: 105x99x166mm (w/h/d)
• Weight: 580g
• Power: 6-9V

Example pictures

LANC interface

The lanc connector is used for controlling the tape transport of video equipment and the peripherals connected to it. This connector has the same function as the connectors indicated as CONTROL L or REMOTE.

This make it possible to control camera by microcontroller. Which means you can control zoom, focus from your control panel.

LANC links

• How SONY LANC™ protocol works description of commands (English/German).
• The Sony Control-L LANC Protocol description of the protocol.
• IRdeo LANC controler for PC computers (German, some pages in English).

Summary

My priority was to limit costs. This camera is rather old model (early '90). If you have possibility, try to buy Hi8 or SVHS camcorders (400 TVL). If you have external device to record video signal you can buy CCTV camera with good lens. It gives you better quality signal but costs minimum 100€ (420TVL 0.5lux/F1.2 zoom lens). But for the first try this camera is rather good choice, no wasted money when rov leaks.