What is the maximum length for SDI video cables?

There is no published maximum lengths for composite or other analog video cables because there are so many factors to take into account. If the driving source is a properly balanced output and the receiver has a properly terminated input and good quality, low loss co-ax cable is used, then the maximum distance can comfortably exceed 100 metres (300ft). However, many domestic video components do not have the best drivers and receivers and therefore, the maximum length will be reduced significantly. With analog signals (composite, S-video, component, RGB) the picture will start to become softer as the cable length increases. Eventually, the image will become unacceptable but it is up to the user to decide what is good enough. In all cases where a long video run is needed, use good quality 75 ohm co-ax cable and within a domestic environment, you should see very few problems.