I need a black and white camera. Since the cameras in the market, the ones available for astro-photography are quite costly, I am thinking of converting a digital camera to black and white. I see that the CCTV cameras are quite cheap and they tend to be black and white, but are they pure(no bayer filter attached) black and white cameras?
If you want to do "astro-photography" , spend your money on the telescope and tracking gear. The camera is almost incidental by comparison.
While a grayscale CCTV camera may be cheap, it'll also have crappy resolution and lousy signal/noise ratio. Even with the loss due to the color filter, almost any consumer digital camera will be better. it'll be better even if you just take color pix and flatten to greyscale in processing.
If you can collect RAW images and simply sum the RGBG pixels' signals by block, you'll get a nice boost in SNR per final pixel.