Excuse me, about negative charge and positive charge

Negative correction refers to developing black and white negatives into positive films (slides). The effect depends on the film you use, such as Delta in Ilford and T-MAX in Kodak. The film using the new emulsion is better than Ilford HP5 and Kodak 3-X using the old emulsion.

The scientific name of "color-blind film" is "blue-sensitive film", which is only sensitive to ultraviolet and blue light. Let's not talk about other colors ~ but now there are fewer such films.

Panchromatic film is the film we often use in black and white photography. It is sensitive to all visible colors and ultraviolet rays.

It is not difficult to develop. Just buy your own developer and fixer and follow the instructions.

For other suggestions, please refer to Feng Jianguo's book Black and White Photography, which is a series of teaching materials for photography major of Beijing Film Academy. 25 yuan