Rendering look

Vintage warm tones

Some old lenses tint everything warm, and there are two usual causes. Thoriated glass, used for its high refractive index, slowly develops a brown tint as the thorium decays, which cuts the light getting through and throws colors warm. Exposure to strong light can reverse some of that browning. Coatings play a part too. Some early coatings were designed for black-and-white film and noticeably warm color pictures, and the earliest silver Helios-44 is one documented case. To keep the warmth in your pictures, set a fixed daylight white balance, because auto white balance will correct much of it away.