The DSC-H70 appears not to offer a built-in black-and-white capture mode, and its in-camera editing also may not provide a B&W conversion option. The practical approach is to shoot in color and convert the photos to black and white afterward in editing software.

That’s often the better method anyway, because converting later gives you more control over contrast, brightness, and how different colors translate into grayscale. If your camera supports only JPEG, you can still get good results by editing the color file afterward. If RAW were available, that would give even more flexibility, but the key advice here is the same: capture in color, then make the black-and-white version in post-processing.