What's the maximum resolution I can get using composite BNC input of a 800 lines monitor? video source: pd170 camera.

Some monitors have a comb filter which you can enable/disable... it will tradeoff resolution versus cross-color artifacts.

2- Resolution depends on how you measure it. There are many different methods.

3- What are you trying to do?

if the signal is good , there is no difference between DV an composite

can I get 600 lines from BNC connection?

Juan, what are you trying to do?

2- You could also take S-video coming off your camera.

Juan, resolution from a monitor is not just a counting of lines. Various elements go into what you 'see' as a 'clearer', more finally detailed picture. In general, if your signal is coming from a single analog bnc cable, (bypassing sdi signals for the moment), it will be a standard resolution picture. Period.

The reason why people are mentioning combing filters and S-VHS cables is because a single cable carries a "composite" video signal, the color & luminance information is carried in the same signal. Some colors, especially reds, will get fuzzy at the edges, saturated colors will introduce chroma crawl, etc. Combing filters and S cables, which seperate luminance and chrominance, help deal with issues like those, and the result is a picture with greater detail, even though the actual 'resolution' hasn't changed.

Other issues, such as the dot pitch of the monitor, the distance between the viewer and the screen, etc., also effect the perceived detail.

So after all that, your lone bnc cable is supplying a 640x480 or 720x480 (What is standard resolution these days anyway?) resolution, standard def.